Studies and Researches on the Conformation of Spaces and Their Agglomerations

#### **Chapter 8**

## Impact of Urban Open Spaces on City Spatial Structure (In Case of Isfahan)

*Ghazal Farjami and Maryam Taefnia*

#### **Abstract**

Public spaces can be considered as important elements to improve the quality of the environment and increase the sense of citizenship. On the other hand, the cohesive network of urban spaces shows the integrated structure of a city's spatial organization, in which not only the connection of form and function is considered, but also meaning finds its place in a complex urban system. Since the spatial structure of the traditional Iranian cities is ingrained in geographical factors and culture of the settlements, the evolution of this structure in Isfahan as one of the most famous historical cities in Iran is examined. The aim of this study is to answer this question: How do urban open spaces impact city spatial structure? The research method is descriptive-analytical, which has been concluded in a process of content analysis. The development of Isfahan's structure over time and role of urban spaces in its formation has been studied. Entrances, key points, roads, and water edges as main urban spaces impact on city structure direction. The structure has changed from linear-nuclei to central-radial and finally, an integrated network to the Safavid era, but cohesive nature of the structure has changed from the Pahlavi period with multiple sections of streets.

**Keywords:** city structure, spatial structure, urban open spaces, urban context, Isfahan

#### **1. Introduction**

Looking at city structures, both open and closed parts are considered to form the shape of a city. Therefore, cities are not just about masses and not mere open lands but the combination of these two make the city structure, which differs in different regions based on so many factors.

The structure of traditional Iranian cities has a special physical-spatial cohesion and order that is guaranteed by their richness and physical quality. One of the most important features is the continuity of the city and neighborhoods through the centers, main passages, and the bazaar, which has led to the formation of a clear and legible structure in the city and the continuity of components and elements of the city. The composition and construction of the city in the past of Iran have been such that the main passages and the bazaar have been responsible for the connection between the important elements of the city.

However, since the first years of the present century, when the street has emerged as the dominant and decisive element in the city, urban cohesion has undergone serious changes. The street runs through the city, presenting itself as the powerful lips within the city, and from the integrated structure of traditional cities, only residential contexts remain, such as islands cut off from the arteries of urban life. At the same time, the spaces and elements of the communication network must establish an organized and regular relationship with the components and structures of the city and the current activities in it. Because the formation of urban spaces and elements along the roads is influenced by the behavioral patterns, culture of the people, and the economy of the society [1].

In contrast to the modern Iranian series, which are simply copies of the contemporary diffused European and American cities, the traditional Iranian city is concentrated and how much genius in its buildings combining diverse land uses in a tight relationship with each other. In this way, three main factors affecting the early compact Iranian cities may have been the physical environment of the Iranian plateau, trade and historical events, and the socio-political structure of the country [2].

One of the important but forgotten elements affecting traditional cities is urban open spaces formed among the compact masses of buildings. Therefore, this research is an attempt to investigate influential factors on city structures and identify the role of open spaces on spatial city organization. In traditional Iranian cities, the urban structure was based on the geographic characteristic of the surrounded environment. Since a vast area of this country is covered with desert and hot and arid climate, cities were shaped in a very compact and dense form. Besides the central courtyard of individual buildings, urban open spaces emerged as a joint element among the masses. On the basis of the carried out research, the paper analyses the historical development of Isfahan as one of the historical cities of Iran with a very compact context affected by geographical conditions, while urban open spaces still emerged as key elements in a very unique form.

#### **2. City structure**

The Latin root of the word structure "struere" means to build, grow, and evolve. Hence, the structure means "working together continuously to evolve." For example, living features grow and evolve in a continuous, purposeful, and highly organized movement. In this way, each structure has its own function and shape, which plays an important role in facilitating the function of the structure [3].

The structure is a complete set of relationships in which the elements may change but remain dependent on the whole and retain their meaning. The whole is independent of its relations with the elements. The relationships between the elements are more important than the elements themselves. Elements are interchangeable, but relationships are not [4].

Against the views of those who believe that structures are formed based on functions and goals, there is also the opinion that structure is determined by its elements and their combined features, regardless of the specific function and purpose [5]. The structure is a set of interdependent processes and interrelationships of elements or a network of relationships between elements' positions that are plotted within the external appearance of the object, the shape [6].

Some believe that the structure is made by the human mind and then projected onto the shape of the city. Researchers seek to discover the subconscious mind structures that are common to all societies. The latter group aims to find the relations and rules that have been effective in the formation of these structures to use them in the emergence of subsequent structures [7].

*Impact of Urban Open Spaces on City Spatial Structure (In Case of Isfahan) DOI: http://dx.doi.org/10.5772/intechopen.102553*

From all these definitions, it can be concluded that structure is a set of interdependent elements, in which the necessary and simultaneous mutual relations or partnerships between components take place abstractly and objectively and depending on the purpose, within a certain range.

The spatial structure of the city shows the order and the relationship between the physical elements and the uses in the city [8]. In other words, the spatial structure refers to a set of communications resulting from the urban form and the gathering of people, the transportation and flow of goods and information [9]. Alain Bertaud combines the spatial structure of a city into two components, namely the spatial distribution of population and the pattern of people's travel from where they live to the various destinations and places, where an important social activity or interaction takes place, such as the workplace, and knows the location of social gatherings [10].

Therefore, city structure includes various elements coming together creating a city with its own characteristic. These elements not only work individually but also generate unity resulting in a homogenous city structure. It does not matter if it is open or close space, but it is important to form in a way that integrates the whole structure. However, urban open spaces are dominant features reflecting the story of the city and residents' culture and lifestyle.

#### **3. Urban open spaces**

Open space, on the one hand, refers to a space that is relatively open, less closed, and has more limited space, and on the other hand, refers to a space opened by the masses to the majority of people. This refers not only to landscapes, such as parks and green spaces but also to streets, squares, alleys, and courtyards [11].

"If we want to clarify the concept of urban space without imposing aesthetic criteria, we have to consider the spaces between buildings in cities and other places as urban space," says Rob Carrier. This space is geometrically surrounded by various symbols. Only the clarity of its geometric features and esthetic qualities allows us to consciously consider the outdoor space as an urban space. Outdoor open space is defined for outdoor mobility and is divided into public, semi-public, and private [12].

Zucker considers urban space to be an organized, neat, and orderly structure physically for human activities and based on specific and clear rules; These rules are: the relationship between the shape and the body of the buildings enclosing the same shape and uniformity, with their diversity, the absolute dimensions of the bodies to the width and length of the space between them, and the angle of passages or streets to the square, and finally the location of historical monuments, fountains, and slabs or other three-dimensional elements that can be emphasized [13].

Bruno Zevi considers space to be the essence of architecture, and follows the same definition of urban space, stating that streets, squares, parks, playgrounds, and gardens are all empty spaces that are limited or defined as space [14].

Urban space in a general sense is a kind of interrelation between relationships and behaviors, while the place is adjacent to individual identities, in urban life, it is the most important factor of authentication and affects human behaviors. In addition, urban space, as a public area, is the place of emergence and revitalization of individual and social thoughts and desires, which is why it has a very important role in the development of societies.

Since the emergence of cities and the beginning of urban planning and urbanization is closely related to the need for interaction and the sociality of human beings, undoubtedly, these relationships need their own spaces. Cities are known as places of the emergence of human social relations throughout history, and even the type and quality of urban spaces have been quite effective in the manifestation of these

relations. Therefore, one of the most important elements of the urban context is the city structure formed and evolved based on human lifestyle in different periods [15].

The changes experienced in modern cities are reflected in the urban space, and this leads to the gradual extinction of public spaces in the urban structure. Increased urbanization and migration are leading to a loss of integration of public open space in city centers.

#### **4. Urban open spaces in iranian city structure**

The physical morphology of the traditional city of Iran is to a large extent a cultural-historical response to the natural environment, especially, the climatic conditions of the Iranian plateau. Its extreme climatic conditions are characterized by a shortage of water, high evaporation than precipitation, intense solar radiation, high seasonal temperature ranges, and damaging dust and sand storms [2].

The structure of traditional Iranian cities has a special physical-spatial cohesion and order that is guaranteed by their richness and physical quality. One of the most important features is the continuity of the city and neighborhoods through the centers, main passages, and the bazaar, which has led to the formation of a clear and legible structure in the city and the continuity of the components and elements of the city. The composition and construction of the city in the past of Iran have been such that the main passages and the bazaar have been responsible for the connection between the important elements of the city [16].

One of the important features of the old context of Iranian cities is its division into several neighborhoods because the historical city as a whole is composed of components in the form of a neighborhood [17]. In general, in Iran, the city was complex. Consisting of homogeneous and homogeneous neighborhoods that are integrated into a specific place based on relations, forms, and affiliations of ethnic, religious, professional, or territorial, and have kept their identity and originality in this way for years and until the new development. The city was considered as the main constituent units or as the cells of the city, the residence of a particular ethnicity, religion or group, and more than any other urban unit, within itself solidarity, unity, ethnic, family, and sometimes administrative, professional and class [18].

What has always been prominent in the construction and establishment of neighborhoods are the aspects of social, cultural, religious, or economic commonalities [17] and in the meantime, the separation of neighborhoods on the basis for differences in religious or ethnic beliefs and characteristics is more visible among large cities with larger and more diverse populations and in nomadic cities. For the emergence of each neighborhood, a limited and coherent geographical area, social interdependence between a specific group, and a specific city design were required for the spaces and houses of the neighborhood, the existence and permanence of the neighborhood depend on their existence [18].

The structure of ancient cities is known as the most obvious and complex part of the physical system that shows the social structures of the city along with its internal contradictions. Dynamics in the design of this structure causes logical relationships between urban components and systems and their function and process together.

One of the ways to organize the space in the historical cities of Iran was to connect the building mass continuously. This method can be seen at the micro level, such as neighborhoods, and at the macro level, as the whole city. For example, the bazaar, as the main and central street of the country, has been an important tool for the continuous growth of the city [19]. Next to, or along, some of the major bazaars in major cities were an urban or regional square. The bazaar was the most important road in the city and in most cases, it was connected to an urban square.

#### *Impact of Urban Open Spaces on City Spatial Structure (In Case of Isfahan) DOI: http://dx.doi.org/10.5772/intechopen.102553*

The main bazaar of cities are often linear and formed along the most important urban road. For this reason, in many historical cities of Iran, the most important part and the main element of the context is the main direction of its bazaar. A bazaar order was formed in its simplest form with shops located on either side of it. Many bazaars were gradually built and developed, and for this reason, the extension of the direction of these bazaars, following the natural shape of the passages, has been indirect and organic. Various guilds were stationed along the main bazaar line, thus placing various activity groups in different parts of the mainline. In some large cities, two or more main directions appeared in parallel or intersecting.

One of the main features of past spaces is their centrality and confinement. Each spatial area is central to its surroundings. Gradually, the construction method of the central building replaced the central space. The part of the building that could not be designed due to the connection with the adjacent building was exposed from all sides by being located in the middle of the space, and the necessity of designing all aspects of the building was raised. Each building peaked independently of adjacent buildings in height so that the horizontal connection gave way to the vertical connection [20].

One of the historical cities of Iran is Isfahan, located in the hot and arid area close to the desert while a river is passing through the city. Isfahan has a very special city structure based on various environmental issues. However, urban open spaces play an essential role in city structure.

#### **5. Spatial structure of Isfahan based on urban open spaces**

Isfahan is located in 32°38′30″ N latitude and 51°38′40″ E longitude, about 340 km south of Tehran and the capital of Isfahan Province (**Figure 1**) [22]. The main factors of the prosperity of Isfahan during the time have been the Zayandehrud River and the location of the city in the center of the Iranian plateau. So, throughout its history, it has been either the capital or one of the most important parts of Iran [23].

**Figure 1.** *Location of Isfahan in Iran [21].*

The spatial-physical structure of each city is closely related to its history. Therefore, a review of historical periods can enlighten how the city is organized during the time. Most of the old cities of Iran had a specific structure of the main urban elements and functions such as palaces, bazaars, squares, mosques (After Islam), schools, etc. The physical characteristics of the evolution and development of the main structure of Iranian cities up to the contemporary era were mainly in harmony with the growth of the city [24].

The city of Isfahan has been continuously evolving for more than 2000 years. Until the early Islamic centuries (750–1258), Isfahan consisted of two districts, Jay and Judea (**Figure 2**). During the Sassanid Empire, Jay was the administrative and governmental center and included urban elements, such as squares and bazaars. In contrast, Judea and the rural agricultural areas in the north and south of the Zayandehrud River were inhabited [26].

**Figure 2.** *Isfahan in the late Sasanian and early Islamic periods (Abbasid era) [25].*

After the Arab invasion of Isfahan, in the Abbasid era, Jay gradually became a ruin, while Judea survived. The physical form of the city in the pre-Islamic era included three distinct parts: the governmental area, the central city, and the outer city, but in the Islamic time, the past structures underwent changes, the most important of which was the Grand Mosque (Jame Mosque), as a characteristic of the urban element [27]. Rural groups connected with lines of communication and formed an urban body (**Figure 2**) [28]. The structure of Isfahan in the Seljuk era (1037–1194) was a combination of linear and centralized patterns. Due to the comprehensive development of the city, the central position of the structure was located around the Old Square as the main center of access. The linear part of the city structure has continued in the form of a bazaar to the gates, which has provided the possibility of development in the future [29]. Therefore, the most important urban spaces in this period have been squares, bazaars, and transportation routes which are created the structure of the city (**Figure 3**) [31].

**Figure 3.** *Structure of Seljuqid Isfahan. Modified by authors [30].*

After the selection of Isfahan as the capital of Iran in the Safavid Empire (1501– 1722), the main structure of the city was formed. During this period, Chaharbagh Street, Naghsh-e Jahan Square, and its connection to the Old Square by the bazaar was one of the most important measures in urban spaces. Naghsh-e Jahan Government-Ceremonial Square caused the future development of the city to be drawn to this direction and then to Hezarjarib gardens on the other side of the river (**Figure 4**) [33].

During the Qajar period (1789–1925), the empty space of the Old Square began to fill and lost its importance as a reference point in the structure of the city [34].

Over the Pahlavi period, modernism and its developments by ignoring the context, history, and structure of the city, introduced a kind of intervention in historical areas that led to spatial isolation and destruction of traditional structures in the city.

**Figure 4.** *Structure of Isfahan in Safavi era [32].*

During this time, the structure of the city was physically changed from a linear-nuclei model to a network structure, so that the old structure gradually faded in the minds of the people and lost its physical-structural value and reputation (**Figure 5**) [25].

**Figure 5.** *Structure of Isfahan in Pahlavi period [25].*

The first planning measures in this period were street plans in the old contexts and their continuation to the outside based on the grid-system pattern and separation of urban functions, which led to the fragmentation of the old context of Isfahan [35]. This kind of intervention has led to the apparent separation of the main old parts of the city and the destruction of its traditional structure, which led to the complete decline of historical centers in the 20th century. Therefore, it was necessary to prepare master plans. Modern major urban planning began in Iran in the 1950s and 1960s when the first master plans were prepared for some important cities like Isfahan [36]. Isfahan has three main master plans in 1960, 1971, and 1988 (**Figures 6**–**8**). Then, detailed plans were prepared based on the regions of the city,

**Figure 6.** *First master plan of Isfahan [35].*

*Impact of Urban Open Spaces on City Spatial Structure (In Case of Isfahan) DOI: http://dx.doi.org/10.5772/intechopen.102553*

**Figure 7.** *Second master plan of Isfahan [35].*

**Figure 8.** *Third master plan of Isfahan [35].*

but with the non-implementation of more than 70% of the comprehensive plans, the strategic development plans were replaced. City Development Strategy (CDS) is a comprehensive flexible planning framework designed to empower urban communities to control and manage the consequences of rapid economic change and increase the growth of economic and social inequalities [37].

### **6. How urban spaces of Isfahan impact city structure?**

The first question that should be answered is: what is the city structure? The structure of the city is a set consisting of the main axis and an interconnected network of land uses and urban elements that integrates the whole city and extends hierarchically in all parts of the city on a proportionate scale (**Figure 9**). This complex is the foundation of the spatial-physical organization of the city and indicates the general and common characteristics of the city [25].

**Figure 9.** *City structure: Main axis and an interconnected network of land uses and urban elements [25].*

In other words, this complex as a linking structure includes parts of the city that are in public use, including movement structure (main roads, public transport cores, and main walking routes), interaction places, gathering places, and public buildings. City context with its specific physical and social characteristics is formed and organized by the city structure. This structure breaks the experience of the city into pieces with spatial locations and at different scales that make the city legible and conceivable. It changes over time and the elements that remain unchanged create the cultural landscape of the city. This structure can also be linked to the natural landscape (**Figures 10** and **11**) [38].

The second question is what is the urban open space? Urban space is the scene where the story of social life begins. It is a space that allows all people to access and work in it. Based on researches, there are different points of view about urban open space typologies (refer to [39]) but the focus of this study is based on five main categories: entrances urban nodes especially squares, paths, water edges, and urban stairs. The entrance is a joint for connecting two places. The entrances of the cities and the

**Figure 10.** *City structure elements (authors).*

*Impact of Urban Open Spaces on City Spatial Structure (In Case of Isfahan) DOI: http://dx.doi.org/10.5772/intechopen.102553*

#### **Figure 11.** *City structure: Movement structure, interaction and gathering places, and public buildings [25].*

neighborhoods entrances are public spaces that play the role of urban space. Squares are the most influential urban spaces in the mental image of citizens. They can be on an urban, local scale, or play as a ceremonial place. In people's minds, paths are not only the lines that enable the connection of different parts of the city, but also the spaces that accommodate the most social life. They have the largest share of other urban spaces and are manifested in the form of urban streets, passing streets, local streets, boulevards, alleys, dead ends, and pedestrian ways. Water in the city can play a key role. The water's edges can be the basis of different social happenings. The last one is urban stairs which can be a place of social events in addition to the physical role of access (**Figure 12**) [40].

**Figure 12.** *Urban space typology.*

According to the above issues, the last question is what is the role of urban open spaces on the structure of Isfahan? The following diagrams show the evolution of changes in the city structure over time and the interaction of these two main factors.

As mentioned, Isfahan initially consisted of two main cores and the dominant activity model of the people of the city was gardening. These gardens were mainly located on the banks of the Zayanderud River, and people had learned to use the River to irrigate their gardens, thus "Madi's were formed. This pattern of residential activity may be the answer to the question of why the early settlements of Isfahan were formed at a distance from the Zayanderud River. Supplying water through wells was much easier than supplying water to gardens, in addition to the fact that the river was not permanent. People created branches (Madi) from the Zayanderud to deliver water to the gardens in a controlled manner [41].

In the Sassanid period, Zayanderud, Madies, two main cores (Jay and Yahudiyyah), and scattered points of residences created the basis of Isfahan's structure in the multiple nuclei model. The river and Madies, as the first urban open spaces, played a significant role in locating the centers. In addition, the settlements around Yahudiyyah were organized by the Madies in a linear-nuclei connection (**Figure 13**).

In early Islam, the Isfahan spatial organization remained in linear-nuclei type, but the residential areas around Yahudiyyah joined together and organically formed in central organizing. This area is the foundation of the development of settlement as a city in the next years. The oldest neighborhood of Isfahan is in this part of the city and at the same time, functions such as bazaar and mosque were formed next to the palace. Zayanderud and Madies played their role as previous years in the structure of the city (**Figure 14**).

**Figure 13.**

*Isfahan structure in late Sassanid. The structure is linear-nuclei. Edited by authors [42].*

#### *Impact of Urban Open Spaces on City Spatial Structure (In Case of Isfahan) DOI: http://dx.doi.org/10.5772/intechopen.102553*

During the Seljuk period, the foundations of the Iranian-Islamic city emerged and the first square of the city was formed at the linkage of Joybareh, Dardasht, and Karan neighborhoods and next to the bazaar. The square and the bazaar, as the main urban spaces, formed the core structure of the Seljuk city along with the paths leading to the city gates. The city gates, as key points of crossing the city wall, strengthen the structure. In this period, the structure of the city core is centralradial with a predominant orientation northeast-southwest and on a larger scale with the Madies and the river is as a linear-nuclei (**Figure 15**).

**Figure 15.**

*Isfahan structure in Seljuk era. The structure is central-radial in central of city and linear-nuclei on a larger scale. Modified by authors [26].*

During the Safavid period, with a rapid increase in population, four gardens in the middle of the city became residential areas, and the government decided to create new gardens instead of ones that had changed their use, and so the gardens appeared around Chaharbagh Street [41]. Thus, the structure of the city was drawn to the south under the influence of the street route. New Square (Naghsh-e Jahan) was built in linkage to the bazaar between Faden and FarshadiMadies, and following the connection of Khajoo Bridge to Naghsh-e Jahan Square, another part of the city structure was directed to the southeast (**Figure 16**). The crossing of Chaharbagh over the river towards HezarJerib gardens and the axis of Khajoo towards the Takht-e-Foolad Cemetery brought the river to the heart of the city structure. These intersections designed the structure of the city as an interconnected network (**Figure 17**).

It is worth noting that before the Safavid era the growth of the city was organically based on Madies and the river but at this time, the city was developed according to the designed plan (**Figure 18**).

During the Pahlavi era with the aim of renovating the worn-out contexts left from the Qajar period, street construction continued based on the previous structure (**Figure 19**).

**Figure 16.** *Naghsh-e Jahan Square [43].*

**Figure 17.** *Unban open space along the Zayandehrudriver [44].*

*Impact of Urban Open Spaces on City Spatial Structure (In Case of Isfahan) DOI: http://dx.doi.org/10.5772/intechopen.102553*

#### **Figure 18.**

*Isfahan's structure in Safavid era. The structure is an integrated network. Modified by authors [26].*

#### **Figure 19.** *Isfahan's structure in Pahlavi era (1956) [45]. The structure is networked.*

During this time, the new structure expanded its network by passing through the old texture, regardless of the size and orientation of the context pattern. From this period onwards, the streets are the main public open spaces that shape the structure of the city (**Figure 20**).

#### **Figure 20.**

*Isfahan structure in 1970's and 1986 [46]. The structure is networked.*

**Figure 21.** *Old Square [47].*

With the regeneration of the Old Square in the contemporary era, it returned to the structure of Isfahan and along with the bazaar and Naghsh-e Jahan Square, physically organized the historical core of Isfahan (**Figure 21**).


So as a result, the evolution of the structure of Isfahan over time is as follows (**Table 1**):

**Table 1.**

*Development of Isfahan structure and the main urban spaces affected over time.*

### **7. Conclusion**

Today, the viewpoint of natural and indigenous conservation refers to the fact that by maintaining and strengthening the indigenous structure, the social capacities of the place can be formed [48]. Urban open spaces are the main components and the most basic elements in the physical structure of a city. By identifying them, as well as determining their role in space and connecting their functions, we can take action to revitalize the ossification of traditional cities. This strategy is reinforced by defining a multifaceted role for them and a new skeleton is expected to be formed in the city. With such an approach to changing the structure of the city and strengthening the urban joints that connect the past and history to the present and the future and diverse activities to each other and citizens to civic life, the quality of urban places and spaces is improved and sense of richness and belonging strengthen.

Urban open spaces as vital factors play an important role in connecting the constituent elements of the city. The old context of cities, due to the preservation of their original structure, has appropriate models for recognizing and analyzing life-giving open spaces. These open spaces generate hierarchical space organization; breathing spaces among solid parts and city livability. Regarding the modernization process of cities, these valuable spaces were faded while mass spaces are mostly considered. It has resulted in very massive urban contexts affecting social interaction, legibility, city image, etc. Isfahan as one of the historical cities of Iran is well-known because of its urban open spaces which create specific city structure.

As mentioned, entrances, key points (nodes), roads, and water edges are the main urban spaces that in each period in the form of city gates, squares, and Madies routes and the river have strengthened the structure of the city. During the Safavid period, these elements in an integrated connection cause the expansion of the city to the south. With the passage of Chaharbagh through the Zayanderud River, the river finds a central role in the structure of the city, and these two artificial and natural axes form the foundation of the city's later expansions. During the Qajar period and after that, the Old Square and the Madies lost their role in the structure of the city. With the construction of several streets during the Qajar, Pahlavi, and contemporary eras, the structure of the city expands in the form of a network and the roads are the main elements of the city.

Today, with the revitalization of the valuable historical structure of the city, such as regeneration of the Old Square and also rehabilitation of Madies green network, their role in the structure of the city has regained its importance.

#### **Author details**

Ghazal Farjami1 \* and Maryam Taefnia<sup>2</sup>

1 Department of Architecture, Daneshpajoohan Pishro Higher Education Institute, Isfahan, Iran

2 Department of Urban Development, Daneshpajoohan Pishro Higher Education Institute, Isfahan, Iran

\*Address all correspondence to: qazalfarjami@gmail.com

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Impact of Urban Open Spaces on City Spatial Structure (In Case of Isfahan) DOI: http://dx.doi.org/10.5772/intechopen.102553*

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[29] Sadeghi S, Ghalehnoee M, Mokhtarzade S. The analysis of the effects of contemporary urban development plans on the spatial structure of the north of Isfahan's historical core. Quarterly Journal of Urban Studies. 2012;**2**(5):3-12

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*Impact of Urban Open Spaces on City Spatial Structure (In Case of Isfahan) DOI: http://dx.doi.org/10.5772/intechopen.102553*

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#### **Chapter 9**

## Dialectics of Mainstreaming Agriculture in Urban Planning and Management of Cities of the Global South

*Nkeiru Hope Ezeadichie, Vincent Aghaegbunam Onodugo and Chioma Agatha John-Nsa*

#### **Abstract**

Most cities in the global south have evolved overtime with significant organic changes in their wake. One of the noticeable changes is the emergence of pockets of city-based agricultural activities, a previously rural-based activity. There are varying interpretations behind this new trend. With increased agglomeration arising from rural-urban migration, residents resort to farming as a panacea to urban challenges. Even employed urban residents resort to agriculture for supplementary income. This emerging scenario has generated debates, dialectics, and polemics among stakeholders as to the propriety or otherwise of this development. This chapter, therefore, takes a panoramic view to all the sides of the issue through review scoping of desktop research method. Specifically, it examines the scope of increase in urban agriculture (UA), the types and nature of UA; urban planners' attitude towards UA, and then propose the management strategies such as promoting agriculture-friendly urban plans for access to agricultural land and practices. The findings revealed that UA takes place on residential land, undeveloped private/ public lands, and riverbanks. The prominent UA activities are animal husbandry, aquaculture, cultivation of food and cash crops, etc. The urban-planning measures for integrating UA into the urban environment include inculcating UA-responsive policies in broad plans.

**Keywords:** urban agriculture, agglomeration, urban planning, urban management, global south

#### **1. Introduction**

The increased urbanization of the world cities has thrown up varying opportunities and challenges in its wake. A combination of factors such as population increase, a rapid climate change situation and higher incidences of extreme weather conditions, energy limitations, water scarcities and food security concerns, have bequeathed some air of uncertainty on the evolution of global cities ([1] *c.f* [2]). Due to the current unparalleled city growth, urban areas now offer living space for more than half of the world population that needs to be fed [3] and it is projected that by 2050, 70% of the world population will reside in cities ([4] *c.f* [2]).

Adedeji and Ademiluyi [5] suggest that population increase adversely impacts food security from both ends. It increases food demand on the front end and also indirectly decreases its supply through environmental deterioration, construction of buildings and marginalization of food production at the back end. The implication is that of the marked increase of agricultural activities in areas hitherto that was not known for such. Available statistics show that the need to feed a rapidly growing urban population has driven above 800 million people on a global scale to practice urban agriculture (UA) [6]. UA is a pervasive phenomenon that is found in both advanced and developing countries ([7] and Mlozi [8] *c.f* [5]). Further challenges associated with food security in an urban setting are the continuous increase in rural–urban migration, environmental implications of large-acre commercial agriculture and overall access to safe and nutritious food [2].

Urban and peri-UA is the 'growing, processing and supply of food' and related products through the cultivation of plants and occasionally raising of livestock in and about cities to feed the local populace ([9] *c.f* [6]). UA comprises small to large areas in and about cities, like community gardens, vacant plots, balconies, farms or gardens on the rooftop, indoor farms and greenhouses [6]. In developing countries, UA is a progressively vital livelihood activity, which adds considerably to both family livelihood arrangements and the urban informal economy [10]. Studies of urban and sub-urban agricultural systems in West Africa are few [5]. However, Game and Primus [6] noted that more than 20 million people in West Africa engage in UA. A broad range of production ventures is found in the agricultural sphere spanning family subsistence to extensive commercial farming. Korir, Rotich and Mining, [10] suggest that the supply and distribution cost from rural foods or the cost to import food for the urban area has been on the increase and it was estimated that urban food insecurity would rise if nothing is done to reverse the trend. Thus, in some parts of Lagos city, unauthorized farms are mostly found along wetland areas used for the cultivation of perishable goods particularly vegetables (carrot, lettuce, spinach, cabbage, etc. while in parts of Ikoyi and Lekki, home-plots are used by the people to cultivate vegetables, do poultry farming for chickens, ducks and turkeys) [5]. Urban farming in most developing nations is embarked on by two groups, recent migrants and traditional farmers, who have been immersed in urban development [10]. The practice of UA in different countries revolves about four broadly distinct farming systems: animal husbandry, aquaculture, agro-forestry and horticulture [10]. Meanwhile, the various parts of the city where agriculture is practiced have been researched by scholars. UA commonly occurs around or in-home spaces, a large expanse of undeveloped private or public land [11], private residential land, roadside borders, river banks and other public lands [10].

UA is harnessing the gap left by rural agriculture (RA) which is the primary producer of urban food as it failed to attain urban food security [6]. UA complements RA in relation to self-provision, marketing and supply flow of food [6]. Furthermore, there is a rising fear that rural agriculture will constrain access to land for accommodation purposes in the rural areas (through land grabbing) and provoke migration to cities thus decreasing rural populations ([12] *c.f* [6]). Nevertheless, UA is doubtful to make any urban area or most of its households entirely self-sufficient in their food requirement ([13] *c.f* [6]).

Presently, the absolute and relative increase in food insecurity and urban poverty is becoming a challenge due to the rising urbanization facing many parts of the world. However, UA is gaining prominence as a mitigating approach to challenges of many cities of the world [10]. Urban farms are mostly on former vacant or underused spaces in the city and are then converted into attractive, safe and useable areas [14]. According to United Nations Development Programme (UNDP) ([15] *c.f* [16]), the international policy area of UA, which addresses poverty, was emphasized at the HABITAT agenda

#### *Dialectics of Mainstreaming Agriculture in Urban Planning and Management of Cities… DOI: http://dx.doi.org/10.5772/intechopen.104269*

1996 in Istanbul. In the same vein, the UNDP published an influential volume on UA, which highlights the activity's importance for the creation of a job, eeding urban dwellers and creation of an environmentally sustainable urbanization. United Nations Habitat affirmed that UA in many cities plays a significant role in sustaining environmental integrity and adding meaningfully to the achievement of self-reliance in relation to food. This is achieved through the enhancement of livelihoods of the urban poor, and by growing of varied range of crops and breeding of livestock with considerable yields [10]. The physical environment where people play, work and live, has significant impacts on their health. Areas with clean and safe outdoor spaces for recreation, meetings and exercises, impact positively on the health of the dwellers [14]. Hagey, Rice and Flournoy [14] show that the gains accruable to communities due to the presence of urban farms include: offering beautiful, safe, and welcoming areas for neighbors to come together and play; increasing a sense of communal living and making safer environs.

Korir, Rotich and Mining, [10] revealed that urban households can enhance both food consumption (better access to a low-cost source of protein) and food quality (as poor households in cities who participate in farming consume more fresh vegetables than other households in similar class). Households who take part in community gardening are capable of offsetting usually 30%-40% of their yield needs by consuming food cultivated in their own gardens (Seattle Department of Neighborhoods in Hagey, Rice and Flournoy, [17]). The import of UA to nutrition and food security is likely its most vital advantage [10]. UA is promoted as it is widely seen as contributing to food security, the dispensation of providing creative income opportunities and as an approach mainly geared towards supporting the poorest of the poor in the urban population [16]. Korir, Rotich and Mining, [10] revealed that many claims have shown that the principal motive people engage in UA in cities is in reaction to unreliable, insufficient and irregular access to food supplies and the absence of purchasing capacity. Urban farming offers many gains to struggling societies: neighborhood revitalization, better access to healthy food, workers' training and occupational development [14].

The foregoing has riveted the attention of scholars towards assessing the broad implications of UA. This chapter joins the growing number of works to consider the many sides of the debates on this subject. The authors adopted a more explorative than prescriptive approach to the discourse. The desktop research method through scoping review proposed by Arksey and O'Malle [18] as cited in De Beer et al. [19], was employed in the exploration; and online resources were extensively utilized in the discourse.

#### **2. Methodology**

The study employed the desktop research method. For a comprehensive study, a scoping review of the literature was applied to explore the nature and dynamics of UA and the planning panaceas for mainstreaming the same into the urban environment. The methodological structure employed was modified by Levac, Colquhoun and O'Brien [20] as cited in De Beer, Gaskin, Robbertse and Bardien, [19], from its initial exposure by Arksey and O'Malle [18] as cited in De Beer et al. [19]. The scoping appraisal for this chapter trailed the first five phases of this methodological structure.

#### **2.1 First step: defining the objectives of the review**

The review objectives include to:

1.Examine through available literature the scope of increase in UA in the world


#### **2.2 Second step: identifying appropriate search strategy for the study**

Studies relevant to the study were identified by examining electronic catalogs through the use of various search engines, especially google.com. This opened up electronic databases such as MEDLINE, Schimago, EBSCOhost Web of Science, Scopus, Google Scholar, etc. related to the study objectives. The search word or terms include: UA or farming in cities, urban planning and UA, types of UA, etc.

#### *2.2.1 Eligibility criteria*

Articles published from 1995 to 2020, were sought. This was to cover the duration of time perceived to be when UA began to gain scholarly attention. Another reason for choosing from 1995 to 2020, was to avoid selecting materials that are obsolete and do not reflect the present technological and societal changes already in place and further evolving. All pertinent peer-reviewed educational materials and those written in the English language were selected.

#### **2.3 Third step: selection of material for the study**

The screening of the title was done by the three researchers using the eligibility criteria. Where it seemed that articles were suitable for the theme, one of the researchers screened the abstracts in relation to the inclusion criteria. The articles were retained if they met the inclusion or exclusion criteria, that is, they answered the research question(s) or tendered towards meeting the objective of the study.

#### **2.4 Fourth step: extracting and charting the data**

This study followed Arksey and O'Malley's [18] suggestions concerning a standard data extraction procedure. The procedure employed for this review comprised details of author, study location, methodology, publication year, language and communication requirements and other relevant discoveries.

#### **2.5 Fifth step: collating, summarizing and reporting results**

The relevant articles were collated and relevant information on the study objectives was retrieved and reported. A total of 12 articles were considered relevant and retrieved, from which 16 other scholarly information was retrieved. This makes a total of 28 referenced materials for this review study. Those utilized in this study, were articles related to African countries like Nigeria, Kenya, Zimbabwe and a little of other articles centred in developed countries like America.

#### **3. Results and further discussions**

With the growing interest in sustainability as an essential concept in urban planning, localized systems of food production ought to be encouraged and

#### *Dialectics of Mainstreaming Agriculture in Urban Planning and Management of Cities… DOI: http://dx.doi.org/10.5772/intechopen.104269*

assisted [21]. Regardless of the divergent opinions about the import of UA, it continues to rise worldwide ([22] *c.f* [2]) and is positively impacting the course of survival and poverty alleviation ([23] *c.f* [2]) of over 800 million persons with 200 million out of them being urban farmers [2]. The World Commission on Environment and Development (WCED [24]: 254 *c.f* [16]) report advised all governments in the developing world to "*consider supporting urban agriculture*".

In contrast to the valued importance of UA, its negative impacts are also projected such as its situation in close proximity to populated regions and livestock farming contributing 30% of greenhouse gas emissions [6]. Moreover, Korir, Rotich and Mining, [10] opine that UA must, thus, be viewed as a permanent and dynamic aspect of the urban ecological and socioeconomic system, utilizing normal city resources, contending for water and land with other urban activities, affected by urban plans and policies, and supporting urban economic and social advancement. Furthermore, Rogerson, [16] shows that UA is not a safety net for 'the poorest of the urban poor' since the proportion of families in the ultra-poor partaking in agriculture was significantly lesser than higher-income groups.

There is presently a universal recognition of the significance of UA in most nations of the world and particular in the African continent. Existing literature reveals that over the past ten (10) years, fast growth in concern and activity in UA has risen greatly ([25] *c.f* [10]). The renewed interest in UA in the late 1980s and early 1990s demonstrates its importance for creating more sustainable rapid urbanization globally [2]. A study in Kenya indicates that about 64% of households in the city engage in some form of UA ([26] *c.f* [10]). An appraisal done in Cape Town of an urban food gardens initiative showed that UA provides gardeners prospect to get involved in a development scheme that holds great potential and can grow into a commercial venture if enough attention is paid to agricultural development, policy issues, land restructuring and livelihood creation [16]. It is expected that 200 million city dwellers provide 15%-20% of the world's food [10]. Broadly speaking, there is a propensity towards more system of intensive production that better meets the rising urban food demand [5].

UA still gets the least importance in several countries, especially in the aspect of development planning. A critical step in the development of UA is the integration of the same into the urban land use structure and the formation of an enabling policy environment [10]. Decision-makers and urban planners are confronted with the problems of acknowledging the significance of UA production to city sustainability and adjoining areas and several planners believe that urban planning and agriculture are relatively unrelated [5]. For this reason, UA is frequently informal and tends to be segregated to the cities' peripheral, far away from infrastructure and markets without evaluating the environmental, economic and links with other facets of the city [5]. In Kenya, policies on UA have not been considered in the past by the government as a worthwhile livelihood alternative. In Nairobi, regardless of the high level of practice, UA is not an accepted urban land use and it is not classified in land use zoning [27].

In the present situation, introducing UA would be a feasible means of attaining sustainability that tackles structural variations engendered by globalization to groups, their food systems and the value of life for urban dwellers. That is the reason for the attempt to reimage 'the city as a farm' by some urban designers. The American Planning Association also recognizes the significance of integrating UA into the planning of various land-uses in cities ([28] *c.f* [2]). The neglect of UA, in city planning, has created several problems in most cities of developing countries. Some of these problems include physical chaos and its associated challenges of unsustainable city growth and environmental insufficiencies which are a clear demonstration of inadequate and inappropriate land use planning that acknowledges and integrates certain facets of the city into the process of land-use allocation, and mark-out specific tools of administering them. It consequently necessitates that contemporary urban planning approaches should recognize the current urban realities and needs and accept urban livelihood approaches such as urban farming as part of the basis for urban planning and management [5].

Interest in urban and sub-urban agricultural production is largely low amid policy, hence, a consistent approach to UA is hardly available ([29] *c.f* [5]). Thus, the management strategies to UA demand the following points as observed from literature:


There is a pressing need to appraise zoning decisions and land-use planning and embracing more flexible guidelines to assist the urban poor advance UA instead of eliminating it [5]. Furthermore, urban planners should make effort to uphold multifunctional land use, and bigger public participation in the administration of urban open spaces as a means, incorporating UA as a vital model in programs of urban development. And likewise enable negotiation between diverse stakeholders for consensus building on UA [5]. Thus, UA must be incorporated into the urban master plan and a comprehensive modification of the urban regulation needs to be undertaken to add UA as a formal part of urban land use. The "New Urbanism" paradigm aims at correcting the trend of "Urban Sprawl" by utilizing insight gained from traditional urban development methods and thus preserving green areas for active recreation, natural habitat and useful agriculture [5].

#### **4. Conclusion**

This chapter discusses the growing phenomenon of UA, which emergence is more out of necessity than careful systematic planning. The growing urbanizing of global cities generally and especially global south cities in particular, largely due to migration and population increase has exacerbated food insufficiency and security. Consequently, UA evolved to fill the gap created by the food demand and

#### *Dialectics of Mainstreaming Agriculture in Urban Planning and Management of Cities… DOI: http://dx.doi.org/10.5772/intechopen.104269*

supply conundrum from the rural setting. The findings revealed that UA takes place around or in-home spaces, a large expanse of undeveloped private or public land, residential land, roadside borders, river banks and other public lands. The prominent UA activities are animal husbandry, aquaculture, agro-forestry, horticulture, cultivation of perishable crops carrot, lettuce, spinach, cabbage, etc. Traditional urban planning as usual is foot-dragging to acknowledge the organic emergence of UA and integrate it into its planning. Instead, it prefers to view it as an abuse of urban space and dwells more on the nuisance it poses to the environment and constraints it gives to land availability for residential and other formal purposes [30]. This chapter posits that there should be a holistic examination of the pro and cons of UA. It submits that, since, UA has come to stay, it offers employment and food lifeline to a teeming population of urban residents, and it may be mainstreamed in urban planning to maximize the benefit while minimizing the negative side effects. Some of the suggested measures that can enhance the achievement include promoting agriculture-friendly urban plans for access to agricultural land, irrigations, manure and transportation network for distribution of produce, offering safe and accessible land, changing some open spaces and vacant lands to agricultural use, inculcate UA-responsive policies in broad plans.

### **Author details**

Nkeiru Hope Ezeadichie\*, Vincent Aghaegbunam Onodugo and Chioma Agatha John-Nsa University of Nigeria, Enugu, Nigeria

\*Address all correspondence to: nkeiru.ezeadichie@unn.edu.ng

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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#### **Chapter 10**

## Reusable Cities: A Circular Design Approach to Urban Regeneration through Materials Reuse

*Serena Baiani and Paola Altamura*

#### **Abstract**

The "circular city" reduces its environmental impacts from many points of view: from construction-related CO2 emissions to energy production. The key areas for the implementation of an "urban policy for transition" are mainly oriented toward the reuse and recycling of materials from the building processes and urban value chains (urban mining), also through reuse practices of the existing building stock. The results of the research activities, reported in the present contribution, demonstrate the possibility of integrating studies on the environmental benefits of recycling in the building sector, with investigations on the potential of reuse to increase the overall eco-effectiveness of building interventions, interpreting the urban built environment in the perspective of a "reusable city." The hypothesis for a real reduction of raw material consumption in the construction sector is to combine the use of secondary materials with the reuse of building components, resulting from partial or total deconstruction and of materials from other waste streams, not belonging to the construction sector. Therefore, the research sought to understand to what extent the reuse of architectural components and waste materials from other industries can contribute to increasing resource efficiency at the local scale, reducing the consumption of materials, land, and energy.

**Keywords:** circular cities, urban mining, reuse, building materials, Harvest Map

### **1. Introduction**

#### **1.1 Circularity and climate neutrality: the role of cities**

"Rapid urbanization and increased consumption have led to economic growth in many parts of the world, but have also created unprecedented amounts of waste" [1]. The linear economy paradigm, the so called "buy-use-dispose" model, as adopted globally in particular in cities, is no longer sustainable, especially because of the growing production of waste, which is becoming unmanageable in many contexts. The UN Agenda 2030 [2], in fact, within Goal 12 of the Sustainable Development Goals, "Ensuring sustainable consumption and growth patterns," calls for significant waste prevention, reduction, recycling, and reuse by 2030. As the demand for natural resources is constantly increasing along with waste production, circular economy and material resource efficiency represent the only approaches that can help to face the challenge of decoupling growth from resource

consumption, tackling the "dual issue of increasing waste and decreasing resources by incentivizing actors throughout the value chain to extract maximum use from both existing products and the elements within them" [1].

Implementing the circular approach means reconfiguring all material flows within the city (building materials, water, solid waste, electronic waste, and even heat and energy), in order to avoid waste. Urban areas, in this perspective, represent an ideal environment to implement circular economy, starting from the resources embodied in the built environment and in particular in the existing building stock. Cities around the world are already moving in this direction, experimenting actions and interventions to promote interactions among different value chains and stakeholders, which can effectively foster circularity, urban mining, and sharing economy. This the case for Montevideo, for instance, where less than 2% of the solid urban waste goes to landfill via the waste collection system and, thanks to the support of ARUP, circular economy is being implemented as a strategic approach to enhance the city's resilience [3].

Indeed, cities play a central role in the transition toward sustainability and circular economy: urban agglomerations contribute significantly to climate change and the overexploitation of resources, with impacts including land use, soil consumption, pollutants due to mobility, water and energy consumption, air quality, waste. Nevertheless, with their high concentration of resources, people, capital, data, cities offer excellent chances for cross-collaboration between all key actors (individuals, companies, government, civil society, research, etc.) that to take action and "lead to a more sustainable and livable future for the next generation of urban dwellers" [1].

In fact, as stated in 2020 by the European Commission in the updated Circular Economy Action Plan [4], circularity is a prerequisite for climate neutrality, having an important impact on climate change mitigation and adaptation and on greenhouse gas emission reduction, through carbon removal. Actions can be naturebased, including through restoration of ecosystems, forest protection, afforestation, sustainable forest management, and carbon farming sequestration, or based on increased circularity, for instance, through long-term storage in wood construction, reuse, and storage of carbon in products such as mineralization in building materials.

#### **1.2 A vision of a circular city**

Transitioning to circular cities entails defining a vision. According to the Ellen MacArthur Foundation [5], a circular city embeds the principles of a circular economy across all of its functions, establishing an urban system that is regenerative and restorative by design. In such a city, the idea of waste is eliminated, with assets kept at their highest levels of utility at all times and the use of digital technologies a vital process enabler. A circular city aims to generate prosperity and economic resilience for itself and its citizens, while decoupling value creation from the consumption of finite resources [6]. Amsterdam, one of the leader cities in the application of circular economy concepts to city governance, follows seven principles in its transition toward a circular economy, as elaborated in a report commissioned by the city government [7]:


*Reusable Cities: A Circular Design Approach to Urban Regeneration through Materials Reuse DOI: http://dx.doi.org/10.5772/intechopen.105219*


The abovementioned principles can be extended to define a vision and an action roadmap for circularity in cities.

The "circular city" reduces its environmental impacts from many points of view: from construction-related CO2 emissions to energy production. In the construction sector, a circular city would allow a 10-fold reduction in CO2 emissions and a 75% reduction in soil consumption, with a 30–50% saving in construction costs. Circular construction allows the saving of natural resources, considering that the building and infrastructure sector consumes 1/3 of the world's raw materials, releases 11% of global emissions, and produces 40% of municipal solid waste within demolition processes. It is to be considered that the use of recycled building materials would reduce CO2 emissions by 40–70% [8].

At the global level, the building sector is in fact a crucial one for the implementation of circular strategies, as demonstrated by the survey on the status of the circular economy in 34 cities and regions documented in the Report "The Circular Economy in Cities and Regions" by the OECD [9], where 61% of involved cities and regions declared to have a circular economy initiative including buildings (**Figure 1**).

Planning and design of urban areas and buildings should draw inspiration from the circular processes that occur in nature, by promoting a closed-loop use of resources, and therefore defining flexible, multipurpose spaces, using reused/ recycled and recyclable materials, designing for deconstruction, so as to prevent the production of waste. In fact, in order to successfully deal with the problematic disposal of residues, the very concept of waste must be erased from our design and technological point of view [10], a new circular approach to the design, production, and procurement of materials has to be defined, with the involvement of all the stakeholders, including industry and waste operators.

By resorting to these processes, reproduced in an industrial key, and exploiting the synergy between urban and periurban areas (preferably industrial, to be redeveloped), it is possible to reduce the energy and environmental impact of these areas, rebalancing the impacts of cities.

From the point of view of territorial and urban policies, cities and regions are putting into practice a multiplicity of experimentations of systems and technologies for saving, reusing, and recycling. However, these are largely sectoral practices, still far from the adoption of integrated management and programming models for functions. This integration will increasingly have to bring the various phases of production and management of material and energy flows into coherence and coordinate the activities of the various territorial actors: public administrators, territorial management bodies, producers of goods and services, distributors of goods and distributors of services, users, and workers. The process of adopting integrated models of development and circular management therefore can and must

#### **Figure 1.**

*Fifteen out of 34 cities and regions have a circular economy initiative, where buildings are included in 61% of cases. Source: OECD [9].*

be increased and made more effective through coordinated and decisive support by public governance at the level of all sectors of the national production chains, but above all through the organization and the efficient management of the territory as a generator of economy and consumption in a circular sense [8].

Cities and regions are implementing territorial and urban policies oriented toward a multiplicity of experiments with technologies for reduction, reuse, and recycling, but these practices today tend to be sectoral, far from the adoption of integrated management and programming models for functions. Such integration could, in fact, make the various phases of production and management of material and energy flows coherent, by coordinating the activities of the various actors (public administrators, land management bodies, producers of goods and services, distributors of goods and services, users, and workers). The process of adopting integrated models of circular development and management can be increased and made more effective through a coordinated and decisive support of public governance at the level of all sectors of the national production chains, but above all through the efficient organization and management of the territory, as a generator of economy and consumption in a circular sense [8].

#### *Reusable Cities: A Circular Design Approach to Urban Regeneration through Materials Reuse DOI: http://dx.doi.org/10.5772/intechopen.105219*

What is needed, therefore, is a decisive acceleration in the change of perspective toward circularity: it is necessary to overcome the sectoral, vertical, and fragmented nature that characterizes the circular interventions at the urban scale in the current panorama. Instead, circularity should be considered as central to the eco-systemic and economic functioning of cities and also in their interaction with peripheries, which should be systematically reorganized by putting circularity at the basis of all processes and exchanges of resources that take place at the urban level (food production and consumption, buildings and infrastructure construction, energy production and use, water use and recovery, etc.).

#### **2. The importance of materials reuse in the construction value chain**

The key areas for the implementation of an "urban policy for transition" are mainly oriented toward the reuse and recycling of materials from the building processes and urban value chains (urban mining), through the creation of materials management and recovery hubs and the adoption of reuse practices for the existing building stock [8].

At the EU level, the impacts related to construction activities are even higher than those cited at the global level: the building and infrastructure sector uses nearly 50% of the materials in EU by weight; buildings consume 40% of the EU energy and are responsible for 35% of EU GHG emissions [11]. Indeed, the level of material resource efficiency in the European building sector needs to be improved, in order to increase the contribution of the built environment to decarbonization and circularity, tackling climate change and resource scarcity. Through the Roadmap to a Resource Efficient Europe, already in 2016, the EU emphasized the severe impact of the consumption of raw materials in the construction industry, which represents 50% of excavated materials each year. In addition, the total amount of Construction and Demolition (C&D) waste produced annually in the EU represents almost half of total waste, with a recovery rate that is quite high for many member states, but much uncertain for many others. The necessity to significantly boost the closing of production cycles in the building sector was stated by the EU Dir. 98/2008 on Waste, which called for the increase of reuse, recycling, and material recovery of C&D waste to a minimum of 70% by weight by 2020. This target, which has been achieved by many Member States, among which are Germany, Netherlands, and the United Kingdom, for some countries it is particularly ambitious. The Italian situation, apparently in line with the EU threshold for C&D waste recovery (78.1% in 2019, not considering small quantities of C&D waste that do are not counted and the fly tipped waste) [12], is hindered by the lack of complete and reliable data—due to a partial traceability system—on which to develop an efficient C&D waste policy, by planning appropriate strategies and infrastructures.

However, even the virtuous countries must face a new challenge, highlighted by the abovementioned EU Directive, which places reuse above recycling in the waste hierarchy. In fact, in order to close building materials cycles reducing both energy and material consumption, it is necessary to integrate the two strategies, promoting reuse over recycling whenever possible [13]. At present, while high-quality recycling of C&D waste begins to spread, prevention and reuse, notwithstanding their great environmental and energy potential, are still rare. Both reuse and recycling are valid strategies, but their environmental benefits must be considered on a case-by-case basis. While in the future we ought to use only recyclable or biodegradable materials in buildings, so that they can be infinitely regenerated in a closed-loop model [10], as far as existing buildings are concerned, reuse is often the best option in environmental terms [14]. This is particularly true for clay bricks, stone slabs and blocks, steel elements, and other components with high embodied energy and a low performance decay. The Olympic Park in London represents a best practice in this sense [15]. Reuse, despite being well spread in the past, was almost completely abandoned by the construction industry. It only endures in restoration interventions, particularly in countries such as Italy, which often resort to reuse in the preservation of historical buildings. Nevertheless, in the contemporary circular cities' visions, the closed-loop construction value chain—as envisaged, for instance, in the Amsterdam case (**Figure 2**)—a crucial role is played by all the processes that are needed to allow reuse: deconstruction, selective demolition, separation and stocking of reusable components, eventual remanufacturing, repurposing within other construction sites. This model interprets the urban built environment in the perspective of a "reusable city," with buildings meant as "material banks," a concept deeply investigated in the recent H2020 Research Project BAMB (Buildings As Material Banks) [16].

Moreover, in order to favor a sustainable management of building materials and a higher resource efficiency, there are three crucial factors. Firstly, an accurate quantification of the potential supply and demand of secondary materials on an appropriate area (regional/local scale) is needed. This can help in promoting secondary sources of building materials within the urban planning and in forecasting the withdrawal of resources (such as sand, rocks, and aggregates) from the environment. Secondly, a wide range of tools supporting the operators of the building sector can factually help to implement the eco-effective management of waste materials, such as pre-demolition audits or software for the monitoring of waste production on large construction sites. A third factor, which will pay off in a longer term, is the mapping of secondary sources of materials not coming from building sites but rather from the industry, not necessarily from value chains directly linked to the building sector.

The quantification of supply and demand of inert waste and recycled aggregates at the regional level, experimented in a few studies in literature in the last decade

#### **Figure 2.**

*The vision of a circular construction value chain at the urban/regional scale. Source: Circle Economy, TNO and Fabric [7], redesigned in World Economic Forum [6].*

*Reusable Cities: A Circular Design Approach to Urban Regeneration through Materials Reuse DOI: http://dx.doi.org/10.5772/intechopen.105219*

[17, 18], suggested the possibility to investigate, with a similar approach, the *resource conservation potential* deriving from the reuse of building components and waste materials coming from other industry sectors. This research approach will be described in Paragraphs 3 and 4, while the next sections describe in detail the three above mentioned factors through state-of-the-art experiences.

#### **2.1 The estimation of the stock of materials in the existing buildings on an urban scale: Top-down and bottom-up approaches**

Quantification, at a neighborhood/urban district scale, of the sources for the potential procurement of secondary building materials is a challenging task, to which European countries are starting to approach, in different ways. A good example is Germany, where different valid methodologies are applied, in order to correctly plan the economic and infrastructural development of the recycling industry. Data can derive from statistical analysis on building stock (top-down approach), such as Material Flow Analysis applied to regional level [17]. Data collection can also be carried out by surveying the materials constituting individual buildings (bottom-up approach) and aggregating the data for homogeneous portions of the building stock [18].

Further research experiences on the topic were illustrated within the SBE19 Brussels BAMB-CIRCPATH International Conference, conclusive of the cited H2020 Project BAMB (Buildings As Material Banks) (2019). The most interesting three are illustrated below.

The REBUILD (REgenerative BUILDings and products for a circular economy) Project, coordinated by Exeter University (UK) [19], addressed the possibility of creating value from the remanufacturing of components from buildings that have reached the end of service life (EoSL), creating new construction products destined to buildings to be realized according to the design for deconstruction approach, allowing in the future the potential new reuse of the same components. A key step in this research, in this sense, is the quantification of the stocks of bricks, steel, and concrete in the existing building stock at the district level, as well as the analysis of the related barriers for recovery and reuse. The project focused in particular on the analysis of bricks, with the development of a new technique for the deconstruction of the masonry with the reclamation of the single integral brick in a mechanized way, complemented by a study of the possible transformations of the element itself and of its use in new building components.

Another research, conducted at the Technical University of Munich [20, 21], has instead developed a dynamic GIS/BIM model to evaluate the stocks of materials in urban areas and the relative flows of materials activated by the construction of residential buildings. The research addressed both the classification of materials stocks (land registry of raw materials incorporated in residential buildings) and the identification of future flows of demolition waste, in order to predict potential sources of secondary raw materials, establish recovery strategies and more suitable control mechanisms. The potential supply of reusable/recyclable materials was therefore compared with the demand, in order to identify the degree of self-sufficiency achievable in a given territorial area, reducing the use of primary raw materials and transport. The developed assessment model was validated by applying it to the Munich-Freiham district, one of the main urban developments in Germany, demonstrating that a self-sufficient supply of steel (from 2036) and recycled aggregates for the production of concrete (from 2031) can be achieved for the construction of residential buildings.

Finally, another interesting research, developed in Belgium by the Hasselt University with the real estate company Essencia [22], experimented the use of existing databases as a tool to explore the potential of the building stock as a bank of materials. The research reports an estimate of the quantities of materials present in the residential building stock in the Flanders region, based on the combination of two existing databases: one relating to the energy performance certificates of buildings, belonging to the Flemish Energy Agency (VEA), with the general characteristics of the buildings, such as volume, type, surface, and information on the envelope of over 1 million assets in the Flemish region; the other one, developed by Essencia Marketing, containing general characteristics, geometric data, and materials on nearly 6000 new residential buildings distributed throughout Belgium. The research examined both databases and defined methods for combining data and for assessing the (future) potential of the existing building stock as a bank of materials.

#### **2.2 Tools for the quantification of waste materials at the building site level**

The tools supporting designers and operators (construction and demolition companies) in the estimation, monitoring, and exchange of waste materials in the design and construction phases play a crucial role in optimizing the level of material resource efficiency and circularity in the construction sector.

In the United Kingdom, for example, the share of C&D waste diverted from landfill has significantly grown thanks to, among many regulatory instruments, the mandatory introduction of Site Waste Management Plans in 2008. These Plans, containing an estimate of the waste that will be produced, as well as the accounting of waste actually produced, provide an accurate data collection in real construction/ demolition projects, which can effectively integrate statistical surveys. In England, the collection of data is facilitated by the SMARTWaste program by the BRE [23], an online tool supporting operators in the preparation of waste management plans and in the monitoring of waste on site. The SMARTWaste database enables operators to verify and increase their resource efficiency over time, while simultaneously providing valuable information to public authorities for the optimization of this sector. Such instruments could help those countries, such as Italy, still uncertain on the real quantity of C&D produced/recovered.

Another interesting initiative, with a view to the digitalization of the management of building materials' recovery processes—aimed at optimizing their environmental and economic sustainability—was the publication in Italy of the Reference Practice UNI/PdR 75: 2020 "Selective deconstruction—Methodology for selective deconstruction and waste recovery from a circular economy perspective" (February 2020) [24]. This technical pre-standard aims to define a macroprocess for deconstruction that favors the recovery of C&D waste and is oriented toward the compatibility with the digital management of the process itself and of the materialrelated information. The envisaged process takes into consideration both existing buildings to be refurbished or demolished and new constructions: for the former, through a pre-demolition audit, a database of materials intended for recycling and reuse is built and used during the intervention; for the latter, it is necessary to compile the database of the materials foreseen by the design project. The deconstruction process is divided into three phases: planning, operational, updating the database/final list of the materials used in the building. The aim of this procedure set by the UNI/PdR is to overcome the difficulties of the current construction waste tracking and management system, which in Italy appears to be a barrier for a concrete practicability of circular strategies. Within the UNI working group, the GEOWEB company offered its contribution on the subject of digital support tools for operators, creating a mock-up that collects instruments and functions covering the following phases: survey; modeling of the three-dimensional geometry of the building; design, planning, and execution of the deconstruction intervention.

#### *Reusable Cities: A Circular Design Approach to Urban Regeneration through Materials Reuse DOI: http://dx.doi.org/10.5772/intechopen.105219*

The SaaS (Software as a Service) platform supports an end-to-end workflow in which all waste management technical and administrative phases are acquired, processed, planned, validated, and certified. Furthermore, the platform integrates an operational network of services (transport, waste treatment, storage, sale of products from secondary materials) offered by local companies, thus providing information and interoperability tools enabling stakeholders to monitor the process on the territory, to enforce policies, to define capacity planning processes, and finally, to promote incentives for the implementation of circular practices.

Another example of a tool to support the actors of the construction process for enhancing the use of secondary materials is the DECORUM platform, developed in Italy by ENEA [25]. The Platform, in support of all the actors of the supply chain in the decision-making phases, aims at ensuring the compliance of construction/ renovation works with regulatory and environmental requirements, in particular with the mandatory national Green Public Procurement Minimum Environmental Criteria (GPP MEC) for Buildings (Ministerial Decree 11/10/2017) defining minimum thresholds of recycled content for the different building materials/products. Moreover, the marketplace section of the Platform gives space to the availability and reliability of recycled materials, promoting their wider diffusion in public works contracts.

Finally, the recent French initiative, which saw the development of the Démoclès platform, should also be mentioned: Démoclès is a traceability model for construction waste, whose methodology is being tested in France to be then disseminated abroad. In fact, the feasibility study [26] of the platform established a European benchmark to identify best practices in terms of traceability for—but not only construction waste, demonstrating that there are two types of possible tracking systems: those similar to certifications and those that physically track streams accompanied by documents and a "third party guarantor." Furthermore, the study identified the building industry's needs in traceability and allowed the definition of specifications for a specific system, revealing that only a physical traceability of streams would be able meet stakeholders' requirements and enabling the construction of the system and of the Démoclès platform.

#### **2.3 Harvest Maps at the urban district and city level**

As mentioned, the most innovative research experiences concerning the design of buildings with a low consumption of raw materials today focus on the reuse of materials and components, not necessarily from the building sector, following an urban mining approach. In particular, some research studies have proposed and experimented the mapping of local sources of reclaimed materials, suitable for architecture but coming from other waste streams, before the designing of the building itself [27], those promoting the valorization of residues *through* the design solution. Indeed, reuse provides not just cultural and esthetic benefits, but concrete environmental and economic advantages, whose potential deserves to be thoroughly investigated.

The process set out by Superuse Studios (NL, formerly 2012 Architecten) is a fundamental reference for the circular project, because it involves sourcing all types of waste materials locally and enhancing their potential through a new design and construction process: the demolition of an existing building can represent the first source of materials; then, sources of other types of waste are sought in the proximity of the project area, opening up to the flows of discarded materials at the urban district and the city level. The project experience shows how it is possible to identify different mines of materials, each one characterized by its own dynamics, referring to different types of residues: End of life cycle products/materials

(waste), Construction and demolition (waste), Dead stock (new), Production waste (new), Fast-life (short use). All of these potential sources are geo-referenced creating a graphic map with an overview of the residual materials reused/reusable in the project and their original locations. The map is called "Harvest Map" and its use, within the design process, allows many benefits [28].

The scouting process of waste materials [27] suitable for use in architecture (byproducts, defective products, dead stock, leftovers processing waste, C&D waste, etc.) and available in the area adjacent to the intervention site, within a limited distance—on average a radius of 25 km—allows the enhancement of local waste by design, with actions of "superuse" rather than simple reuse, where materials acquire a more relevant technical and esthetic value through the design process. Moreover, this process allows to reduce the energy and carbon embodied in the materials used for the intervention, to avoid consumption and emission for the production and transportation of "new" materials, as well as at to activate small-scale circular economy processes. The research experiences described in the next paragraphs investigate the implications of this early mapping of the materials available on the site of the project, both in terms of optimization of resources use and of material characterization of architecture and the potential for transposing this strategy into a highly repeatable technical option [29].

#### **3. Hypothesis and research objectives**

The present contribution reports the results of research activities whose aim is to supplement ongoing studies on environmental benefits of recycling in the building sector, by investigating the potential of reuse to increase the overall eco-effectiveness of construction interventions. The hypothesis to be tested is that for a real reduction of primary materials consumption in the building sector, we need to place side by side the use of secondary materials with two other modalities of supply: the reuse of building components resulting from the partial or total deconstruction of buildings, and the reuse of materials from other waste streams not belonging to the construction sector. Therefore, the reported research activities have tried to understand to what extent the reuse of architectural components and waste materials from other industries can help to increase the resource efficiency at the local scale, reducing the consumption of materials, land, and energy. Final aim of the research is to decline the "circular city" in a specific perspective that of the "reusable city," where the built environment represents a resource to be reused in closed loops of material flows. In order to understand to what extent reuse might integrate C&D waste recycling (in particular that of inert waste, representing the main fraction) and to define the potential for resource conservation related to reuse itself, it is necessary to analyze real contexts to understand the actual availability of discarded materials and components suitable for architecture. In this sense, the points at issue are: the frequency of partial and complete demolitions in town; the instruments that a designer or a contractor can adopt to search for reusable materials; the tools that can be used to signal the availability of materials; the possibilities of activating new and different flows. Given the variety of types of materials from other sectors, which might be adopted in construction, it is necessary to focus on stable flows, constant in time and space, which in some cases can be even more regular than those coming from demolition activities, typically not constant in time and not completely predictable. Specific industrial activities might instead represent a constant source of by-products for the building industry.

The specific research goal is to investigate how reuse can contribute, at the scale of an urban district—and then scaled up at the city level—to reduce raw materials

*Reusable Cities: A Circular Design Approach to Urban Regeneration through Materials Reuse DOI: http://dx.doi.org/10.5772/intechopen.105219*

consumption, waste production, energy, and emission in the production and transportation of building materials and components. The scale of investigation has been chosen in order to minimize the impacts of the transport of building materials. Therefore, the research studies have focused on case studies of urban regeneration at the district level, testing the potential impacts of reuse on the life cycle first of a single building, then of a small group of buildings, and identifying, in the end, the factors that make it possible to scale up the results to the urban level. The chosen building has undergone a complete technological breakdown in order to understand, within the deep retrofit scenario, which technical elements are more suitable to be renovated with reused materials. Using a life cycle thinking approach, the average length of the service life of various technical elements, the average frequency of replacement of components, and the duration of the service life of the building as a whole have been taken into consideration. Then the materials requirements haven been considered in order to identify potential secondary/reusable materials available at the local level, taking into account the embodied carbon indicator in order to identify the best option in environmental terms, by quantifying the reduction of CO2 emission due to the avoided extraction, production, and transportation. This is useful also in order to compare multiple scenarios: the use of primary raw materials, of reclaimed components and recycled materials, of only recycled materials. After evaluating the benefits on the single building, it is necessary to assess the possibility of extending reuse to the building stock at the urban scale, in order to maximize its environmental potential.

Final aim of the research is to develop a procedure (and related verification indicators) supporting the design phase. Thus, the scope in the long term is to facilitate the adoption of reuse as a strategic technical option. These objectives require an interdisciplinary and multiscalar approach, combining different scales of investigation (from the city to the building to the component level) and multiple methods, in order to respond to a new and broader approach to resource efficiency in the building sector.

#### **4. Research methodology**

The research methodology is divided into three main phases carried out with specific methods. In order to test the hypotheses defined above and to reach the mentioned objectives, it is necessary to start the analysis at the urban level. The adopted model works on the multiscalar dimension of urban districts, with the aim of redefining the environmental, energy, and social performance of existing quartiers to be turned—through urban regeneration—into circular districts, characterized by high resource efficiency and closed-loop flows of material and immaterial resources, in line with the objectives of decarbonization and climate neutrality. In this approach, the renovation interventions aim at a high level of material resource efficiency in the optimization of the environmental performance of the existing settlements, in order to limit the consumption of raw materials, favoring the supply of "zero km" and/or locally sourced building materials and products and at the same time minimizing the volume of C&D waste through circular strategies, thus reducing the level of embodied carbon in the materials used (**Figure 3**). The renovation of existing buildings themselves is a strategic action in order to reduce the need for materials and limit environmental impacts, both in the short and long terms adopting the Design for Deconstruction strategy.

The first phase of assessment of the adopted methodology involves the identification of the building components and materials that make up the building, the estimation of their volume and weight, and the calculation of the carbon

#### **Figure 3.**

*Circular design process implemented in the design of the linear buildings and the outdoor spaces in the Torrevecchia District, Rome (IT). Source: Research Studies, S. Baiani, P. Altamura with M. Battiata, G. Schiavon, A. Sofi (2021).*

embodied in the single materials, starting from a relevant reference database. At the same time as defining the design solutions for the rehabilitation of existing buildings, the volume and weight of the materials destined to be removed from the various technical elements and the relative estimate of the embodied carbon are also quantified.

#### *Reusable Cities: A Circular Design Approach to Urban Regeneration through Materials Reuse DOI: http://dx.doi.org/10.5772/intechopen.105219*

From a methodological point of view, the evaluation of the level of material resource efficiency achieved is identified through consistent quantitative indicators that allow the measurement of the effectiveness of the choices. In particular, it is possible to measure the recycled content of the materials chosen for the intervention (one of the criteria of the GPP Minimum Environmental Criteria for Construction, compulsory at national level since 2016 for the entire public built heritage); the rate of landfill diversion of materials removed from the existing building; the amount of material recovered on-site; the amount of embodied CO2 preserved by avoiding the demolition of existing buildings and that preserved through the recovery of materials intended for disposal, in particular on-site reuse or recycling that avoids energy consumption and emission due to transport.

For individual components and materials, potential circular technical options to avoid landfilling are assessed, with reuse as the preferred scenario over recycling and on-site reuse as the optimal solution. The different technical options are compared considering environmental, technological, and economic costs and benefits (**Figure 4**).

The process outlined leads to the integration of three different ways of supplying the materials needed for the deep retrofit intervention: the identification of components that can be recovered from the renovated buildings, during the selective demolition phase (e.g., external and internal fixtures), and that can be subject to remanufacturing and reuse or to recycling and reuse in situ; the identification of sources of waste materials/components/products from buildings or industries in the surrounding area; the selection, to cover the remaining needs, of new renewable and certified materials, which support the objective of reducing environmental impacts and intervention costs, while also ensuring the future reusability and recyclability of materials: "Changing the way products and materials are selected, manufactured and used in the built environment can lower environmental impacts as well as costs. Biological nutrients and sustainable, renewable materials can replace materials that are heavily processed, and hard to reuse and recycle" [30].

It is possible to define the mapping of the sources of waste materials coming from other supply chains (Harvest Map, **Figure 5**), built through an online survey and direct contact with companies, through the provision of questionnaires and inspections aimed at viewing the stocks of materials (surplus, waste, defective products, processing residues, etc.) potentially recoverable in the redevelopment intervention [31].

As part of the experimentation in the urban district of Torrevecchia, in Rome (Italy), online surveys were, as a priority, conducted to identify potential local mines, which were subsequently investigated directly, in collaboration with the respective operators, in order to identify potentially reusable materials. The research led to the definition of a GIS-based map, which identifies potential sources with their inventory of materials, their performance characteristics, and potential uses in relation to the technical elements identified by the project.

The experimentation has identified different typological systems characterizing public housing (ERP) assets (towers and linear buildings) on which the mass flow balance has been developed, considering all the inputs and outputs of materials expected to occur in rehabilitation and maintenance interventions during the whole life cycle.

Through a technological breakdown, with direct surveys and archive research, the technical elements that, on the basis of the project, can be replaced/integrated with recovered components being identified. The evaluation was supported by comparison with projects and experiments that have adopted, with a similar approach, mixed systems containing recovered materials. Through the comparison with case studies, the elements for which the application of reusable components

#### *Sustainable Development Dimensions and Urban Agglomeration*

**Figure 4.**

*Torrevecchia District in Rome: Circular building process and its quantitative verification. Research Studies, S. Baiani, P. Altamura, with N.D. Belforte and C. Fabrizio (2021).*

is technically, economically, and environmentally more feasible were selected and analyzed in terms of technical requirements and potential performance (**Figure 6**).

An important step in the experimentation is the possible identification of resources on an urban and local scale, starting from demolition materials, reasoning on other types of waste, working on the production of energy at a local level and the reduction of transport emissions, due to the limited size of the district.

*Reusable Cities: A Circular Design Approach to Urban Regeneration through Materials Reuse DOI: http://dx.doi.org/10.5772/intechopen.105219*

#### **Figure 5.**

*Harvest Map around the Torrevecchia District, Rome: Map of the companies identified as sources of waste materials around the regeneration site of the Torrevecchia District, within a radius of 6 km. In red, the companies whose waste materials have been chosen for the project. Source: Research Studies, S. Baiani, P. Altamura with M. Rossi and S. Urbinati (2019).*

The innovative character of the project lies in the way it verifies the feasibility of reuse in an urban area—and not on an experimental architectural project—to build a dataset that can be used by designers and can be increased by individual users, through shared tools such as the open-source Harvest Map platform. An initial mapping, available to operators in the building industry for the sector, could

#### **Figure 6.**

*Technical systems and subsystems of one of the renovated linear buildings in Torrevecchia, Rome: Disassembly of the elements built with reused and recycled materials. Source: Research Studies, S. Baiani, P. Altamura, with N.D. Belforte and C. Fabrizio (2021).*

in the future make it possible to direct the methods of intervention, representing a picture—continuously updated—of the material resources available, with significant spin-offs in terms of innovation, involving all the operators in the process.

The experimentation phase, carried out on real cases, examined the potential sources of reusable materials in the city, starting from large construction, demolition, or redevelopment sites. The screening was carried out in an area with a radius of 10–20 km around the project sites, extending the research to more distant areas only in case of specific project characteristics. In the area of the former industrial site Papareschi in Rome (MI.REUSE Project, 2018) [31], for example, the project—aimed at the recovery of the former Miralanza factory with the use of waste materials sourced on site—applied a process that from the scouting phase led to the creation of a Harvest Map, to the redefinition of functions and spaces and the technological design of reversible building components with reused materials [29].

The results achieved in the different contexts, in terms of circular management of building materials in the intervention phase, denote a potentially very high level of circularity achievable through the management of building materials, deriving from partial demolitions and supplied for rehabilitation interventions. Interesting data, derived from experimentation on an public housing urban district in which for each building about 50% of the existing materials are conserved and the remaining half are destined for selective demolition, demonstrate the possibility, through the integrated action of several technical options for the end of life of materials, to reach a recovery quota of materials destined for demolition of about 90% by weight (higher than the 70% threshold of the EU Dir. 98/2008, which GPP MEC have adopted as a criteria) that guarantees to preserve about 80% of the embodied carbon of the materials intended for demolition, which replace new materials for the sub-bases of the external paving, whose environmental impacts are avoided [32].

The investigation involved gathering knowledge about the site in terms of the changes and transformations that led to its current state. Evaluating the building's evolving use has highlighted a series of transformations, which have affected the existing structure at different points in its life cycle. These changes are mainly related to past needs to expand overall living space. A building's life cycle can be analyzed by reading and understanding its construction system. This also makes

it possible to understand its peculiarities and limits. In the Torrevecchia District in Rome, in terms of the architectural and construction aspects of the building system, it was made using a heavy and prefabricated system in reinforced concrete (**Figure 7**). This was completed with panels made off-site, limited interior insulating materials and plaster finishes.

#### **Figure 7.**

*"Ante operam" state of a renovated building in Torrevecchia, Rome, with the quantification of demolished materials in weight, volume and embodied carbon and the identification of circular design strategies and estimate of the recovery rate. Source: Research Studies, S. Baiani, P. Altamura with F. Ianiri, G. Massaroni, N. Taddei (2020).*

#### **Figure 8.**

*Design solution for a renovated building in Torrevecchia, Rome, with the quantification of the intervention's materials in weight, volume, and embodied carbon and the calculation of the recovery rate of demolition materials and of the embodied carbon preserved through reuse. Source: Research Studies, S. Baiani, P. Altamura with F. Ianiri, G. Massaroni, N. Taddei (2020).*

A comparative assessment was also subsequently conducted to consider the potential effects of resulting demolition waste (in terms of volume/weight). The overall material requirements were also considered under more or less "invasive" intervention scenarios in terms of expanding demolitions/additions. Under these

#### *Reusable Cities: A Circular Design Approach to Urban Regeneration through Materials Reuse DOI: http://dx.doi.org/10.5772/intechopen.105219*

scenarios, various operational choices led to different comparable options based on redefining the housing, introducing/increasing common spaces or living services and identifying components to eliminate or integrate. However, each scenario commonly reflected the guiding technical requirements that interventions be totally reversible, low cost (in terms of environmental, energy, and economic impacts), and material minimizing (in terms of weight and types of materials used).

Estimates were done on materials to be removed from the building in terms of weight and volume, and associated embodied carbon was included in these measurements as well. Estimates were also made in terms of the volume of materials needed to execute each different scenario (these materials were selected based on a set of performance criteria that included maximum decarbonization). This made it possible to come up with a matrix of technical systems, components, and materials, which permitted considering "materials to look for" versus "materials to let go." The Harvest Map was consulted to this end to identify supply "mines." Defining technical systems for each of the options identified (addition, integration, grafting, replacement) has made it also possible to evaluate which existing elements could be recovered and reintroduced over the building life cycle. It also affords systematizing processes of disassembly, micro-demolition, and material or component replacement and recovery. It additionally permits calculating the material/component shares (in terms of percentage by weight and volume), which may come from on or off-site sources. This all made it possible to develop technological solutions while applying a "circular" and "reversible" view of the various elements involved. In doing this, particular attention was paid to the building envelope and the "passive" bioclimatic control devices to be introduced. To this end, verification of energy effectiveness took place as well, alongside with the assessment of the embodied carbon indicator (**Figure 8**).

#### **5. Results discussion and conclusions**

By assessing the technical feasibility and environmental potential of adaptive reuse in an urban context, based on the available sources of secondary materials, the experimentation demonstrates the transferability of this strategy in different contexts. This is achieved by proving its significant effectiveness and relevant potential contribution to decarbonization and resources conservation targets. It is possible to identify some specific contributions of the research work, at different levels.

First, the identification of the instrumentation to support the development of a circular design methodology that focuses on the action of recovery and reuse (buildings, components, materials) in order to evaluate how reuse can contribute, at the scale of an urban district—and then scaled up at the city level—to reduce raw materials consumption, waste production, energy, and emission in the production and transportation of building materials and components. In particular, the tools supporting designers and operators (construction and demolition companies) in the estimation, monitoring, and exchange of waste materials in the design and building phases play a crucial role in optimizing the level of material resource efficiency and circularity in the construction sector. Among these: the Site Waste Management Plans (UK) containing an estimate of the waste that will be produced, as well as the accounting of waste actually produced, providing an accurate data collection in real construction/demolition projects, which can effectively integrate statistical surveys; the Reference Practice UNI/PdR 75: 2020 "Selective deconstruction—Methodology for selective deconstruction and waste recovery from a circular

economy perspective" (IT) with a view to the digitalization of the management of demolition waste recovery processes, aimed at optimizing their environmental and economic sustainability; the DECORUM platform (IT) supporting the actors of the construction process for enhancing the use of secondary materials; the Démoclès platform (FR), a traceability model for construction waste. Among the tools assessed in the research activities, the Harvest Map was identified as a fundamental reference for the circular project, because it involves sourcing all types of waste materials locally (mines) and enhancing their potential through a new design and construction process.

Second contribution of the research work was the development of a methodological and operational structure, also based on the transfer of international experiences, appropriate to the Italian context, with an experimental approach for the verification of the phases and the evaluation of the results achieved.

Thirdly, through the systematic identification, for each building typology, of elements and technical systems suitable for the realization with reclaimed components, the research validated the compliance of reclaimed elements and materials with specific requirements, with a performance verification procedure.

One potential research perspective opens up, in the definition of an appropriate methodology for the identification and "promotion" of reclaimed components in the urban environment, with a focus on the characterization of virtual and physical spaces (hubs) where materials can be collected and shared with potential users. These local hubs, developed on the basis of the potential demand, which is difficult to correlate with the supply, could constitute an advanced system that could also favor the on-site production of technical components, reducing the considerable impacts caused by transport. The possibility to foresee the potential impact of a greater use of reused materials and components in the building industry favors the reduction of the demand for new materials and opens up new design opportunities in regeneration interventions.

This defines a design vision that focuses on "circularity" in its broadest sense, capable of characterizing the multiple phases of the life cycle of an urban district, through the circular use of materials from regeneration and construction interventions and integrated management of ecological and energy systems, in the broader vision of "reusable cities."

#### **Author details**

Serena Baiani\* and Paola Altamura Planning Design Technology of Architecture Department, "Sapienza" University of Rome, Rome, Italy

\*Address all correspondence to: serena.baiani@uniroma1.it

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Reusable Cities: A Circular Design Approach to Urban Regeneration through Materials Reuse DOI: http://dx.doi.org/10.5772/intechopen.105219*

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[13] Addis B. Building with Reclaimed Components and Materials. London: Earthscan; 2005

[14] Sassi P. Designing buildings to close the material resource loop. Engineering Sustainability. 2004;**157**:163-171

[15] Hartman H. London 2012 Sustainable Design. Delivering a Games Legacy. Chichester: Wiley; 2012

[16] H2020 Building As Material Banks [Internet]. 2019. Available from: https:// www.bamb2020.eu/. [Accessed: 13 February 2022]

[17] Schiller G, Deilmann C. Ermittlung von Ressourcenschonungspotenzialen bei der Verwertung von Bauabfällen und Erarbeitung von Empfehlungen zu deren Nutzung. Dessau-Roßlau:

Umweltbundesamt; 2010. Available from: http://www.uba.de/uba-infomedien/4040.html

[18] Volk R, Stengel J, Schultmann F. Compilation of regional building stock inventories under uncertainty. In: Proceedings of the SB 13 Singapore. Realising Sustainability in the Tropics. Singapore: Research Publishing; 2013. pp. 493-500

[19] Ajayabi A, Chen HM, Zhou K, Hopkinson P, Wang Y, Lam D. REBUILD: Regenerative buildings and construction systems for a circular economy. In: Buildings As Materials Banks. A Pathway for a Circular Future. SBE19 Brussels BAMB-CIRCPATH. Brussels: IOP Conference Series EES 225; 2019

[20] Heinrich MA, Lang W. Capture and control of material flows and stocks in urban residential buildings. In: SBE19 Brussels BAMB-CIRCPATH. Brussels: IOP Conference Series EES 225; 2019

[21] Heinrich M. Erfassung und Steuerung von Stoffströmen im urbanen Wohnungsbau—Am Beispiel der Wohnungswirtschaft in München-Freiham [thesis]. Germany: Technical University of Munich; 2019

[22] Gepts B, Meex E, Nuyts E, Knapen E, Verbeeck G. Existing databases as means to explore the potential of the building stock as material bank. In: SBE19 Brussels BAMB-CIRCPATH. Brussels: IOP Conference Series EES 225; 2019

[23] Adams K, Blackwell M, Holt A. Saving Money, Resources and Carbon through Smartwaste. Watford: IhsBrePress; 2013

[24] Reference Practice UNI/PdR 75: 2020 "Selective Deconstruction— Methodology for Selective Deconstruction and Waste Recovery from a Circular Economy Perspective". February 2020. Available from:

https://www.bauschutt.it/ media/9af07049-6542-494a-9f3f-49a743d64595/uni21001058-eit.pdf. [Accessed: 13 February 2022]

[25] Luciano A, Cutaia L, Cioffi F, Sinibaldi C. Demolition and construction recycling unified management: The DECORUM platform for improvement of resource efficiency in the construction sector. Environmental Science and Pollution Research. 2021;**19**:24558-24569

[26] Elcimaï, Girus, Terra, RDC Environment. Démoclès. Étude préalable d'un dispositif de traçabilité des déchets de chantiers du bâtiment. 2019. Available from: https://www. democles.org/uploads/2020/01/ democles-rapport-etude-tracabilite-vf. pdf. [Accessed: 13 February 2022]

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[32] Tucci F, Baiani S, Altamura P, Cecafosso V. District circular transition and technological design towards a circular city model. Techne. 2021;**22**: 227-239

#### **Chapter 11**

## The Street Edge: Micro-Morphological Analysis of the Street Characteristics of Baghdad, Iraq

*Haider Jasim Essa Al-Saaidy*

### **Abstract**

In Arabic cities, diversity can be seen in the development of the same underlying order. This assists to manage to qualify well-defined relationships with various levels of movement in the urban setting. The micro-morphological examination is used to emphasise further the spatial pattern at a micro-level within a macro-scale scope. Hence, micro-level studies are essential in evaluating the built environment with regard to private and public domain. Terminologically, the notion of the symbiosis of how the private and public domains interact with each other is needed. Also, there is a need for people to know their rights when using the street edge and the extent to which they (the owner/user) have the authority to modify the public space. The transition of the urban pattern from the traditional order (spontaneous pattern) to the modern model (pre-planned system) not only changes the spatial morphological structure entities but also transformed the association of the private and public domain.

**Keywords:** street pattern, private control, public control, traditional (spontaneous) order, modern (pre-planned) system, urban symbiotic relationship

#### **1. Introduction**

The pattern (Edge–Edge interface) is controlled by morphological parameters that manage the street network regarding the binary element: plots and blocks. The level of superposition between the two domains is evaluated by various indicators based on the specifications of the street pattern. According to Al-Saaidy [1] 'the assets of Baghdad today belong to this historical period of the city with its significant monuments and organic street pattern. Otherwise, the urban areas that settled outside the historical zone were designed according to a modern scheme and a modernist ideology' ([1], p. 6). Moreover, Marshall [2] confirms that 'land use zones and roads, in a modernist urban structure, [are] represented separately as nodes and links, but in a traditional urban street network, the streets themselves are significant spatial entities' ([2], p. 112). The mechanism in operating the street edge differs when it comes to comparison between two patterns: traditional and the modern network. The convergence between the individuals and their adjacent edges, which mostly relates to the street life and social interactions. The pattern

(Edge–Edge interface) is also responsible for defining the boundary between two realms, private and public. The degree of overlap between the two territories is measured by different indices based on the characteristics of the street edge, such as porosity, transparency and permeability (**Figure 1**).

Using a fine-scale analysis by examining the street pattern seems to be a more effective means of understanding the urban characteristics of streets over largescale classifications. There is a definite pattern of activity about the order process of compound parameters, which increases in an area or within set spatial dimensions. Conversely, large-scale order is influenced by minimum or single settings, and this due to the comprehensive analysis system of streets, which are expected to be unrelated in formulating distinguishing urban characteristics for the city [1, 3–5]. Morphologically, the leading characteristics of Baghdad Street pattern combine variety and difference between the pristine and new model. Both patterns, historical and modern, are managed by two distinct generative orders: spontaneous (bottom-up approach) and pre-planned (top-down procedure) [1].

Recently, the debate is not only between conventional and modern concepts in urban studies but also what can be understood between two domains: private and public in formulating street edge [6]. Micro-level explanations are essential in evaluating the adjacent edges of a street. The notion of a symbiotic relationship between private and public spaces, with the effectiveness of street life, plays an essential role in advancing the quality of social interaction. In this article, knowing the affiliation of the spatial attributes at a micro and macro scale needs an interpretation of how spatial ingredients in an urban environment are placed. There could be a range of expectations when the community uses the private and public realms. These two domains express individual action and group behaviour. The shared beliefs, norms, values, economics, politics and the natural and built environment, these considerations are the predominant aspects of living in a particular community [7, 8].

**Figure 1.**

*The fictive image illustrates the interface between two opposite street edges. Source: Drawn by the author.*

*The Street Edge: Micro-Morphological Analysis of the Street Characteristics of Baghdad, Iraq DOI: http://dx.doi.org/10.5772/intechopen.102403*

#### **2. Responding to the urban edge**

The manner in which a community, particularly in Iraq, manages public spaces could lead to a spectrum of opportunities that inform individual action and collective behaviour alike. Primarily, human behaviour tends to conform to the predominant dimensions of living in a particular community, for example, by embracing the common beliefs, norms, values, economics, politics and the natural/built environment. In this regard, Bianca [9] states that the physical environment represents, '… every genuine cultural tradition, architecture and urban form' and that this '… can be seen as a natural expression of prevailing spiritual values and beliefs …. it is an outcome of tradition and daily practices which correspond to certain spiritual principles' ([9], p. 22). These factors embed the interrelationship between space, time and culture. Moreover, the tripartite connections among these three social parameters (sociocultural, sociophysical and socioeconomic) are rooted in and formulate both the ecological pattern and different responses to the surrounding environment (**Figure 2**).

Even though there are different urban patterns, people who perceived the public spaces shared the same cultural patterns but not the same behavioural actions. The observation is based on the ethnographic method and quantifies the responses of people who use the street. This technique facilitated the documentation of people's responses and interactions without any interference or effect on the subjects' actions. In this regard, to a large extent, the historical and traditional area in Baghdad grants an opportunity for persons to share the public space and involve in such activities as walking, staying, sitting, standing, watching and chatting where the street edge works to interconnect the accommodation of such activities [10, 11].

In the contemporary neighbourhoods, the lost knowledge of public and semipublic or semi-private spaces can be experienced in various ways. Moreover, in modern areas, the human scale, enclosure and definition, and the authority of its public space are missing (**Figure 3**). As the public space can be distinguished according to the activity pattern of the adjacent context, it is possible to recognise different types of more common street edges, such as residential, commercial and mixed (**Figure 4**).

#### **Figure 2.**

*The tripartite connection among three social parameters (sociocultural, sociophysical and socioeconomic), which are governed by spaceandtime. Source: Drawn by the author.*

#### **Figure 3.**

*In the modern pattern, some public spacesare not within the authority of residents, where there is no explicit declaration about the claim overthis type of territory. Source: Photographed by the author's team, 12/ December/2016.*

#### **Figure 4.**

*Residential edges: Multi-storey residential areasversus traditional low-rise neighbourhoods. Source: Photographed by the author's team, 12/December/2016.*

These edges are entirely responsible for shaping people's responses, particularly within residential areas where people react spontaneously to the private, semiprivate and even semi-public realms (**Figure 4**). Inhabitants in these areas tend to change the characteristics of the semi-public and sometimes public spaces. These changes manifest differently, such as through soft treatments or hard borders when a resident illegally occupies the adjacent realm (**Figure 5**). However, the residential edges are likely to be used by their inhabitants even if these edges face the public space or link directly to the street. Moreover, some proprietors cut off the adjacent part of the street in order to change the primary land use from residential to commercial. Unfortunately, this transformation of purpose, and any misunderstanding of the rights to do so, leads to uncharted changes in land use. Hence, the residential edge is then be used for walking through rather than as a place to stop. According to Alexander [12] and Hillier et al. [13], a street is generally designed for staying in, or movement-to rather than movement-through.

On the commercial and mixed edges, lively interactions between the people and street spaces are experienced. Although these edges, particularly in the historical area, are still lacking in maintenance, they represent an attractive spine for the neighbourhood (**Figure 6**). People who benefit from this type of edge show different responses based on the particular activity of each unit along with the adjacent edge. Those who use public space can be classified according to their two primary activities: walkers and stayers. The aims of these two classes are varied in terms

*The Street Edge: Micro-Morphological Analysis of the Street Characteristics of Baghdad, Iraq DOI: http://dx.doi.org/10.5772/intechopen.102403*

#### **Figure 5.**

*Inhabitants have dealt with the public edge by turn it intoa private space. Source: Photographed by author's team, 08–13/December/2016.*

**Figure 6.** *The commercial and mixed edgesin samples a (left) and D (right). Source: Photographed by author's team, 12–21/December/2016.*

of their exchange purpose and/or movement-to/movement-through [6, 14]. The expression of public space and its investments differ considerably between the traditional area and the more modern design. Whether in the traditional or modern area, the quantity of the public spaces is generally required, except in the areas offered by the adjoining edges.

Therefore, there is a need to not only examine the traditional part of a city as an isolated pattern but also to understand the comparison with other, new neighbourhoods in terms of the different perspectives afforded, particularly via the urban form and urban life. The traditional urban fabric arose in response to indigenous cultures and traditions; thus, Remali [15] explains that the 'traditional urban form is the result of [the] "selectionism" of an evolutionary process, whereby a built environment gradually become[s] congruent with activity systems, lifestyles, meaning and values by applying rules, which are often unwritten, as in most cultural landscapes' ([15], p. 57). Moreover, there is also a need for individuals to understand their rights when using the street space and the extent to which they (the owner/user) have the authority to alter the public space. Commonly, individuals tend to extend their territoriality, even in temporary activities. This includes peddlers and the owners of adjacent units (shops) who tend to extend the commercial edge by elongating the boundary of their activities. These expansions differ entirely from one individual to another, and from one street to another. One of the main reasons for such territorial extensions is to attract customers by making the adjacent spaces particularly enticing; nevertheless, a critical issue remains concerning the authority for these expansions.

### **3. Edge: Edge Interface**

#### **3.1 Interfacing between street and private-public edges**

The main question is 'to what extent individualistic lifestyles can interfere with street life and vice versa' ([16], p. 2). The relationship between private and public would exist within a micro-spatial configuration. Van Nes and López [16] state that the main street network in the urban context is a factor that influences the microscale spatial variables. Spaces that mediate between buildings and streets create social interactions, which help to form human behaviour. These spaces could be part of a buildings' interior that causally link with the public space, such as courtyards and balconies or through spaces in front of buildings, such as sidewalks. They encourage a social encounter and promote street life at different levels, whether in terms of culture, norms and religion or the physical conditions of the built environment [17, 18] (**Figure 7**). According to Jacobs ([19], p. 59), a relationship between the private and public realms requires 'a good city street neighbourhood [that] achieves a marvel of balance between its people's determination to have essential privacy and their simultaneous wishes for differing degree of contact, enjoyment or help from the people around'. According to Marshall [20], the relationship between private and public is neither only determined through physical expression, nor a volumetric enclosure that regulates the public-private border, but rather functions as a social filter.

Marshall ([2], p. 13) states that 'the movement space constituted by streets forms the essential connective tissue of urban public space – from the micro scale

*Transforming outdoor space activities into indoor space activities from ancient to urban settlement. Source: Nooraddin [18].*

#### *The Street Edge: Micro-Morphological Analysis of the Street Characteristics of Baghdad, Iraq DOI: http://dx.doi.org/10.5772/intechopen.102403*

of circulation within building to the macro scale of whole cities'. Therefore, 'street space forms the basic core of all urban public space – and by extension, all public space – forming a continuous network or continuum by which everything is linked to everything else. This continuum is punctured by plots of private land. The plots of private land surrounded by public streets are like an archipelago of islands set in a sea of public space' ([2], p. 13). Thwaites et al. [21] address different aspects of urban spaces as a betweenness milieu, which mediates between private and public. Also, they sought to highlight the role of the community in making the urban decisions in order to draw at least the local scale or micro scale of their neighbourhoods. This contribution has been defined as the *Transitional Edge*.

According to Thwaites et al. ([21], p. 85), 'a public to private gradient that works in a continuum from private to public and vice versa… [it is] a smooth and complex gradient of subtle changes where a greater range of spaces allows greater diversity of intimacy and social interaction'. Jacobs identifies three main qualities required to successfully encourage people into the street: (1) the situation requires visible demarcation between private and public areas; (2) a particular level of surveillance regarding eyes upon the street and (3) users who exploit the street reasonably, continuously and as effective eyes, in turn, induce others in adjacent buildings into the street to watch not the sidewalk but the pedestrians [19].

Marshall [20] states that there are several subtle complications when understanding privacy; it is not only a single modest linear movement between public and private. Private (exclusive space) means operating the action, giving control of space to reserve a specific area for specific individuals or even a group, contributes to raising the overall supervision and shapes the pattern of difference between public and private. The public (inclusive space) infers to an area where people are able to move, meet, mix and interact [20] (**Figure 8**).

#### *3.1.1 Street edge characteristics*

The street is the artery of a city regardless of its classification; for example, the street form (straight, irregular or zigzag), street function (residential, commercial, mixed-use), street dimensions (its length and width), street class (main, secondary, connected street) and street type (open-ended, cul-de-sacs). One of the main aims of the street network is to enable people to access and move to/through the street network towards their destinations. The street is much more than an urban spatial element; it has a crucial space that is to manage the entire movement and people influx. Besides, the street can be 'regarded as a fundamental building- block of urban structure, where, the public street system forms the principal part of the urban transport system' ([2] a, p. 14–15). Hillier [22] states that good spaces are utilised spaces; in this respect, an urban area is utilised by the movement to and/or the through movement. Furthermore, the street proffers routes from everywhere to everywhere else, and its influence on movement is a fundamental source of the multifunctionality that promotes vitality in the city.

Marshall ([2], p. 15) states that 'the challenge is to address the street as an urban place as well as a movement channel, and how to make this connection of the street work – not just as an isolated architectural set piece, but as a contribution to wider urban structure – otherwise, streets are for people'. Thwaites et al. [21] refer to ten themes that characterise the street edge and provide valuable insight into the socio-spatial properties relevant to transitional edges. The ten themes are: 'social activity, social interaction, public-private gradient, hide and reveal, spatial expansion, enclosure, permeability, transparency, territoriality and looseness' ([21], p. 78–79). Hillier et al. [13] denote that the integration of core maps covers the main streets and shopping areas.

Shopping streets tend to become viable when they have a high level of retail that is integrated with the global network and local pedestrian movement.

#### *Sustainable Development Dimensions and Urban Agglomeration*

#### **Figure 8.**

*Street syntax: (a) all strategic roads connect to form a single network; (b) all private spaces connect to the single public space; (c) all buildings have an interface with the single outside space; (d) all buildings connect to the single ground surface. Source: Marshall [20].*

Less integration tends to occur in monofunctional areas, such as residential areas [13, 23]. The proportional place of the street and its integration within the entire network system play a crucial role in shaping the street edge characteristics. The configurational properties of the urban fabric are the primary influence on shaping two types of movement; through-movement and to-movement [13] (**Figure 9**). Movement and multiplier effects are significant prerequisites to promote the quality of street life. The multiplier effect attracts new development, new buildings and uses [22, 24].

*Transitional edge* is defined by Thwaites et al. [21] as the street edge and its multiple functions. It combines three dimensions: social, participatory and structural components. The *Transitional edge* encourages and diversifies the territorial experience to keep the community sustainably for those who use urban space efficiently. Therefore, this can be regarded as a spatial and sociological line. *Transitional edges* 'are coherent socio-spatial domains and not simply boundaries between the architecture and the external public realm …. offer the potential to achieve a more socially optimal balance of form, place and understanding [therefore] transitional

*The Street Edge: Micro-Morphological Analysis of the Street Characteristics of Baghdad, Iraq DOI: http://dx.doi.org/10.5772/intechopen.102403*

#### **Figure 9.**

*Two patterns depend on the spatial arrangement: Through-movement and to-movement. The first occurs with the layout as a system of possible paths; however, when the layout can be considered as a system of origins and destinations, then movement is a to-movement. Source: Drawn by the author based on Hillier's concepts.*

edges as key components in the socio-spatial order of the urban habitat' ([21], p. 23, 53, 71). Furthermore, Thwaites et al. [21] refer to another idiom of the street edge: the broken and unbroken edge that governs the degree of social interaction. It also conveys an impression of the extent to which people can interact with whatever broken or/and unbroken edges (**Figure 10**).

According to Jacobs ([19], p. 380) *Visual Street Interruption (VSI)* is when, 'a good many city streets (not all) need visual interruptions, cutting off the indefinite distant view and at the same time, visually heightening and celebrating intense street use by giving it a hint of enclosure and entity'. VSI encompasses a set of considerations when 'there is no visual tale of street intensity and detail to tell … and should be in functional terms, not dead ends but corners' therefore, 'visual street interruption is a natural eye-catcher, and its own character has much to do with the impressions made by the entire scene' ([19], p. 382–383). The street edge should be characterised by catching the eye and giving the space a rooted sense of place Buchanan [25]. According to Segall

#### **Figure 10.**

*Unbroken, an abrupt edge between architecture and the public realm with little hope of encouraging life (left). Abrupt edges are broken by doors and windows which begin to act as catalysts for social activity (right). Source: Thwaites et al. [21].*

#### **Figure 11.**

*The criteria of the street edge integration based on Carmona et al. [27]. Source: Drawn by the author.*

([26], p. 51, 73), 'the visual experiences most generally available in a particular environment predispose one to identify most readily material similar to the content of those experiences … the pattern of visual experiences in the lifetime of a person can modify his perceptions of objects in space' (**Figure 11**). Understanding the concept of *Visual Street Interruption* and its role in Baghdad could be a critical issue. Meaning that there is a delicate line between *Visual Street Interruption* and urban chaos in reading the street edge, the second phenomenon one could recognise in some urban areas of Baghdad city.

#### *3.1.2 Private edge characteristics*

Alexander [12] offers 253 patterns that are divided into 36 categories. One of these patterns is path shape, which is a crucial component in the built environment and contributes to other patterns in drawing the whole context of a city. Alexander([12], p. 590) advocates that the 'street should be for staying in, and not just for moving through, the way they are today'. Alexander ([12], p. 593) opposes the concept of setbacks, stating that 'buildings' setbacks from the street, originally invented to protect the public welfare by giving every building light and air, have actually helped to destroy the street as a social space … the setbacks do nothing valuable and almost always destroy the value of the open areas between the buildings' (**Figures 12** and **13**).

Marshall ([20], p. 105-112) states that the '… private plots and buildings… [where]… buildings and cities are different kinds of social container, reflecting their

**Figure 12.** *As the activities grow around the space, it becomes more lively. Source: Alexander [12].*

*The Street Edge: Micro-Morphological Analysis of the Street Characteristics of Baghdad, Iraq DOI: http://dx.doi.org/10.5772/intechopen.102403*

**Figure 13.**

*Four different intensities in four segments. Source: Thwaites et al. [21].*

differences in social structure. A city is not a big building, but is articulated into different buildings, mediated by a social fabric of public streets'. Additionally, one side of the street edge is subjected to private demands where the plots and buildings are located; this means that the facades are designed for private benefits [27, 28]. The expression of privacy ranges from soft control, like colour, texture and level, to hard control, such as fence and/or wall.

Furthermore, moveable and invariable can also classify the nature of privacy. Kostof [29] refers to the authority of using private space within the space of the street. He states that the buildings' edges need not be completely subjected to owners' desires, as there are public authority regulations that organise the street edge in such a way to increase the variety of building façades from block to block. The diversity works to impart the beauty of the block and street edge to the city; it incites attraction and surprise in people, whether inhabitants or visitors.

The *Filter Edge* is defined by Marshall [20] as a *social filter* when he states that the city is heterogeneous and involves different kinds of people who move through the social filter system. The systematic circulation of people ranges from loose filters, like streets, to reach fine filters, such as building edges. Therefore, he states that 'a building is an environmental container and filter; the building-plot-street system is both a social container and a social filter…. the importance of public streets as being not void, but as integral to the notion of a city, a kind of mortar binding between social units. Without this system of public spaces, a city would not be a city' ([20], p. 105, 112). Canter ([30], p. 9) argues that 'the environment providing perceptual stimuli [and] also be thought of as a filter … we are always in the environment to carry out certain activities, and we usually carry out these activities with other individuals … this is the fact that we actively modify, build and influence our physical surroundings'.

#### *3.1.3 Public edge characteristics*

The sense of public space is one of the main concerns and dialogue in generating social interaction and improvements in street life. The public edge embeds a broad

spectrum of events, activities and social assemblage. It is a place where people should feel free to express their aspirations and desires. It 'host[s] structured or communal activities—festivals, riots, celebrations, public executions—and because of that, such places will bear the designed evidence of our shared record of accomplishment and our ritual behavior' ([29], p. 124). Accordingly, 'the main public places of a city are its most vital organs [thereby] if a city's streets look interesting, the city looks interesting; if they look dull, the city looks dull' ([19], p. 29). Banerjee ([31], p. 14) suggests that 'the sense of loss associated with the perceived decline of public space assumes that effective public life is linked to a viable public realm. This is because the concept of public life is inseparable from the idea of a public sphere'.

The public edge forms the third domain for social interaction, and investment in the function of the street edge encourages people to collect. The variety in the function of the public edge promotes street life and maximises social interaction [32]. It is necessary for the humanisation of public urban space such that the activities taking place contribute to the continuous surveillance of the space [33]. Oldenburg [34] adopts '*Third Place*' as an expression of other places, apart from settled places and workplaces. The third place should conjoin people in a free and mixed way by presenting exceptional comfort which is important to public life. The third place is a sorting edge that filters interests, and that people admire or 'un-admire' when using such places.

The highest value of the third place lies in its potential to encourage the meeting of people from diverse classes, age groups and with varied interests. It is important for the third place to be accessible, easy to reach and comfortable both for regular frequenters and newcomers. Furthermore, *unplanned*, *unscheduled*, *unorganised* and *unstructured* are four characteristics of the third place, which define it as essential, universal and pivotal to informal participation and social interaction [34].

Hall [35] refers to two types of spaces; *Sociofugal* is a space that keeps people apart, and *Sociopetal* is a space that brings people together. Engwicht [14] states that 'a vibrant spontaneous public realm, therefore, allows greater flexibility in our private relationship' ([14], p. 27). However, motorised regulations and their requirements exploit the public realm and drive away from the realm of the spontaneous encounter, which forces people into what Sennett [36] called the '*polarization of intimacy*'. Jacobs [19] states that the spatial social theme within the public space should be employed to capture what she called *self-appointed public characters*.

**Figure 14.**

*Demonstrating the ability of different types of urban space to shape three street edges. Source: Drawn by the author.*

*The Street Edge: Micro-Morphological Analysis of the Street Characteristics of Baghdad, Iraq DOI: http://dx.doi.org/10.5772/intechopen.102403*

#### **Figure 15.**

*Illustrating the main characteristics of the street edge and the edge of its private and public domains (based on a considerable number of authors and scholars). Source: Drawn by the author.*

A public character is a person who frequently maintains contact with those who also use the same edge. Prosperous public places, according to Carmona et al. [27], are characterised by the frequent attendance of people in self-reinforcing ways. The public space is an optional and available environment, that people can choose whether to visit. Hillier [22] states that the street as a space for movement shapes the primary activity for those who prefer to stay or go.

*Self-control* can characterise public edge even though space is designed for public benefit. At the same time, it characterises private control by those who regularly use it. Zukin [37]suggests that there is not only social diversity but also the diversity of buildings and that helps to give a city its 'soul'. He mentions that, "the paradox of public space is that private control can make it more attractive, most of time, to a broader public, but state control can make it more repressive, more narrowly ideological, and not representative at all"([37], p. 158). Moreover, Jacobs [19] defined the 'eyes upon the street' where these eyes belong to people who contribute to shaping the property of the street [38–43] (**Figures 14** and **15**).

#### **4. Three edges' characteristics in referring to Baghdad City**

According to Hillier [22], in Arabic cities, diversity can be found in the development of the same underlying law. This tends to enable well-defined relationships between different levels of movement in the urban context. The old urban fabric seems quite complex in its street network, particularly within traditional Arabic cities; however, three domains play a crucial role in formulating the character of the street edge in such cities, namely street, private and public. Islamic cities are associated with what is called pre-Islamic regions, which inevitably have their own entities and identity regarding urban patterns, building typologies and construction techniques, besides, the natural and physical environment [44]. The ancient Mesopotamian model of clustered courtyard buildings, which date back to the 2500 B.C., provide evidence of the traditional settlement areas in other surrounding regions. Ur city is an ancient

#### **Figure 16.**

*Plan of a portion of the ancient Sumerian city of URas it was about 1900 B.C. (left). Plan of the city of Babylon at the height of its power, about 600 B.C. the religious features were dominant (right). Source: Lynch [45].*

town situated to the south of Mesopotamia where its construction pattern matches the Islamic traditional cities that emerged later (**Figure 16**) [44, 46].

*Urf* is a systematic generative process (relating to the concept of habit or custom in English). *It* is a hidden order grounded in the consciousness of a community without the need to be listed, where every single member of the society is aware of what *Urf* is. Its principles and influences formed a pattern within traditional Arab and Islamic cities over time. *Urf* is initially based on human behaviours and the acceptance and satisfaction of these among a community, which generates these behaviours; these are compatible and match with Islamic rules. Otherwise, such individuals are rejected by society. Repeating the action means it becomes a habit, 'for every act there must be an impetus or reason… therefore every *Urf* is a habit, but not every habit is *Urf*" ([47], p. 110). *Urf* has become a source of legislation: it is flexible, changeable and dynamic in simulating the reality of life and its conditions. Recently, the term *Urf* could be pretty limited in serving and formulating public and private space use criteria. Unfortunately, this phenomenon is quite evident in a significant number of neighbourhoods of Baghdad. This paper tends to highlight the idea of *Urf,* apart from going deeply in explaining this concept in terms of implication.

Three factors, identified by Hakim [44], affected the nature of Islamic traditional settlements regarding their building patterns and planning. These are: (1) Pre-Islamic urban models and their people, culture and civilisations in territories that converted to Islam, where the norms and customs have continued their influences on the Islamic culture hitherto. (2) A transport pattern was made by the two-primitive means (camel and horse), which affected the street network patterns and the urban fabric of traditional cities between the fourth and sixth centuries A.D. (3) The surrounding natural environment embraced most Islamic regions located between latitudes 10 and 40. Thus, the microclimate was shared with the same analogical conditions.

The emergence of the Arabic/Islamic city was based on three processes. Firstly, it renewed an existing city founded in old colonial areas to meet the prerequisite for a social life among those people at that time. Secondly, they were pre-planned or planned cities, which were designed and pre-planned in accordance with Islamic rules and authorities. Historical resources and archaeologists confirm that the first primary planned city in the Islamic era was the round city of Baghdad, which was

*The Street Edge: Micro-Morphological Analysis of the Street Characteristics of Baghdad, Iraq DOI: http://dx.doi.org/10.5772/intechopen.102403*

#### **Figure 17.**

*Baghdad-Iraq, the geometric 8thCentury ground plan, organised around the Caliph's palace, was a casualty of the city's success. By the 9thCentury the sprawling growth of a thriving community had obliterated the original autocratic diagram. Source: Kostof [49].*

situated to the east of the Islamic region [48, 49] (**Figure 17**). Thirdly, as a spontaneous model, it can be identified as 'the most enduring and pervasive, and today most of the older areas of capitals and major towns in Muslim world evolved out of this model' ([44], p. 88).

However, Hakim ([50], p. 84) states that 'an important observation is that when colonialism ended, it left a gap between past and present and also left technology which did not evolve out of the past and has affected architecture considerably and in many ways, colonialism turned into cultural and technological dependency'. Consequently, serious negligence occurred with the introduction of new regulations for city planning. These new demands considerably affected the whole system of the old urban fabric; it was designed on a human scale and their needs aside from the large-scale urban spaces.

#### **4.1 Street Edge's characteristics**

The three street space components (street, private and public) integrate with the other components to provide one entity. The essential urban components that constitute the main character of the old urban fabric are the clustered courtyard buildings, street networks and the hanging elements. Two predominant types of street networks are embedded within the old urban fabric. The first is the open-ended street, through which pedestrians publicly flow, and the second one the cul-de-sac, which is governed by inhabitants, is a private zone, and thus not normally permissible for other people to enter or to use this type of street [40, 50, 51] (**Figure 18**).

The old part of Baghdad is characterised by a maze of narrow streets continued, designed to meet the needs of pedestrians (**Figure 19**). The traditional pattern forms a more preferable sense of community, which appears serene and shadowed for the most significant part of *Zugag* during the day. Adjacent houses, *Zugag*, are varied in width; in some cases, these are no more than 3 m. While at the top, because of the *Shanashil* (prominent windows as a hanging or high-level protrusion) the street was almost covered over. The main *Zugags* in the residential quarters of the old part of Baghdad are usually found on mosques and bazaars. This feature can also be observed in Arab cities [51–53] (**Figure 19**).

The hanging element is a '*high-level protrusion*' that can easily be seen during peregrination throughout the old urban fabric; the component was constructed above the street. This element has a unique name in the traditional area of Baghdad city '*Shanshul* (the plural is *Shanashil*)' is an oriel window. It is an upper-floor projection of a courtyard house, varied in size and shape in terms of ornamentation and decoration, and juxtaposed against the mass and shadow of the adjacent street [53, 54]. *Bridging the* 

#### **Figure 18.**

*The contemporary aerial scenery from the traditional part of Baghdad, al-Karkh. It shows the street pattern, cul-de-sacs and open-ended. Source: Prepared by the author based on the georeferencing aerial imagery authorised by R.S.GIS.U [51].*

#### **Figure 19.**

*A magnifier slice of the traditional part of Baghdad city, Al-Rusafa. It displays the traditional street pattern; Zugagsand surrounding neighbourhoods (Mahallahs). Source: Drawn by the author based on the georeferencing aerial imagery authorised by the G.I.S. Department [52] and R.S.GIS.U [51].*

*street* denotes 'bridging the street, and the buttressing arches spanning between walls on either side of the street to provide structural strength and support' ([44], p. 89).

In traditional Islamic cities, a street refers to the central market. The street market on both sides is several repetitive small chambers that are opposite to each other and separated by about 10–20 feet. To enable pedestrian flow, the street is mostly covered by vaults that include skylights, which allow sunlight to pass through and

*The Street Edge: Micro-Morphological Analysis of the Street Characteristics of Baghdad, Iraq DOI: http://dx.doi.org/10.5772/intechopen.102403*

#### **Figure 20.**

*Safafeer Suq (market) is one of the oldest traditional market where copper plaques and plates are attached to the shops. This Suq was delegated for copper works, but has since been occupied by the textile merchants, thus minimising the number of artisans who work withthe copper products. Source: Photographed by author's team, 04/December/2016.*

protect the customers from undesirable climate conditions. Mostly, each street market is connected by the organic network of the narrow lanes or by other street markets. The other public facilities, such as mosques, baths, hotels or Khans are located close to shopping streets and thus, as an access network are maximally utilised ([44], p. 101, [55]). The traditional *Aswaq* (markets) are still alive in the old part of Baghdad, where each *Suq* is delegated for specific products and purposes, such as the Textile *Suq*, Book *Suq*, Copper *Suq*. The specialisation of functional uses is one of the leading characteristics in the old traditional markets, which are placed close to each other in a harmonic way (**Figure 20**).

#### **4.2 Private edge characteristics**

In Islamic cities, privacy is a central factor in determining the use of space; this includes direct visuals, particularly in residential areas. The cooperation between people and other institutions in formulating a generative system worked

#### **Figure 21.**

*Two Iraqi traditional courtyard house that illustrates the dogleg (broken) entrance that links the courtyard of the house and the street as a public space. Source: Reuther [58]. All right reserved for Al Warrak Publishing Ltd., London, UK.*

to maintain the rhythm and hierarchy between the private and public domains [56, 57]. Furthermore, the Muslim community tends to be more concerned with preserving privacy, not only from physical connections but also in terms of visual contact. The privacy factor significantly affects the morphology of the urban form in Islamic/Arabic cities and gives a distinct shape to the city. For example, the external street edge contains the main dogleg entrance that leads to the courtyard house [58] (**Figure 21**). The dogleg technique gives a high level of privacy for inhabitants where there is no direct access to the private space from the public realm. Despite the fact that entrances are on opposite sides and directly adjacent to the street, no entry directly faces another.

In the residential area of the old part of Baghdad, the lower level of the external wall that is adjacent to the street is almost blind and as solid as a windowless wall to the outside. To attract lighting and ventilation in the courtyard house, all rooms are oriented inwards to the courtyard. Therefore, the external façade lacks apertures except, occasionally, small niches beside the upper level that are designed with *Shanashil*. The *Zugag* exhibits simple façades with a minimum of details at the lower level; instead, rich detail and decoration is placed on the *Shanashil* and main entrance (**Figure 22**) [55].

Moreover, to avoid straight visual connections, people in traditional cities tend to adopt the overlooking technique in setting doors, windows, openings and heights, where 'in Islamic culture, protection from visual intrusion into the private realm of houses was the paramount consideration. Views were appreciated when available, but they took second place to the blocking of visual corridors into the private realm' ([59], p. 29). It allows for inhabitants to observe outdoor activities and pedestrian movement, but those who use the street were not able to see inside properties. This technique used the concept of *Shanshul*/*Shanashil* as the external element of the *Zugag* (local streets within traditional neighbourhoods) in the traditional area of Baghdad.

#### **Figure 22.**

*The traditional Baghdad Zugag where the street level tends to have a windowless and solid frontage (left). The main entrance of the courtyard house with the richness in decoration and detail (right). Source: Makiya [55]. All right reserved for Al Warrak Publishing Ltd., London, UK.*

*The Street Edge: Micro-Morphological Analysis of the Street Characteristics of Baghdad, Iraq DOI: http://dx.doi.org/10.5772/intechopen.102403*

#### **Figure 23.**

*Shanashil; as a serrated row of oriel windows. Source: Makiya [47]. All rights reserved for Al Warrak Publishing Ltd., London, UK.*

*Shanashil* were made up of smaller, modular, sash-window units; they are attractive architectural elements employed to promote the external edge of the *Zugag* (street). *Shanshul* includes wooden sliding windows and produces extra shadow for pedestrians against the direct sunlight, particularly in the summer season. Furthermore, the *Shanshul* technique traditionally plays a significant role in social interactions and allows inhabitants to conduct conversations through opposing rooms on the upper floor (**Figure 23**) [54].

The concept of *bridging the street* also has been observed in the traditional area of Baghdad but did not spread widely, like *Shanashil*. Technically, this type of highlevel protrusion belongs to one owner or exploits links between two properties that belong to the same inhabitant (**Figure 24**). In the non-residential property, they are employed for public use and have the same characteristics. Traditional shape complements the street pattern and the socio-physical structure of Baghdad, for instance, mosques and hammams. These types of buildings are oriented entirely towards the internal courtyard.

A street provides a distinction between the private and public space in the traditional area of Baghdad; it is very controlled and restricted regarding the degree of permeability, transparency, accessibility and connectivity. The street is almost

#### **Figure 24.**

*The concept of bridging the street in the traditional area of Baghdad, but it does not spread commonly like Shanashil. Source: Reuther [58]. All right reserved for Al Warrak Publishing Ltd., London, UK.*

solid on the ground floor and semi-closed or closed by *Shanashil* on the first floor. The house entrance and *Shanashil* form the only two channels to link between the private streets. In the modern context of Baghdad, within the residential area, the private edge varies from direct adjacency with the street to set backwards. The differences in street pattern, plot layout and block size, and the location of the building within the plot area play a key role in formulating the spatial organisation and provide distinct characteristics for each area of Baghdad (**Figure 25**).

The characteristic of the private edge in the modern pattern of the street network has different criteria and considerations. This leads to different interpretations of the private edge and the extent to which inhabitants have the authority to claim the juxtaposing space located in front of their property. It also influences the boundary of the street width, and to what extent it is for public use. The absence of a clear definition for the private, public and street edges, particularly in commercial streets which broke through the traditional area, has resulted in complicated situations and difficulties in how to manage this critical area of Baghdad (**Figure 26**).

#### **4.3 Public edge characteristics**

The public edge formulates the vitality of the street, where it enables people to interact either with the street edge or with other people. Tolerance depends on different criteria and rules, besides the norms of society (values and *Urf*). In the traditional area, the norms and *Urf* can be realised as concealed orders indoctrinated in the consciousness of society without the need for documentation. People realise the system of norms and *Urf* and then accordingly, shape their behaviour. The concept of *Urf* is related to the traditional area of Arabic/Islamic cities, where these types of areas were normally based on a set of treaties accepted by people.

The idea of *Al-Fina* can be addressed as one of the public edge's characteristics in the old traditional part of Arabic/Islamic cities, such as Baghdad. *Al-Fina* is a spatial element that distinguishes the street edge and interior courtyard of a house. *The Street Edge: Micro-Morphological Analysis of the Street Characteristics of Baghdad, Iraq DOI: http://dx.doi.org/10.5772/intechopen.102403*

#### **Figure 25.**

*The modern context of Baghdad within the residential area, the private edge manifests an important transformation which is adjacent with the street edge towards the back. The differences are apparent in street pattern, plot layout and block size, and the location of the building within plot area. Source: Prepared by the author based on the georeferencing aerial imagery authorised by R.S.GIS.U [51].*

#### **Figure 26.**

*The absence of a clear definition of the private, public and street edge, particularly in commercial streets that go through the traditional area, have resulted in complicated situations where sellers deliberately present their products within the street arcades. Al-Rasheed street. Source: Photographed by author's team, 21/ December/2016.*

It is located immediately adjacent to the peripheral exterior wall, opposite the street space. It serves daily and temporary uses without a need to own the space [60]. Moreover, the combination of zigzag and a string of narrow and wider areas along one street provides visible evidence of the design of a traditional city in the Islamic/ Arabic world (**Figures 27** and **28**).

#### **Figure 27.**

*al-Fina is one of the leading characteristics of traditional Arab/Islamic cities. It refers to different purposes which both private and public domains can benefit from, but it is never be owned by anyone. Source: Hakim [60].*

#### **Figure 28.**

*A street in the traditional part of Baghdad, Al-Karkh. Note the steps of the houses on the left of the picture, and verandahs on the upper level; both are located within the Al-Fina domain, besides having other hanging features. Even the car stop is subject to the same concept, despite the limitations of public edge. Source: Photographed by author's team, 05/December/2016.*

*Al-fina* is completely changed in the modern neighbourhoods, where the builtup area is placed with the frontage set back. However, the area adjacent to the front wall of their properties is still used by people for different purposes, meaning that the authority of *Al-Fina* has been adopted differently. It might be recognised as a type of soft territorial space, 'if territories are relatively small (garden or house versus park or apartment building, for example), and if they can be modified or maintained with modest effort, then it is easier for individuals or small groups to achieve control' ([45], p. 213) (**Figure 29**).

Furthermore, the concept of the '*in-between*' space is used by Nooraddin [18] to denote a transitional milieu that mediates between the street and private space often in Arabic/Islamic traditional cities. In fact, there are no hard barriers between the in-between space and the street. The in-between space is generated by the consumer of street space, 'In between phenomena, how it was organised

*The Street Edge: Micro-Morphological Analysis of the Street Characteristics of Baghdad, Iraq DOI: http://dx.doi.org/10.5772/intechopen.102403*

#### **Figure 29.**

*Two examples from modern neighbourhoods in Baghdad exhibits how people pretend to make territorial space at the front wall of their properties. Partially covered area (left). Entirely paved by the inhabitant and using a ramp to access to the house located outside the private edge (right). Source: Photographed by author's team, 12–13/December/2016.*

#### **Figure 30.**

*Left, reconstruction of the in-between spaces of a commercial street in traditional Islamic Arabic cities. Right, reconstruction of the in-between spaces of a residential street in traditional Islamic Arabic cities Nooraddin [18].*

in the old Islamic cities and how it contributed to the character of their street environments' ([18], p. 66). The in-between space is mainly located in the front of the private area where it is used as a gathering space and for different activities. This type of space has loose meaning that there is no specific shape to give it a final form. Instead, it is flexible in both investment and appearance. It enables people

**Figure 31.**

*Al-Mutanabbi as one of the more traditional vital streets in the heart of the old part of Baghdad. It is vivid in attracting a massive amount of people from different gender, ages and for various purposes. It is the main resource for books, publishing, stationery, and knowledge exchange. Source: Photographed by author's team, 21/ December/2016–202106/January/2017.*

to meet their needs and desires as much as possible regarding comfortable climate, religion, lifestyle, community and cultural aspects. Two types of in-between space are defined as: (1) related to the commercial street, and (2) located on the residential street (**Figures 30** and **31**) [18].

According to Hall [35], the in-between space shapes the microcultural theme, where it attracts the people to share the same territorial area. This notion, to a large extent, is rooted in the old part of cities. Hall [35] distinguishes three types of proximate behaviours that manifest in a space – *Infracultural*: behaviour rooted in the human biological past, *Precultural*: the physiological level in the present, *Microcultural*: based on which most proxemic observations achieve. The *Microcultural* pattern encompasses three aspects (buildings, space and the distances maintained in encounters with others) which define territorial patterns, '… in every sense of the word an extension of the organism, which is marked by visual, vocal, and olfactory signs. Man has created material extensions of territoriality as well as visible and invisible territorial markers ([35], p. 103).

Can and Heath [17] use the term *In-between* to study social interaction and the morphological form of a city. They examine spatial configurations that occur in different street patterns: traditionally and modern. In traditional Islamic and Arabic cities, the *In-between* space reflects a social interaction between neighbours where it offers a niche within the street edge and in turn, improves the street life. The pockets of activity play a significant role in shaping a live space; it mediates activities and the path as an in-between area in order to create an attractive space for people to pause and get involved [12].

Kostof [29] states that public spaces are defined by residual, interstitial spaces located between neighbourhoods' cells, such as bazaars or *Aswaq* and *Maidans* (public squares). The contrast with Western urbanism lies in the fact that it pays more attention to the street system and public spaces. The urbanism process in traditional Arabic/Islamic cities is based on the inside to outside, and is understood as a bottom-up approach, or, in other words, from private tendencies to public propensities. In Arabic/Islamic cities, the sense of public space is defined in soft boundaries rather than hard borders, where the users and visitors share the same norms and values by investing in the public spaces. Kostof ([29], p. 127) states that 'regardless of the private use of these resources, they could never be privately owned. Every member of society had equal claim to public places, be Muslim or

*The Street Edge: Micro-Morphological Analysis of the Street Characteristics of Baghdad, Iraq DOI: http://dx.doi.org/10.5772/intechopen.102403*

#### **Figure 32.**

*Two symmetric scale of street patterns in Baghdad (left: Case A) and (right: Case D) show the dramatic transformation in the concept of Suq (Aswaq), from organic theme to loop-grid where the movement is changed from the spontaneous streamlined to a planned change direction. Source: Drawn by the author based on the georeferencing aerial imagery authorised by the G.I.S. Department [52] and R.S.GIS.U [51].*

non-Muslim. Whoever comes earliest to a public place has the right to make use of it through that day'. The *Suq* (the Arabic plural is *Aswaq*), in traditional areas of Baghdad, derives from the organic street pattern as there is no dramatic change between the *Suq* space and other networks, but rather movement is spontaneous and streamlined. The transformation is not based on the morphology of the space and its distinct characteristics, but also on the functional pattern of the street. This, in turn, results in a new vista with each movement (**Figure 32**).

A *Suq* is a crucial morphological urban element that is spontaneously subjected to the hierarchy of location. *Aswaq* were organised in different ways, whilst the linear *Suq* functions as a continuum spatial route, where both its sides have opposite shops. As an area, the *Suq* denotes a series of back-to-back rows that are situated to face each other, whilst the units of a *Suq* are located against the perimeter of buildings [61, 62] (**Figure 33**). The pattern of a *Suq* and its spatial configuration came to exist as an assortment of different types of *Aswaq* (Arabic plural). It had various functions in order to serve a significantly sized community within the same scope, where *Aswaq* were located to be proximate and adjacent to each other. The proximate pattern of

#### **Figure 33.**

*Spatial configuration of Suq pattern in the traditional area of Baghdad; Al-Safafeer Suq (left) and Al-Mutanabbi Street (right). Source: Photographed by author's team, 04/December/2016–21/December/2016.*

#### **Figure 34.**

*Sample of the pattern of a Suq with its spatial configuration came into existence as an assortment of different types of Aswaq. This aimed to provide various functions in order to serve a significant amount of the community within the same area. They were located near and/or next to each other. Source: Drawn by the author based on the georeferencing aerial imagery authorised by the G.I.S. Department [52] and R.S.GIS.U [51].*

distribution of *Aswaq* provides a distinct morphological form in the traditional area of Baghdad. The proximity enables people to combine shopping and viewing the sights (**Figure 34**).

Functional proximity is often one of the important criteria for the closeness of the *Aswaq*, for example, *Al-Mutanabbi* street is designated for bookshops, publishing and stationery storage; moreover, it is close to *Al-Sarai Suq* to provide stationery and books (**Figure 34**). Along with the value of proximity, the pattern of the street in this part is more complicated and based on the organic network, which developed spontaneously. The proximity governs the location of the *Aswaq* and the other social facilities, such as the *Masjid* (mosques), *Gahwah* (café), *Hammam* (public bath) and *Sahaht* (squares), where people are able to access different activities. This sense of proximity, to a large extent, is lost in some modern neighbourhoods in Baghdad, with their new street patterns that were established according to carbased movements. This resulted in minimal social interaction, and it maximised the distance between settled units and the *Aswaq*, besides other facilities and services (**Figures 32** and **34**) [63, 64].

Proximity, in this regard, is based on human demands, regarding accessibility and connectivity. This considers '*where*' as the settled units in which people live,

*The Street Edge: Micro-Morphological Analysis of the Street Characteristics of Baghdad, Iraq DOI: http://dx.doi.org/10.5772/intechopen.102403*

#### **Figure 35.**

*Al-Sahah (Sahaht–as plural), Baghdad, al-Karkh (case B -left). It emerges spontaneously and is embedded in the urban fabric and customarily located where two or more streets come together to form a connective space. Case D (right) is a new modern pattern which exhibits fragmented squares as superfluous. Source: Drawn by the author based on the georeferencing aerial imagery authorised by the G.I.S. Department [52] and R.S.GIS.U [57].*

and '*there*' where their needs are located. The traditional part of Baghdad, like other Arabic/Islamic cities, emerged initially from a bottom-up strategy, where the community had the authority to shape and reshape the built environment so that it harmonised with their needs [56, 65]. In the traditional area of Baghdad, Al-Ashab [53] refers to another morphological element that characterises the urban context of the street pattern in this area, namely, *Al-Sahah* (*Sahaht* – as plural). It emerged spontaneously within the urban fabric and is normally placed where two or more streets come together to shape the space of connection. This space has been used as a meeting place for neighbours. *Sahah* within *Mahallahs* (neighbourhoods) were full of life and attractive as social interaction spots that eventually spread through the traditional urban fabric [53].

*Sahah* space refers to several *Sahaht* that are varied regarding the size; it ranged from the more private space, such as the courtyards of traditional houses, tertiary *Sahah*, and more public areas like sub-*Mahallah* or secondary *Sahah* and the primary *Sahah*. The hierarchy of accessibility from small to the large *Sahah* was perceived both by those who lived there as well as visitors (**Figure 35**) [53]. In a new urban context, where the squares (*Sahaht*) develop from a planned process, open spaces are meaningless and void from any common function. They, however, enable the unnecessary physical expansion of the city, and the sense of human scale is lost as their geometrical dimensions are not subjected to other surrounding urban elements; thus, the enclosure is also missing. In the modern pattern, squares fall out of the authority of inhabitants, as there is no explicit declaration about the claim for this type of area. Moreover, there is a deficiency in determining the nature of use, even though they are designed for public use (**Figure 35**).

#### **5. Conclusion**

Defining the street edge was the primary aim of this paper in order to highlight the different interpretations and meanings of the three fundamental elements that function together to formulate the street. These elements are the street, the private edge and the public edge. The transformation in the urban structure from the

traditional pattern to the modern model not only changes the morphological dimension but also influenced the relationship between the private and public realm. The manipulation of private and public relations could be the primary condition to figure out the street life and how people interact with each other. Hence, different variables could be employed to measure the relationship between the private realm and the street space at a micro-level. These factors are experienced by those who use a street when dealing with the street scope within a specific segment. The permeability, inter-visibility, connectivity and accessibility are different between the traditional area and the modern parts.

The notion of the private-public was examined to investigate the street's edges. Each realm was addressed in detail by emphasising the basic morphological process based on the edge's characteristics. The critical interrelationship between two edges: private and public represents the micro-level of a street segment that is used to evaluate the interrelationship and how could affect street life and social interactions along the street edge. Across the traditional pattern and modern model of the neighbourhood, there was a significant disparity between the private and public edge.

People have a set of expectations when they determine their interactions with individual action or collective behaviour in a particular street edge. Classifying the street space into three edges is an essential method in order to understand human behaviour thoroughly and how could people respond to each other and the three edges: street, private and public. Fine-scale is another aspect to address the physical environment at the street scale; also, the micro-level could be one of the strategies to deal with the street parameters in terms of the ability of the different edges in managing human behaviour. Indeed, there is a need to distinguish between two patterns; the first one is based on the bottom-up approach as a spontaneous pattern, and the second is the up-down method as a pre-planned model. Once understand the differentiation of traditional area (spontaneous) and new neighbourhood (pre-planned), it would be there a thoughtful procedure to deal with the private and public edge.

There is a lack of required building legislation and maintenance monitor programs for planning and urban design, including a lack of commitment to restrict initiatives to assure they conform to traditional patterns. Therefore, addressing the central gap means verifying the most critical indicators of the street edge problem, both in traditional and modern patterns, which necessitates the detection of related studies that try to link the urban form with active-ties and human behaviour alike. The traditional region emerged spontaneously apart from the notion of land use or zoning diagram. This characteristic is a crucial point within urban development schemes. The street pattern and paradigm of the buildings in the area are intricate; accordingly, there is a need to develop particular standards and regulations to preserve the identity of old Baghdad and understand the contemporary objectives of the new pattern. In this regard, proffering more further consideration to the centre of Baghdad is required, meaning that the control of this traditional region ought to be studied and systematic to advanced quality of life and to improve urban sustainability.

Terminologically, urban symbiosis could be aligned with sustainability, but this term can cover what is related to human behaviour and street activity. The main aim of symbiosis is to create a high interaction productive relationship between creatures. The notion of symbiosis holds three kinds: Commensalism, Parasitism and Mutualism. To comprehend the fundamental system in the traditional pattern of Baghdad city, understanding the micro-level of activity and fine-scale of the urban fabric is required to form a symbiotic platform. Including the processing of the morphology and the relationship between the plot, block and street network, also the symbiotic relationship between the public and private domains. European experiences in dealing with outdoor activities and how people respond to the street

#### *The Street Edge: Micro-Morphological Analysis of the Street Characteristics of Baghdad, Iraq DOI: http://dx.doi.org/10.5772/intechopen.102403*

edge have been highlighted thoroughly by different scholars and significant studies. People effectively experience this urban knowledge and urban life at the micro-level of the street edge in participating in the fine characteristics of such edge. In this respect, Jan Gehl's school could be one of the more significant experiences in dealing with street life.

### **Acknowledgements**

I would like to express my gratitude for the thoughtful guidance from my supervisor Professor Sergio Porta, from the Urban Design and Director of UDSU at the Urban Design Studies Unit, Department of Architecture, University of Strathclyde, sergio.porta@strath.ac.uk

#### **Author details**

Haider Jasim Essa Al-Saaidy Department of Architectural Engineering, University of Technology, Iraq

\*Address all correspondence to: haider.j.essa@uotechnology.edu.iq

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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#### **Chapter 12**

## Models and Strategies for the Regeneration of Residential Buildings and Outdoor Public Spaces in Distressed Urban Areas: A Case Study Review

*Alessandra Battisti, Livia Calcagni and Alberto Calenzo*

### **Abstract**

Given three-quarters of the European population living in urban areas, cities are expected to deliver sustainable growth if they will be able to further thrive and grow, while improving resource use and reducing pollution and poverty, as highlighted also by Sustainable Development Goal 11. In the context of vulnerable and marginal areas within cities, which suffer from multiple deprivations, regeneration processes at the building and district-scale play the most significant role in making cities more inclusive, sustainable and resilient. Reuse and refurbishment strategies, measured building replacement and stratification, redevelopment and enhancement, nature-based solutions and bioclimatic technological devices, are all tools for an integrated regeneration process capable of stimulating the urban metabolism and act as a driving force for the self-regeneration of the city. A comparison of two different building typologies, brought about by a review of existing public housing case studies in the outskirts of Rome, Italy, allowed us to define efficient, sustainable strategies and guidelines, that can be adapted to similar contexts in terms of building typology, social and economic conditions and of relationship to the rest of the city.

**Keywords:** urban regeneration, distressed urban area, sustainable technologies, public housing, energetic retrofitting

#### **1. Introduction**

The 2030 Agenda adopted by the United Nations General Assembly in 2015 and defined by the subscribing members as "a plan of action for people, planet and prosperity" has identified 17 goals in order "to take the bold and transformative steps which are urgently needed to shift the world onto a sustainable and resilient path" [1]. The goals refer to different fields of social and economic development and must be addressed through an integrated approach, aimed at achieving sustainable progress. The United Nations Inter Agency Expert Group on SDGs (UN-IAEG-SDGs) has developed 169 global targets, and 234 indicators that have to be monitored—as a global reference framework—in the period 2015–2030. In particular, Goal 11 deals

with the urban sustainability issue and emphasizes how cities play an essential role in achieving the Sustainable Development Goals since half of the world population and three-quarters of the European population live in urban areas. All over the world, cities are responsible for the largest share of energy consumption and carbon emissions, for the growing pressure on the environment and the related public health issues [2].1 The governance of urban space, therefore, represents a crucial development factor capable of posing worldwide challenges and opportunities. Several aspects must be considered in a systemic, inclusive and integrated way to ensure that cities thrive in a sustainably. It is vital to ensure that the population living, working or passing through the city has access to mobility, quality housing and safe conditions, both in terms of structural stability of public and private buildings and infrastructures, and protection from crime, violence and harassment.

Moreover, the presence of green spaces and public spaces, the protection of the cultural and natural heritage, the redevelopment of run-down areas, the relationship between the city and peri-urban and rural areas are as crucial as the aspects mentioned before. Yet, to be able to proceed in this direction it is essential to work according to an integrated approach that addresses the physical and structural aspects of the city, as well as the intangible ones. These last ones range from social and cultural aspects to those related to work and local economies, within broader processes that activate latent or already existing projects and social energies, which very often require policies from below. This process has already been triggered with the 2007 Leipzig Charter together with the related integrated urban development strategies that at a national, regional and local level focused on the cultural and architectural qualities of cities, conceived as strong tools for social inclusion and economic development useful to positively affect economic prosperity, social balance and the environment, within a coordinated process between spatial, sectorial and temporal aspects of urban areas. This process continued with the Toledo Declaration of 2010, which suggested a transversal, multidimensional and holistic design approach to achieve multiplying, complementary and synergistic effects, solving conflicts and finding the right balance between temporal (short, medium, long term) and spatial (region, metropolitan area, city, neighborhood) needs. These recommendations are reiterated and strengthened in the newborn Renovation Wave strategy, part of the European Green Deal promoted by Brussels which places the redevelopment of the building stock in a relevant position as an essential measure for decarbonization and reduction of emissions and as a tool for boosting the economy and European competitiveness. The new Renovation Wave strategy aims to double the urban regeneration rate, currently at 1%. According to Brussels estimates, a significant share of 35 million renovated and regenerated buildings could be reached by the end of the decade [3]. This situation would lead not only to significant ecological and energy benefits, but also to social ones considering that a recent report on sustainable recovery asserts that building renovation offers the greatest employment leverage: 12–18 local jobs for every million investments. This potential would create by 2030 as many as 160,000 new jobs in the EU construction sector [4].

More specifically, the Renovation Wave strategy will prioritize action in three areas: decarbonization of heating and cooling; tackling energy poverty and energy inefficiency; renovation of public buildings (schools, hospitals and offices). It will do so through several measures that make energy redevelopment operations easier

<sup>1</sup> There are various estimations of urban consumption of energy and related emissions. According to the World Energy Outlook (November 2008) http://www.worldenergyoutlook.org/index.asp, much of the world's energy is consumed in cities. Cities today house around half of the world's population but account for two-thirds of global energy use. Because of their larger consumption of fossil fuels, cities emit 76% of the world's energy-related CO2).

*Models and Strategies for the Regeneration of Residential Buildings and Outdoor Public Spaces… DOI: http://dx.doi.org/10.5772/intechopen.102366*

and faster.2 "The green recovery starts from home," said Energy Commissioner Kadri Simson, "with this initiative we will face the numerous obstacles that today make the restructuring complex, expensive and slow, slowing down many necessary interventions" [5].

Furthermore, the recent COVID-19 emergency sets before us a new vision of residential heritage, having highlighted its limits—in particular those of the public residential heritage. Therefore, urban regeneration offers the opportunity to rethink housing models. Today, more than ever, the challenges posed by epidemiological and climate changes bring to light more intangible realities which are more oriented towards generative social action. These realities require the involvement of actors, not only of the construction sector but also of the local community through the implementation of complex and long-lasting social projects, which must be designed to support first of all the most vulnerable groups.

#### **2. Italian intervention policies**

In Italy, the evolution of the concept of urban regeneration can be re-read within the relevant legislation, that marks the transition from the concept of recovery to the concept of rehabilitation, within the legislation presented and approved in the period

<sup>2</sup> The EU must adopt an encompassing and integrated strategy involving a wide range of sectors and actors based on the following key principles:—'Energy efficiency first'8 as a horizontal guiding principle of European climate and energy governance and beyond, as outlined in the European Green Deal9 and the EU strategy on Energy System Integration10, to make sure we only produce the energy we really need; − Affordability, making energy-performing and sustainable buildings widely available, in particular for medium and lower-income households and vulnerable people and areas; − Decarbonization and integration of renewables11 . Building renovation should speed up the integration of renewables in particular from local sources, and promote broader use of waste heat. It should integrate energy systems at local and regional levels helping to decarbonize transport as well as heating and cooling; − Life-cycle thinking and circularity. Minimizing the footprint of buildings requires resource efficiency and circularity combined with turning parts of the construction sector into a carbon sink, for example, through the promotion of green infrastructure and the use of organic building materials that can store carbon, such as sustainably-sourced wood; − High health and environmental standards. Ensuring high air quality, good water management, disaster prevention and protection against climate-related hazards12, removal of and protection against harmful substances such as asbestos and radon, fire and seismic 8 See Article 2(18) Governance Regulation (EU) 2018/1999: "'energy efficiency first' means taking utmost account in energy planning, and in policy and investment decisions, of alternative cost-efficient energy efficiency measures to make energy demand and energy supply more efficient, in particular by means of cost-effective end-use energy savings, demand response initiatives and more efficient conversion, transmission and distribution of energy, whilst still achieving the objectives of those decisions". 9 The European Green Deal, COM(2019) 640 final. 10 Powering a climate-neutral economy: An EU Strategy for Energy System Integration, COM(2020) 299 final. 11 This refers to energy from renewable sources produced on-site or nearby. 12 Climate resilient buildings mean that the buildings are renovated to be resilient against acute and chronic climate-related hazards relating to temperature, wind, water and solid mass, as appropriate. A complete list of such hazards is included in Table 1 of Annex I of Commission Implementing Regulation (EU) 2020/1208. 4 safety. Furthermore, accessibility should be ensured to achieve equal access for Europe's population, including persons with disabilities and senior citizens— Tackling the twin challenges of the green and digital transitions together. Smart buildings can enable efficient production and use of renewables at the house, district or city level. Combined with smart energy distribution systems, they will enable highly efficient and zero-emission buildings.—Respect for esthetics and architectural quality. 13 Renovation must respect design, craftsmanship, heritage and public space conservation principles.

between the 90's and the early 2000s. Indeed, national legislation moves from integrated intervention programs to urban redevelopment programs (L. 179/1992); from urban recovery programs (L. 493/1993) to district contracts (D.M. n. 1071–1072, del 1° dicembre 1994); from urban regeneration and sustainable development programs (D.M. dell'8 ottobre 1998) to urban rehabilitation programs (L. 166/2002).

It is precisely the building and urban rehabilitation programs (L. 166/2002) that introduce, alongside the concept of transformation of physical space, that of performance, especially linked to the concept of efficiency, taking into consideration also economic and social issues, including physical deterioration. In 2015, all these experiences led to the *Piano nazionale per la riqualificazione sociale e culturale delle aree urbane degradate* (national plan for the social and cultural redevelopment of deteriorated urban areas), where the concept of rehabilitation gained, within the concept of redevelopment, the meaning of quality not only of the physical heritage, but also of the intangible one. Still, in Italy, the concept of urban regeneration has been introduced only in recent decades, addressed by national and local policies (regional legislation) as a matter of territorial governance ascribed to the concurrent jurisdiction of States and Regions. In these policies, a strategic vision from above based on urban planning and programming comes along with a bottom-up regeneration process of common goods which starts directly from the citizens. Within the 2007–2013 programming of structural funds, which conceived intervening on cities as one of the priority actions, the term urban regeneration was reinterpreted as an integrated approach to urban development, capable of overcoming the fragmentation and sectoral nature of interventions in this field. This approach has found further confirmation in the 2014–2020 fund programming. The urban regeneration issue can also be found related to the measures on land consumption and on reuse of built land, where the term is intended, above all, as the recovery of the existing building heritage (DDL. C.2039 "Containment of land consumption and reuse of land built "approved by the Chamber on May 12, 2016). In the Code of public contracts (D.Lgs. 50 del 2016) instead, we find the concept of urban regeneration combined with horizontal subsidiarity interventions (art. 189) and administrative bartering (art. 190), where social partnership contracts are introduced based on projects proposed by an individual or associated citizens.

In recent years, several regional regulations in the field of urban planning and construction have been introduced within the framework of urban regeneration with a strategic vision of territorial planning, implemented through complex plans and programs. Many regional regulations reveal that the regulatory concept of urban regeneration differs more and more from that of building recovery and urban planning, and is gradually including complex actions for the urban, environmental and social rehabilitation of degraded urban areas. Examples are the regional law of Emilia-Romagna (L.R. n.24, 21 dicembre 2017) on the protection and use of the territory, the regional law of Tuscany (L.R. n.65, 10 novembre 2014), which lays down rules for the government of the territory, the regional law of Lazio, (L.R. n.7, 18 luglio 2017) containing regulations for urban regeneration and building recovery, just to name a few.

The law L. n. 158 dell'8 ottobre 2017—containing measures for the support and enhancement of small municipalities, as well as regulations for the redevelopment and recovery of their historic centers—complies with the goals mentioned above, where the concept of regeneration takes on a connotation of territorial and environmental protection and where small municipalities are recognized as a resource due to their role as a territory presidium, especially about their role in contrasting hydrogeological instability and in preserving and protecting common goods.

Urban regeneration, which is gaining an important space in regional legislation, still struggles to find a precise definition in the national one, where it is addressed

*Models and Strategies for the Regeneration of Residential Buildings and Outdoor Public Spaces… DOI: http://dx.doi.org/10.5772/intechopen.102366*

as an emergency measure by the D.L. 18 Aprile 2019, n. 32—" *Disposizioni urgenti per il rilancio del settore dei contratti pubblici, per l'accelerazione degli interventi infrastrutturali, di rigenerazione urbana e di ricostruzione a seguito di eventi sismici*" (urgent regulations for the relaunch of the public contract sector, for the acceleration of infrastructural interventions, urban regeneration and reconstruction following seismic events). The decree fosters the reduction of land consumption in favor of regenerating the existing building heritage by encouraging the redevelopment of degraded urban areas. Eventually, the unified text of the D.D.L. on urban regeneration, which is now under discussion, provides a state fund of 500 million euros per year until 2040 to co-finance regional tenders for the urban regeneration plans presented by the municipalities, thanks to an alliance between state, regions, municipalities and private individuals.3

#### **3. Sustainable urban regeneration**

In this context marked by a European policy strongly focused on energy saving and consumption reduction, the existing building stock and its redevelopment play an important role, especially the energy requalification of public housing (ERP) [6]. By public housing we refer to the residential real estate built, directly or indirectly, by the State, to be assigned, at particularly good economic conditions, to citizens with low incomes or who find themselves in poor economic conditions. The law regulating public housing identified three areas of intervention onto which allocate the available economic resources: subsidized housing of exclusive public ownership, assisted housing in property and/or with controlled rent and housing with agreements on surface or property rights. The fact that the European public housing heritage is plentiful and assorted, is a clear expression of the cultural and economic differences of our continent. In Europe, a significant share of the housing stock was built in response to the demand for housing following the Second World War. To date, more than 220 million buildings, representing 85% of the European building stock, were built before 2001. The majority of them are not energy efficient, as a result of old technologies and bad insulation—and account for around 40% of total European energy consumption and 36% of greenhouse gas emissions [3]. The physical (technical-functional), social and economic conditions of degradation that characterize the public building heritage demand the identification of immediate intervention strategies. The aim of the research is to show how certain strategies, in particular bioclimatic, modular and low-cost ones applied to the small building scale, can become the main tools for rehabilitating relevant parts of the contemporary city. For this reason, the research work described in this essay aims to give back urban quality to the suburban fabric which hosts public residential buildings through an architectural, energetic, bioclimatic and environmental requalification. This operation provides an attempt to read the peripheral palimpsest, through punctual and diversified interventions involving the description of the physical space, of the biophysical one and the understanding of bioclimatic phenomena, which cannot be separated from the understanding of the social space. Throughout

<sup>3</sup> Moreover, the text of the law provides also for the creation of a "database on reuse" of vacant and abandoned properties, for the right for Municipalities and Regions to raise taxes on unused or unfinished real estate units for over 5 years and for the possibility to resort to two-level design competitions. Finally, it provides for wide use of tax incentives (such as the superbonus, the eco-bonus or sismabonus) and for the establishment of a control room for urban regeneration meant to coordinate the interventions on different levels and to implement the national program goals, planned to be adopted within 4 months from the entry into force of the DDL.

the research, the role of the architect has been reconsidered as a social role that requires the ability to listen, interpret and explore the peripheral space, with the intent of setting shared and experimental assumptions to which reference can be made to overcome with the method and analytical scientificity the contradictions and conflicts of extended urban peripheries. Every overall transformation program, each detailed project is declined in this sense by associating several reinterpretations of the space and considerations on the possible scenarios of transformation, to develop, through a critical synthesis, an innovative conception of urban peripheral environment. This environment is meant to dialog with the consolidated city and to connect the redevelopment process to the cultural, social and technological transformations that affect society and urban form and that emphasize the need for new ideas, innovative models and relevant examples.

Overall, the analyses and evaluations of this research work start from the identification of the problems within the analytical phase and then explore the feasibility of intervention scenarios that can help to achieve greater urban quality. At the heart of the work, there are three research survey directions concerning:


Given the first research direction, the operational strategic lines address:


Regarding the implementation of the second research axis, the following operational strategic lines have been identified:


*Models and Strategies for the Regeneration of Residential Buildings and Outdoor Public Spaces… DOI: http://dx.doi.org/10.5772/intechopen.102366*

4.to optimize local hydrogeological conditions, considering rainwater runoff;


Finally, the third research axis aims at:


#### **4. Sustainable technologies, hypotheses and solutions for two case studies in Rome, Italy**

The case studies illustrated in the essay focus on the analysis and regeneration of two types of ERP multi-storey buildings, *in linea* (linear) and *a torre* (tower) blocks located in two different peripheral areas of the city of Rome.

The two-building typologies are taken into consideration using their similarities from an administrative and legal point of view and of their differences on a typological and environmental level and about their relationship with the context (**Figure 1**). The case studies analyzed are chosen to be representative of the respective building typology which recur in the ERP Roman context. The choice to study buildings located in peripheral areas is linked to the desire of investigating distressed urban areas [7], areas where it is even more urgent and necessary to intervene and where regeneration processes have a reorganization potential that transcends the architectural level and bring along positive effects on the socioeconomic conditions of the inhabitants.

Specifically for the tower high rise building typology, an ERP condominium was identified—part of a plot of four twin condominiums—in the north-western suburbs of Rome, XIII–XIV municipality, while for the linear multi-storey building typology an ERP condominium was identified—which is repeated 18 times with different orientations according to *Piano di zona 02v*—in the north-eastern outskirts of Rome, IV municipality. Both buildings were designed in the late 70s and built in the 80s in distressed urban areas of the city that differ in density (150 inhabitants/ha in Torrevecchia and 98 inhabitants/ha in San Basilio), in the degree of marginality compared to the adjacent context and the rest of the city as well as in the plano-volumetric system.

#### **Figure 1.**

*Territorial framework: two ERP case studies in Rome.*

The methodology adopted in this research allows, once the different hypotheses have been identified, to evaluate both the technical (energy savings that would result) and economic feasibility, as well as to verify the overall compliance with national and local regulations.

The methodological approach followed for both case studies provides for an analysis of the context and the current situation of the buildings starting from a territorial and urban framework with a specific focus on mobility, facilities and greenery. Subsequently, demographic, socio-economic and housing demand surveys were carried out. Ultimately, an environmental and micro-climatic analysis both of the entire context and the building under examination was carried out and finally, the architectural and technological components underwent a thorough examination. The aim is to detect critical issues at the building and housing level and to subsequently define the typological and functional program and the overall intervention strategies in line with technological and environmental requirements. The definition of the general morphological-functional characteristics of the intervention about the interaction model between microclimatic factors and the context led to the preliminary design. This initial design stage was developed according to studies and technical validations set at a meta-design level, followed by a functional study and the reinterpretation of housing schemes and supplementary facilities, according to the social demand. At last, a summary report on the identified demand/performance system was drafted: clarification of the environmental technological requirement system and its related design choices. The different strategies and design solutions underwent a definitive design elaboration of the building system and its subsystems and components in line with the environmental context and their interrelations with the transformations induced by the intervention.

#### **5. Tower high rise building typology in Torrevecchia, Rome**

The Torrevecchia district (**Figure 2**), built with funding from law L. n. 584 of 1977, is an area of approximately 24 ha with 1074 accommodations for 3600 inhabitants located in the north-west area of Rome in the Primavalle district, XIII–XIV

*Models and Strategies for the Regeneration of Residential Buildings and Outdoor Public Spaces… DOI: http://dx.doi.org/10.5772/intechopen.102366*

#### **Figure 2.**

*Aerial view of Torrevecchia district (source: Google Earth).*

municipality. It is owned and managed by the autonomous institute of popular housing (IACP), a specific Italian institution to promote, build and managing public housing to assign to citizens on low income rented at controlled rates. The architects P. Barucci, L. Passarelli and M. Vittorini were in charge of its design and execution. Until the 1960s Torrevecchia was part of the *agro romano,* and during the 1970s the area was affected by strong urbanization. The district is defined to the south by via di Boccea, to the west by via di Casal del Marmo, to the east by via Mattia Battistini and to the north by via Trionfale.

The plano-volumetric scheme is developed around a central square defined by four 15-storey high tower buildings (76 apartments) on which a group of offices and a bar overlook. Long 4/5 storey buildings (192 apartments) branch off from the central square with three levels of housing and a ground floor meant for shops, which were never realized.

Thanks to a progressive series of shifts, these volumes tend to spread out towards the extremity of the area thus creating in-between them two green spaces large enough to host respectively a small public park and a sports field. Car parking spots are located on the external side of the linear storey buildings, thus remaining outside of the central green areas defined by the building volumes.

Overall, the architectural solutions adopted in the different buildings are rather simple and they all respond to the constraints set by the standards imposed by law and by the economic means: prefabricated concrete panels and ribbon windows with metal frames.

#### **5.1 Analysis**

The IACP complex is commonly known as the "Bronx" due to its architectural aspect (poor architectural-spatial, environmental and energy quality of the buildings) and the socio-economic conditions of the area. The complex is strongly marked by economic precariousness, by the absence of public spaces and areas for meeting and socializing, by the absence of life and services at ground zero, and eventually by lack of maintenance and building degradation.

According to 2011 ISTAT census data (the Italian National Institute of Statistics, which is the main producer of official statistics in Italy), one out of four residents appear to be unemployed and 9 out of 10 people have reached a level of education

#### *Sustainable Development Dimensions and Urban Agglomeration*

below the middle school. The social hardship index, which provides a measure of the possible social-occupational drawbacks, is among the highest in Rome.

An analysis of mobility and facilities (**Figure 3**) reveals a lack of good quality common spaces, a poor and inefficient transport system that makes nearby facilities not accessible. The Battistini metro station (line A), which connects the district

**Figure 3.** *Torrevecchia district: overall analysis.*

#### *Models and Strategies for the Regeneration of Residential Buildings and Outdoor Public Spaces… DOI: http://dx.doi.org/10.5772/intechopen.102366*

with the city centre, is 2 km far from the complex and can be reached in approximately 25 min on foot and in 15 min by public transport. Of the 12 bus lines covering the area, only 4 connect Torrevecchia with the city centre.

Data regarding facilities shows that compulsory schools are insufficient to serve the catchment area. Conversely, there are four technical/professional schools within a 2 km radius of the area under examination. The entire area suffers from a serious lack of facilities which is revealed by the presence of one pharmacy for every 24,500 inhabitants, as opposed to what is required by the Italian law L.362/91 (Art. 1), which is one every 12,500 inhabitants.

Torrevecchia still preserves evident signs of the past rural vocation. The valley between the IACP complex and the Quartaccio district is the least urbanized part of the neighborhood. Despite several green expanses, still not affected by irregular urbanization, the neighborhood is in fact devoid of proper public parks. The only two parks, the Insugherata Nature Reserve and the Pineto Urban Regional Park, are more than 2 km away from the centre of Torrevecchia. Out of more than 65 ha of green areas, only 3% are organized in equipped areas.

Air quality is significantly and positively affected by the abundance of proximity greenery (parks and reserves), although uncultivated and derelict. The average concentration of nitrogen dioxide NO2 is about 32.13 μg/m3 , far lower than the annual limit value for human health protection, established by D.Lgs. 155/2010 which provides for a maximum limit of 40 μg/m3 . As for fine particles, according to what is reported by a PM2.5 map obtained from a dispersion model, the average annual concentration is 18.31 μg/m3 , which is far lower than the limit value of 25 μg/m3 (D. Lgs. 155/2010 in force since 2015).

As regards the microclimatic conditions (**Figure 4**), in the summer season, the area is affected by winds coming from south west (speed of 16 km/h) which considerably contribute to cooling the south-west area that is most of the time subject to direct radiation during the day, given the poor vegetation and the low building

**Figure 4.** *Solar analysis: the tower building in Torrevecchia district.*

heights. The square to the north-east receives just as much radiation, but the layout of the surrounding buildings prevents it from adequate ventilation. In the winter season, the cold wind coming from north east (speed of 9 km/h) sharpens the perception of comfort in the north-east square, which remains cold and in the shade all day long taking into account average winter temperatures of about 7°C. Throughout the day, the south-west square catches the sunlight in its highest part since the shadows cast by the storey buildings are reduced compared to the width of the square.

The tower buildings, especially on the higher floors, enjoy summer ventilation from the south-west but suffer from winter ventilation on the north-east façades, which correspond exactly to the façades with a higher percentage of openings.

The tower buildings, 43.2 m high and with a floor area of approximately 4140 m2 , house 76 accommodations (48 units of 60 m2 and 28 of 45 m2 ) for 248 estimated occupants. A comparison between current users and the availability of floor area, results in 16.7 m2 per person. According to the national legislation, the building should thus house no more than 207 inhabitants. The 60 m2 apartments feature a double exposure while the 45 m2 apartments have a single-exposure. The 60 m2 apartments are designed to accommodate 4 people but both bedrooms (12.4 m2 and 12.8 m2 big) are smaller than 14 m2 , thus do not meet the current minimum standards. It is estimated that the prevalent (50%) family unit typology in Torrevecchia is composed of 1 or 2 members, while families with 4 members account for only 12% of all families.

#### **5.2 Solutions and strategy**

Starting from the overall critical evaluation a project concerning both adjacent outdoor and indoor spaces has been developed with particular emphasis on bioclimatic solutions (**Figure 5**). In the first place, it is essential to redesign the building's connection to the ground, its consequent relationship with the street as well as the intermediate in-between public spaces, to provide meeting and relational opportunities. A necessary prerequisite is an involvement of the inhabitants from the very start, ranging from the preliminary design to the future management and care of common spaces. To integrate the facility system, currently rather inadequate, and enhancing the relationship between building and streets, an elevated square is proposed. The new plaza consists of a solid volume with internal excavated patios and courtyards. Vocational training laboratories, also meant to work as local facilities are located on the ground floors of the towers and in the hypogeal areas beneath the elevated square. A system of ramps allows connecting the different levels on which the public outdoor spaces are distributed. Therefore, the square becomes an open space arranged on two levels on which some food services, laboratories and craft shops open. The internal patios enable to host in the hypogeal spaces several other facilities and services, providing them with adequate light and ventilation and with quality green outdoor space of relevance. The derelict south-west green square is transformed into plots of collective urban gardens managed and used by inhabitants.

When it comes to the tower building, the redesign of the ground connection through an excavation on the short façades (north-west and south-west) strongly contributes to improving thermo-hygrometric and visual comfort parameters of the former basement which is thus freed on two sides from direct contact with the damp ground. The ground floor and the basement are merged to obtain doubleheight rooms suitable for hosting a kindergarten and fab-labs with an external space of relevance gained thanks to the excavation.

To maximize the feasibility of the project, the intention is to limit as much as possible the need for the inhabitants to temporarily leave their homes. Therefore, priority actions address the need to provide all accommodations with adequate living space in terms of square meters to satisfy standards imposed by national law. *Models and Strategies for the Regeneration of Residential Buildings and Outdoor Public Spaces… DOI: http://dx.doi.org/10.5772/intechopen.102366*

#### **Figure 5.**

*Exploded axo: overall project and focus on bioclimatic solutions.*

The addition of plug-and-play modules on the north-east and south-west façades, diversified on a technical level according to the exposure, can solve simultaneously problems related to poor lighting, poor insulation and consequent thermal comfort and under-sizing. The buffer-space modules added to the north-east façade and the bioclimatic greenhouses added to the south-west façade make up new indoor or outdoor living spaces, diversified internally about the type of environment to which they are added and to the needs of the occupants. It's a system of prefabricated

units, ranging from 2 to 8 m<sup>2</sup> big, which add a total of about 10 m2 to each dwelling, which corresponds to 17% additional surface area in the case of the two-room apartment and 14.5% for the four-room apartment.

The bioclimatic greenhouses leaning on the south-east, south-west and south elevations constitute heat accumulation spaces to introduce preheated air into the apartments. The structure is made up of modular steel elements with transparent vertical closures in white solar glass, with a solar factor higher than 70% and with an openable glass surface of 65% out of the overall transparent closure. Sliding panels with adjustable slats in natural fibers and thermosetting resins work like shields. The modules jut out differently according to the functional and structural needs, ranging from 120 to 240 cm. The buffer-spaces, attached to the north-east elevation, highly contribute to improving the overall energy performance, through the reduction of heat loss and consequent thermal gains in winter and through the dissipation of heat in summer. The overhang is 90 cm and the structure is similar to that of the greenhouses but with low-emissivity glass and a solar factor lower than 35%.

New dwellings can be added on the roof, taking advantage of the incentive offered by the regional law L.R. 7/2017 on urban regeneration which allows adding 20% of the original building volume or the original floor surface in case of energy efficiency interventions on residential buildings. The new volumes have a dry load-bearing structure in X-Lam panels and are placed on a load-bearing structure in IPE steel beams to detach and slightly lift the housing module from the existing roof and thus ensure natural ventilation. Each dwelling is equipped with photovoltaic panels (20.50 m2 ) and solar collectors integrated into the roof to assure selfsufficiency in terms of energy.

The original flat roof is replaced with an extensive green roof covered by a pitched canopy which, besides ensuring shading, is also designed to collect rainwater through the central impluvium for irrigating the green roof. The green-blue roof combines different technologies allowing an increase in the storing capacity and a control system of the water flow to release. The green roof helps to cool and humidify the surrounding air, positively affecting the microclimate with slight effects also for the squares located at the street level. In doing so, the storey just beneath the roof slab gains in thermal insulation, therefore less indoor overheating results in less consumption for air conditioning, affecting the overall energy balance. In addition, the vegetated surface effectively protects the waterproofing membrane from UV rays, hail, heat and cold, contributing in the long term to the building envelope maintenance. At the same time, the roof becomes a common space available for all the building users.

Where plug-and-play modules are not applied, an 8 cm sheep wool insulation is laid on the external current envelope to achieve a new transmittance of 0.33 W/m<sup>2</sup> K to ensure an overall optimization of the building energy performance.

#### **6. Linear multi-storey building typology in San Basilio, Rome**

San Basilio (**Figure 6**) is located in the IV municipality, in the north east of Rome, in the urban area 5E, and borders the Grande Raccordo Anulare, an orbital motorway that encircles Rome, to the east and Casal de' Pazzi and Tor Cervara to the west. The municipality is delimited by the via Nomentana to the north, by the municipality of Guidonia Montecelio to the east, by via Tiburtina, the Aniene river, the A24 motorway and the Rome-Pescara railway to the south, and the Rome-Florence railway to the west.

Between 1981 and 1988, the *Piano di zona 02v*—San Basilio social housing urban plan—part of the 1981 supplementary variant of the general urban plan, provided for the construction, based on a project by Antonio Salvi, of 18 linear buildings

*Models and Strategies for the Regeneration of Residential Buildings and Outdoor Public Spaces… DOI: http://dx.doi.org/10.5772/intechopen.102366*

**Figure 6.** *Aerial view of San Basilio district (source: Google Earth).*

of 6–7 floors over an area of 25.5 ha destined to settle 2500 inhabitants. The intervention is not well integrated with the existing fabric and is characterized by an orthogonal system of roads that shapes and defines the various plots. The buildings too are arranged in an orthogonal way and form green courtyards that open up towards the roads and a series of inter-closed courtyards at the points where the building heads come close to each other. San Basilio hosts 6.5% of the ERP accommodations in Rome and about 36% of those in the IV Municipality, gaining first place in terms of ERP accommodations in the city.

#### **6.1 Analysis**

According to the 2011 ISTAT census, it is clear that about 27% of the district inhabitants are between 45 and 60 years old and over half of the families are composed of a single member, 27% of 2 members and only the remaining 20% are families of 3, 4 or 5 components. One-third of the inhabitants have not more than a middle school diploma and only 10% have a university degree, half of the figure for graduates in Rome (20%). The number of unemployed is about 2% higher than the Roman average and about half of the population lives in rented apartments. The neighborhood is also known for the strong presence of petty crime and drug dealing.

Different multi-thematic analyses were carried out concerning mobility, facilities and green systems (**Figure 7**). The mobility analysis highlights how the area under examination is a sort of enclave to the district that stretches to the west, as it is connected to the urban fabric of the old San Basilio district and the rest of the city only by two access roads. The closest metro station is almost 3 km away. A station was supposed to be built in the old San Basilio area but the project for the extension of the metro Line B has never been realized. As for local public transport, although the area is served by several bus lines, these are not sufficient to ensure a direct and rapid connection with the city centre.

With regard to the facilities, since there are no public or private ones within a radius of 250 m from the area under examination, and only a mechanic within a radius of 500 m, one is forced to travel almost 1 km to reach a supermarket, pharmacy or the nearest primary school. 57% of the district facilities are ascribable to retail trade, while public space meant for squares does not exceed 2%.

The several parks and green spaces in the area are unequipped and poorly maintained. In general, the outdoor spaces lack even the most basic elements of street

**Figure 7.** *San Basilio district: overall analysis.*

furniture. This leads inhabitants to use these spaces only to go from one place to another and not for social purposes. Moreover, inadequate public lighting increases the feeling of insecurity among the inhabitants.

The microclimatic analysis (**Figure 8**) shows that the area under examination is affected by cold winter winds coming from east, north-east (about 9 km/h) and by hot summer winds coming mainly from south-west with a speed of approximately 16 km/h. In the summer season, both the north-east square and the southern square adjacent to the building suffer significant overheating phenomena throughout the whole day, yet moderated by ventilation. In winter, the northern square lays most

*Models and Strategies for the Regeneration of Residential Buildings and Outdoor Public Spaces… DOI: http://dx.doi.org/10.5772/intechopen.102366*

**Figure 8.** *Solar analysis on the linear building in San Basilio district.*

of the time in the shade and is constantly exposed to cold winter winds due to the absence of adjacent buildings.

The building under consideration (6G) is a linear multistorey building typology of about 42 × 13 m consisting of 7 floors above ground and a basement floor. The building currently houses about 135 people for a total of 45 apartments of 50, 60, 80 and 100 m2 , accounting respectively for 40%, 30%, 25% and 5% of the total housing units. The structure is in reinforced concrete bearing walls that define a succession of different sized spans parallel to the short side. The façade is characterized by prefabricated concrete blocks with a minimum insulating layer of glass wool. The joints have not been carefully designed and the discontinuity of the insulating layer causes several thermal bridges. The building is equipped with two staircases and the access is via a gallery located on the ground floor at a height of +1.00 m, above the cellar floor, accessible from the condominium staircases. Currently, the ground floor houses, in the eastern part, two special housing units for people with physical disabilities and two rooms initially designed to be a condominium space and a laundry for common use. At the moment, the western part is occupied by storage spaces but it was meant to be—according to the original project—a *pilotis* floor with a walkway at a height of 0 m from which to access the gallery via the staircase. The upper floors house the apartments and each staircase serve from 3 to 4 units, two-thirds of which have single exposure. The living spaces do not face undersizing problems since all the indoor spaces meet the minimum surface and height standards for public housing and besides, aero-illuminating ratios are verified in all rooms. The staircases lead up to the roof level.

#### **6.2 Solutions and strategy**

The analysis of the current condition reveals the need to rethink the building in all its aspects (**Figure 9**) starting from its connection to the ground not only in terms of spaces and functions but also about the square in front. The special apartments

#### **Figure 9.**

*Exploded axo: overall project and focus on bioclimatic solutions.*

on the ground floor are to be relocated, in terms of living space, on the roof level and the currently unused common spaces are to be converted into local and building facilities chosen according to what emerged from the previous social analysis. In rethinking the relationship with the outdoor spaces, the current gallery at a height of +1.00 m is redesigned in terms of accessibility, use and relationship with the square, providing for its expansion in some points to create terraces to serve the new activities and rest areas to encourage meeting and socialization occasions. A co-working, refreshment and internet point could be located in the western part of the ground

#### *Models and Strategies for the Regeneration of Residential Buildings and Outdoor Public Spaces… DOI: http://dx.doi.org/10.5772/intechopen.102366*

floor (internal height of 3.70 m) at the same level as the square and near the main road. These spaces are thought of as facilities for the entire local community. The remaining part of the same floor (with an internal height of 2.70 m) could host a series of flexible spaces, including a medical-assistance clinic with an adjoining small outpatient clinic where professionals can offer different services on shifts, multipurpose spaces for courses and activities and a bicycle repair workshop.

Overall, the existing envelope does not meet current national standards for energy performance for buildings. In this regard, a new insulation layer must replace the previous thin and inadequate one together with the application of a ventilated façade in specific parts. Old windows are replaced by new ones in recycled aluminum with thermal break and double glazing with argon gas inside, with a global transmittance of 1.56 W/m2 K compared to the maximum 1.80 W/m2 K required by law.

The current design of the housing units of the standard storey does not make the most out of the living space. A new distribution of indoor spaces in favor of living areas located south and an implementation of new spaces to increase liveability, are required. In this regard, steel plug-and-play modules added to the façade, besides providing additional volume, can also be configured as bioclimatic devices by hosting greenhouses or buffer spaces depending on the orientation or, in some cases, as balconies or galleries. To make the housing units more compliant with the family units—according to socio-demographic data—one standard storey could be turned into a cohousing for about 40 members. This housing typology, mainly designed for relatively young users, single or couples, spreads over one entire floor and is accessible from both staircases. The sleeping area is essentially located in the east and west wings and the north. The south front instead hosts several shared spaces in sequence, such as a kitchen equipped with a dining area, a common living room, a mini cinema/games room and a common laundry room, all joined by a single glazed connection placed in adherence to the south façade. To ensure adequate ventilation inside the single-exposure apartments (about 60% of the total), a geothermal cooling/heating system operated by wind towers is inserted. In the light of the microclimatic analysis, the tower collection heads should be placed where airspeed accelerations occur both in summer and in winter. The air is trapped and then directed through underground ducts—where thanks to geothermal energy it is pre-heated/cooled depending on the season—to the apartments to be, in a second step, introduced into each room through a distribution system installed in the false ceilings positioned over the service and distribution spaces.

With regards to the roof, the availability of such a large free surface allows the implementation of different passive and active strategies as well as technological devices. Special housing units (once located on the ground floor) and common spaces are relocated on the roof. These new accommodations, larger and suitable for families of 4–5 members, have been designed for a different target audience, to encourage different people to approach the neighborhood and thus promote social *mixitè*.

Moreover, a common laundry room, a greenhouse for food production and a common outdoor kitchen/dining area are integrated as new volumes on the roof. The roof is also equipped with a system for the collection and reuse of rainwater and gray water. The uncovered surfaces are redesigned to better capture rainwater and convey it to specific collection points. From here, the water is filtered and purified and then used for cleaning and irrigation purposes for outdoor spaces, toilet drains and washing machines. With regard to gray water—before being stored in the collection point—it undergoes a different purification process and is later reinserted into the general circuit. This system can bring about significant clear water savings accounting for about 20%. The building is also equipped with a photovoltaic system for electricity production. The system is composed of polycrystalline modules of the size of 50 × 50 cm with a nominal power of 35-W peak

each. The energy produced, equal to about 17,000 kWh per year, will feed, not only the lighting system—replaced with LED elements—but also the heat pumps for the underfloor heating system and part of the domestic consumption. A small portion of the roof is also meant for a solar thermal system for domestic hot water production, consisting of 18 panels of about 2 m<sup>2</sup> , for a total of 36 m2 , able to cover 50% of the annual housing needs.

#### **7. Results and conclusions**

Currently, most of the interventions on ERP have an emergency nature: direct operations aimed at solving specific problems in the short term. This logic, devoid of investment, does not allow to respond to broader issues, without halting the heritage deterioration. Today it is even more necessary to outline intervention strategies capable of coping with the technical-functional aging of buildings. The ERP heritage of the city of Rome can become the key element for a qualitative regeneration of the city. According to socio-demographic data, it is possible to point out similar contexts, characterized by strong social unrest, petty crime and a high unemployment rate (23% in Torrevecchia and 16% in San Basilio). About the district population, that of San Basilio is generally younger and made up of larger families compared to that of Torrevecchia. Yet, in both cases, the most recurrent family unit is composed of 1 or 2 members. Not only the different characteristics of the plano-volumetric system but also those related to the socio-economic, environmental and microclimatic context play their part in the choice of which strategies and solutions implemented.

The study carried out allowed to investigate and compare the limits and the potentialities deriving from the building typology and its plano-volumetric system:


#### *Models and Strategies for the Regeneration of Residential Buildings and Outdoor Public Spaces… DOI: http://dx.doi.org/10.5772/intechopen.102366*

which consequently face serious problems related to indoor ventilation. This aspect is mainly linked to the need for a greater surface area for connection purposes to serve all the apartments. Unlike linear typologies, in tower buildings, the connective surface is reduced to the least and corresponds to the stair and elevator block. On the other hand, the linear typology allows greater freedom in redefining the standard floor plan by changing the dimensions of the existing housing units to adapt them to the user's needs. About the apartments, in Torrevecchia their dimensions were deemed suitable for the users and more than two-thirds of them have double exposure. In the case of San Basilio, this proportion is roughly the opposite, with % single exposure apartments accounting for 60%. As mentioned above the single exposure led to the introduction of wind towers to improve ventilation in indoor environments. Some of the apartment rooms in Torrevecchia, such as the double bedrooms, do not meet the minimum standards required by law. Therefore, the addition of new plug-and-play modules on the façades allows for to increase in the limited current surface area and meets the standards.

	- A photovoltaic system for electricity production: the larger roof surface allows to install a more powerful photovoltaic systems capable of satisfying a higher share of electricity consumption. In the linear typology, the cost is maximized, since it does not require any integrated systems on the façade, and since the system is more efficient thanks to the possibility of positioning the panels according to the best exposure.
	- Rainwater collection system: the larger collecting surface allows to accumulate a greater quantity of water, achieving far higher water-saving percentages.

Furthermore, greater space availability also results in the possibility of adding new accommodations and several common spaces such as a laundry room, multipurpose rooms and a common kitchen in order to provide the inhabitants new spaces in which to spend time and do activities together.

Although, the building typology is quite significant in defining the different possible intervention strategies, these must necessarily be contextualized according to the specific study/project area and its *genius loci*, in other words, the sociocultural, architectural, economical habits and characters of the place.

#### **Conflict of interest**

The authors declare no conflict of interest.

*Sustainable Development Dimensions and Urban Agglomeration*

### **Author details**

Alessandra Battisti\*, Livia Calcagni and Alberto Calenzo Department of Planning, Design, and Technology of Architecture, Sapienza University of Rome, Rome, Italy

\*Address all correspondence to: alessandra.battisti@uniroma1.it

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Models and Strategies for the Regeneration of Residential Buildings and Outdoor Public Spaces… DOI: http://dx.doi.org/10.5772/intechopen.102366*

#### **References**

[1] UN Desa. Transforming Our World: The 2030 Agenda for Sustainable Development A/RES/70/1. New York: United Nations; 2015

[2] European Union. European Commission. Directorate-General for Regional Policy. Cities of tomorrow: Challenges, visions, ways forward. Brussels: Publications Office of the European Union; 2011

[3] European Commission. Report from the Commission to the European Parliament and the Council. 2020 Assessment of the Progress made by Member States towards the Implementation of the Energy Efficiency Directive 2012/27/EU and towards the Deployment of Nearly Zeroenergy Buildings and Cost-optimal Minimum Energy Performance Requirements in the EU in Accordance with the Energy Performance of Buildings Directive 2010/31/EU. Brussels: European Commission; 2020

[4] IEA. Sustainable Recovery. World Energy Outlook Special Report in collaboration with the International Monetary Fund. Paris: IEA Publications; 2020

[5] EU SHREC | Interreg Europe: Renovation Wave Strategy Targets European Buildings. Retrieved from SHREC | Interreg Europe. [Internet]. 2020. Available from: https://www. interregeurope.eu/shrec/news/newsarticle/10397/renovation-wave-strategytargets-european-buildings/#:~: text=Commissioner%20for%20 Energy%2C%20Kadri%20 Simson,green%20recovery%20 starts%20at%20home.&text=The%20 Strategy%20will%20prioritize%20 action [Accessed: April 10, 2021]

[6] Corrado V, Ballarini I, De Luca G, Primo E. Riqualificazione energetica degli edifici pubblici esistenti: direzione nZEB. Studio dell'edificio di riferimento uso uffici della PA nella zona climatica Nord Italia (zona E: 2100< GG≤ 3000). Report RdS/PAR2017. Roma: ENEA; 2018

[7] OECD. Integrating Distressed Urban Areas. Paris: OECD Publishing; 1998. DOI: 10.1787/9789264162884-en

#### **Chapter 13**

## Urbogeosystemic Approach to Agglomeration Study within the Urban Remote Sensing Frameworks

*Sergiy Kostrikov and Denis Seryogin*

### **Abstract**

The spatial arrangement of human activity within urban areas is normally provided by areal management, and its effective provision is a complicated problem. The current urban development causes a number of problems and urgent challenges, which can be met and resolved exclusively on the basis of innovative scientific and technological advances. The main research objective of this chapter is to represent the authors' theoretic concept of the urban geographical system combined with the original Urban Remote Sensing approach based on the advanced technique of airborne LiDAR (Light Detection And Ranging) data processing. The authors attempted to prove that the presented concept could contribute to an understanding of the urban agglomeration as an urbanized spatial entity. The chapter explains in what way the urbanistic environment is a quasi-rasterized 3D model of actual city space, and the urbogeosystem (UGS) is a quasi-vector 3D model of the hierarchical formalized aggregate of UGS elementary functional units–buildings, both can efficiently simulate and visualize an urbanized area. Web-based geoinformation software for LiDAR data processing with the objectives of urban studies has been introduced together with its key functionalities. The population estimation use case has been examined in detail within the presented approach frameworks.

**Keywords:** urbanistic environment, urbogeosystem, urban remote sensing, LiDAR, automated feature extraction, web-based software, population estimation use case

#### **1. Introduction**

The continuing significant growth of population all over the world, but, first of all, in developing countries, forces scientists to seek new advances and solutions in Demography and Urban Studies domains. These two subject areas primarily mean increasing involvement of the innovative approaches and techniques related to geoinformation technology (GIS) and to the urban remote sensing (URS) field [1–3]. Since the continuing growth of the total world population takes place together with the phenomenon of urbanization, the relevant information systems intended for the survey of these two connected processes have to possess some bidirectional modeling and analyzing characteristics, which would overlap both demographic and urbanized issues.

We have just mentioned the significance of remote sensing data processing and GIS-modeling tools to the mentioned extent. This role can hardly be overvalued, taking into account that many from contemporary cities and their affiliated areas have become to act for several recent decades as more and more complicated *urban systems* with drastic dynamic changes within the relevant geographical space and with systemic specific impact on involved people movement and behavior [4–7].

If *an urban agglomeration* can be considered as a highly developed spatial entity of urbanized areas [8], then the approach of *the urban geographical system – urbogeosystem* (UGS) [3] should be applied for examining a number of relationships among the constituents of this system, which may definitely demonstrate its core feature – *the complexity.* Since the complexity is a key description of the contemporary urbanization process too, a whole issue of the spatial urban regularities may require to be evaluated by taking into account not only spatial but purely geographic issues. Both the mentioned rapid urbanization growth, and its attendant alterations in old, and in new cities do not allow to examine any other alternative to an acceptance of a city phenomenon as this just mentioned entity – *an urbogeosystem*, which operates within a certain extent of the geographic space.

It is also necessary to emphasize that the key characteristics of contemporary urban development, which has its effect in forming agglomerations, have caused a number of challenges that require innovative technologies in urban studies. These challenges and responses to them can be summarized in the following way [9]:


Although the urban areas cover only 2% of the globe surface in recent years, they include more than half of the world population, and consume more than three-quarters of the total generated energy. The latter produces more than 80% of the greenhouse impact [10]. It is understandable then, why a problem of optimized growth of urban settlements has been a major problem for residents, urban developers, and city authorities for many centuries already. The category of "urbanism" itself appeared more than a century ago [11], while the first statement that an urban agglomeration might represent the core definition in the theory of urbanism occurred with the introduction of the "megalopolis" entity in the middle of the

*Urbogeosystemic Approach to Agglomeration Study within the Urban Remote Sensing Frameworks DOI: http://dx.doi.org/10.5772/intechopen.102482*

twentieth century [12]. The author of this latest reference stated that routine urban areas gradually would transfer into mentioned megalopolises by joining and changing nearest semi-urban areas and rural neighborhoods. Monitoring this settlement growth became more and more complicated phenomenon, that was why some further research focused on the necessity of the urban system approach together with various sophisticated mapping techniques, which we have mentioned already at the beginning of this introduction [4, 6, 13].

Data of various remote sensing approaches, different GIS platforms, and modules provide the application of a variety of modeling techniques for resolving fundamental riddles related, for example, to spatial dimensions of the agglomeration growth. These techniques may belong to different scientific domains, e.g., fractals and theory of chaos [14], unsupervised classification [15], the algorithm of cellular automata [16], fuzzy logic [17], automated feature extraction [18], analytic hierarchy procedures [19], urban change detection [20], and several other ones. Even being quite diverse, all mentioned methodical solutions can effectively contribute to both estimations of the urban agglomeration expansion to the neighboring rural environment, and to the description of a relevant urban system according to key features of its internal and external relationships and impact.

The main **research objective** of this chapter is to introduce the authors' theoretic concept of the urban geographical system, and this concept is combined with the original URS approach to simulation of *the urbanistic environment* as a model of *a real city domain*. This urban remote sensing approach is based on the advanced technique of airborne LiDAR data processing. A use-case of population estimation on the base of building geometries and topology of urban space both modeled within the urbogeosystemic approach is described in detail in the finalized section of the chapter.

#### **2. The concept of the urban geographical system**

Earlier research completed in the fifties-seventies of the past century normally defined an urban system as not more significant entity, than a straightforward set of cities (or smaller settlements combined in a united urban territory) with some relations among these separate units. Nonetheless, there were two seminal books in the second half of the seventies, which represented some *regular structure* in the systems of cities [4, 21]. Probably, these publications were that trigger, which initialized actual urbo-systemic research somewhat later. The authors insisted, that they merely summarized within an applied perspective some concepts and methods, that had been developed as earlier as in the fifties [21, 22]. Although, all these publications, from our point of view, represented only few relevant research samples, which could be reliably determined as some phenomena of the pure emergent features of either a system of the city (separate districts within one urban area as a systemic entity) or a system of several different cities.

Introducing once a definition of an urban geographical system [3, 9], we attempted to extend and develop some basic ideas of the urban system delineation represented by various scientists in former publications [4, 6, 23, 24].

Empty city spaces between buildings and other infrastructural objects within urban territories are much more complicated according to their daily dynamics than they were even 10 years before. It means the schedule of these spaces filling during a day with residents, both static, and moving objects has altered drastically. By choosing the appropriate GIS-modeling technique we can simulate the mentioned dynamics and record it in a certain formalized mode within the frameworks of the model of the urbanistic environment mentioned above.

*The urbanistic environment (UE) is a quasi-rasterized model of a continual nature of actual city space and this space key features, which can be visualized as a space limited by various surfaces and can be represented directly by these surfaces*. Thus, it can be reasonable to suppose, that the UE also possesses a continuality of the object it represents. The UE continual nature can be contrasted with *the discrete nature of an urbogeosystem – the hierarchical formalized aggregate of elementary functional constituents of its natural analog, which may demonstrate some emergent (systemic) properties. The UGS can be visualized by various 2D vector graphical primitives on a plain (points, lines, polygons), and by quasi-vector 3D primitives in the three-dimensional space.* All emphasized 2D/3D primitives combine a particular *formalized view of the urban space.*

Taking into account modeling characteristics of UE and UGS, quasi-rasterized and quasi-vector ones, correspondingly, and referring to the essence of real objects both models represent – physical environment of a real city (modeled by UE) and sets of separate features in it (simulated by UGS), a research and developing procedural consequence *Initial/derivative data = > UE= > UGS* can be easily placed within the frameworks of raster-vector transformations. The latter is a subject of routine GIS functionality. Applying this functionality is the only understandable procedure, which can contribute to answering the question: if a given city does rather belong either to urban systems or to *urban sprawl* [25].

The first outlining of the urbogeosystem was suggested in our earlier paper and it laid in a completely ontological aspect. According to it, an urbogeosystem is "…The UGS is an urban system located within a definite extent of the geographic space; it is an unsustainable social-environmental system which is also a united entity of various architectural features and dramatically changed natural ecosystems…" [3, p. 110].

Those literature sources, that introduce various descriptions of *the urban system structure* [4, 6, 21–24, 26], imply each separate systemic component in a set of cities as *a point feature*, while interconnections and relations between each pair of these single objects – as *a linear feature*. Then a certain group of cities within the boundaries of a definite region, are located in a certain *areal feature*. Instead of "a city" as a separate unit, we can accept "a city ward (district)", then obtain a set of such units within a particular urban territory. In this way, we can enter a completely another research scale, but in both larger, and smaller scales points, lines, and areal fragments (regions or parcels) are key components of an urban geographical system. The geographical scalability can be applied then, while a single object (a city or a ward) is *a point* in one scale, but on another, larger scale it becomes *an area.* In a similar way, we can apply scalability to *the lines* and obtain the linear features of different magnitude [7, 9].

Let us assume that initially, a set of *N* cities indicates some *N\*N*-matrix, in which "point cities" interact in different terms of human, industrial, trade, transportation, and information traffic, composing a picture of *an external urbogeosystem*. On the first step of scalability, a matrix would also define a number of linear features, which mirror spatial linkages in *an external urbogeosystem* in the mentioned terms. On the second scalability step, not the same, but similar matrix depicts *N* districts of one city only and all interconnection pairs among them, which exist in an *internal urbogeosystem*. In the simplest definition, it is a set of districts in one city, as we already mentioned.

On the basic fundamentals of the UGS approach introduced above, we elaborated and proposed *the algorithmic sequence of the UGS research with GIS tools* [3]. It consists of several algorithmic blocks that sustainably combine a thematic geographical model, urban remote sensing technique, and both basic and customized GIS functionalities. The key algorithmic blocks in this scheme are as follows (**Figure 1**):

*Urbogeosystemic Approach to Agglomeration Study within the Urban Remote Sensing Frameworks DOI: http://dx.doi.org/10.5772/intechopen.102482*

**Figure 1.** *The algorithmic flowchart of the UGS study with GIS tools [3, p. 111].*


We have already published several papers in the urbogeosystem approach, examining various aspects of this concept: its basic fundamentals [3], its applicability to the Smart City concept implementation [9], its possible involvement in the multifunctional approach to the 3D city modeling [27], some from UGSbasics were applied to the structural analysis of agglomerations in Kharkiv region (Ukraine) [28]. The latest research accepted a well-known definition of agglomeration as a large city (as an agglomeration core) with all its nearest townships and


#### **Table 1.**

*The corresponding agglomerations and urbogeosystems hierarchy for the Ukrainian population settlements (an updated table from [28, p. 4950]).*

the suburbs. We attempted to define that all these settlements are characterized by various interrelations. Thus, a new entity of aggregated functioning appears, which is common for this big urban territory, and for small towns and villages around it. This urbanized compact entity of settlements was accepted as a spatial systemic formation with all relevant features of the urban geographical system. Therefore, it can be reasonable to apply to an agglomeration study that algorithmic flowchart presented in the illustration above (**Figure 1**). Socio-geographical survey over the East of Ukraine, in particular – within Kharkiv region, proved that agglomerations as spatial patterns of different hierarchical levels can be delineated, not only as social geographical systems (SGS), but also as both external and internal urgogeosystems, and they are significantly present in the territorial arrangement of this region. Taking into account the general concept and the surveyed results, we suggested the hierarchy of the delineated agglomerations with respect to the necessary update of the territorial division of Ukraine (**Table 1** is updated from [28]). Thus, a regional system of settlements has been proven to be not only a mosaic of all five agglomeration levels, which may overlap each other in the spatial extent but also – *the spatial hierarchy of urbogeosystems*. Consequently, the local agglomerations are the urbogeosystems of the fifth, lowest rank. In other words, they are basic units, elementary ones in the common hierarchy for both urbogeosystems, and for agglomerations. It follows from **Table 1**, that various hierarchical levels of the settlement spatial structure can be distinguished – from microlevel to mega-level, and these levels correspond to a particular social geographical system, and to a particular urbogeosystem.

Concluding the second section of this chapter, which has introduced the UGS approach with this example of agglomeration research, it is necessary to address the following issue. This approach can be directly provided for examining agglomerations according to its main features introduced in this chapter section:


*Urbogeosystemic Approach to Agglomeration Study within the Urban Remote Sensing Frameworks DOI: http://dx.doi.org/10.5772/intechopen.102482*


Further in this text, we examine some steps of this consequence more in detail, while taking it for granted, that a strong spatial aspect of the urban research necessarily implies the GIS/URS processing procedures, tools, and operations efficient involvement in this research, what we attempt to outline as various issues in the text below.

#### **3. Urban remote sensing with LiDAR for digital cities**

#### **3.1 Automated feature extraction**

Automated reconstruction of the sets of various buildings is yet a serious challenge on the way to 3D digital city modeling. Other significant tasks can be affiliated with it, for example, outlining the Smart City concept implementation [9]. Exactly for the two latest decades, LiDAR data and its processing results have become real alternative data sources to optical and multispectral imageries with respect to generating a three-dimensional representation of urban territories [2, 29, 30]. Being able to collect straightforwardly dense and accurate 3D point clouds over both urban, and rural features, the technology of the LiDAR survey provides a reliable and beneficial data source to this end. Almost all LIDAR devices are either Airborne types (ALS, aircraft-based) or Terrestrial (Mobile, MLS) (vehicle-based), as well as drone-platform ones.

The key processing and simulated procedure intended for building digital cities, while the latter is a basic fundamental for urbogeosystem delineation, is the *automated feature extraction* (AFE) from point clouds generated by LiDAR [31]. Normally the automated feature extraction is based on both optical satellite images of high resolution, and on LiDAR datasets generated by airborne, terrestrial, and drone platforms on regional surveys [32]. The latter ones are usually provided by strips and then combined as three-dimensional point clouds [2]. AFE output is the key tool that makes digital urban models. Various approaches, methods, and solutions that *detect*, *extract*, and *generate* building models with any selected alternative technique, all compose a highly significant research domain [33].

This latter statement can be accepted by default, because a whole approach mandatory means 3D automatic, but desirably - *smart mapping* of the multi-scalable urban environment, that is of the extreme complexity. Moreover, as it has been mentioned already if exactly LiDAR data become in recent decades an efficient alternative to imageries obtained by traditional satellite remote sensing, then this data source should become a subject for various approaches and algorithms, as previously traditional URS was. These approaches and algorithms should differ for various procedural stages, and suggest robust solutions separately for 1) building detection, 2) extraction and 3) building reconstruction steps [34].

The automated building/other infrastructural feature extraction procedures can be fulfilled by three sub-procedures, as was already stated above, i.e., building detection, building extraction/segmentation, and building reconstruction [34–36]. All three sub-procedures mentioned may not be clearly distinguishable. To complete a single stage of automated extraction of buildings may not yet be satisfactory enough for practical applications due to the great complexity of actual urban architecture, which we always face while modeling the urbanistic environment on the first step of the urbogeosystem delineation. Different additional sophisticated algorithmic solutions should be involved, for example, those ones, which assist in distinguishing between building constructions and urban vegetation, while processing an airborne point cloud [37].

Traditionally being within the frameworks of our original multifunctional approach to LiDAR point cloud processing [27, 31, 38, 39] we have to consider only those methods, which use exclusively LiDAR data, so that to utilize the building geometric and topological properties only, and not any other urban landscape characteristic except *urban topography*. In this way we have to pass through the mentioned above trinity of steps: building detection, segmentation, and reconstruction ones, while topography is generated upon the first step from these three while discriminating so-called "ground" and "non-ground" points when processing LiDAR datasets.

It is commonly accepted understanding that the model, which includes not only the ground as the topography, but other features – the discrete ones, is not a digital elevation model (DEM), but *a DSM – a Digital Surface Model.* According to existing references before the sustainable usage of LiDAR point cloud for topographic modeling, the digital surface model was normally calculated using various imageries, hybrids (imageries + point clouds), and feature pyramids [40]. The final DSM surface is refined then on the base of local adaptive regularization techniques provision. While the urban topography has been generated already, the building detection step is grounded on the fact that buildings, as a rule, should be higher than the neighboring topographic surface. This is normally estimated using various mathematical morphology techniques through the DSM [41].

In our original approach to LiDAR point cloud processing with the intention to separate "ground" and "non-ground" point as a mandatory premise for further nonground features detection, segmentation, and reconstruction, we have provided the following steps, which can be introduced in the following summarized way proceeding from several relevant references [27, 31, 39]. The initial unique step assumes the delineation of both DEM and a DSM from the airborne point cloud raw data, in which point density should be preferably within a range of *10–80 points per square meter*. The proposed method of DEM generation accomplishes a classification of the original data as "ground" points versus "non-ground" points by robust estimating procedure, which has been described in detail in one of our latest papers [39]. In all consequent algorithmic steps of modeling UE, the *heavyweight models* generated by triangulation and interpolation, and *lightweight models* generated by clustering and segmentation are used, but not the original data points. DEM is subtracted from the DSM. The output results of building detection and segmentation, i.e., the delineation of individual building footprints can be provided with a connected component analysis. A set of the selected feature candidate regions can be arranged. Then a planar surface segmentation can be executed, is based on the analysis of the DSM vector variations. The output result of this step is crucial for finding planar parcels of buildings. These parcels are expanded then by applying a bunch of the region growing algorithms. The neighborhood connections of these parcels are determined, and a simplified model resembling the roof structure in a certain building is generated. A Voronoi diagram can be created for extraction of neighboring joints and connections of numerous facets that compound roofs and walls in the heavyweight models, while planar segmentation and customized topological rules are used for segmenting and combining lightweight models of simplified buildings with gable roofs.

*Urbogeosystemic Approach to Agglomeration Study within the Urban Remote Sensing Frameworks DOI: http://dx.doi.org/10.5772/intechopen.102482*

**Figure 2.**

*Some key constituents of the AFE-pipeline are intended for the generation of both urban topographies, and building models from LiDAR point clouds.*

A summarized AFE-pipeline relevant to LiDAR data processing, which contains some of the basic fundamentals presented in this subsection, is visualized on the following flow-chart composed by this chapter authors (**Figure 2**):

The flowchart presented not only depicts the main components of the automated feature extraction pipeline but also is some kind of a presentation due to the digital city content creation. The latter with the introduced UGS approach consists of two phases, as we already explained:

1.modeling the quasi-rasterized UE, and

2. simulating the quasi-vector UGS.

Both phases contain in one way, or in another all six blocks of this flowchart. Nonetheless, the *first phase* (directly affiliated with modeling the UE) does definitely include the *urban data mining* complex (*Import*, *Validate*, and *Add Value* blocks), while *the second phase* implies the implementation of pre-processing, processing, and simulating solutions (*Split*, *Process*, and *Merge* blocks) for the presentation of the three-dimensional geometry of each separate building and sustainable topology for the sets of buildings in a digital city. The output results of the flowchart, which is in **Figure 2**, may be provided in several formats, e.g.,. gLTF,. K*LM*,. D*AE*,. B*3DM*, etc. Nonetheless, a core inner format is. *OBJ.* Simulated features of a digital city are produced with the representation of their borders. A whole *3D urban scene* can be depicted as a set of building constructions with the continuality of their bounding walls, vertices, edges, and supplementary outhouses, and this continuality can be described by certain parameters of *urban geometry*. In this way, the urbanistic environment is simulated. Due to the mentioned continuality, a scene can also demonstrate the topological interdependencies of buildings

#### **Figure 3.**

*The urbanistic environment and a fragment of the UGS modeled for a district of Washington, D.C. (USA) and visualized in the interface of a cloud processing platform: EOS LiDAR tool – ELiT cloud.*

among themselves and with non-housing urban features and various infrastructural objects. Urban features are visualized according to the *CityGML* LODs (Level of Detail) standards [42].

Thus, a partial fragment of an internal urbogeosystem can be modeled and visualized in the 3D scene with spatial, geometric, and semantic characteristics, which can be exposed for each selected feature, or for a number of them. A number of LOD 1 (a simplified box-model of a building) models that correspond to the CityGML 2.0 concept are visualized for the Washington, D.C. urban area in the interface of a web-GIS software, in which elaboration participated both of this chapter authors. This interface sample relates to the cloud processing platform of this software (**Figure 3**).

Our models of urban objects exposed on the illustration above possess all necessary characteristics of 3D digital city models. While many other three-dimensional objects seem to be predominantly used for display, it is reasonable to emphasize that these simulated features presented in a 3D Scene can be increasingly employed in a number of domains within a large range of tasks beyond the direct visualization. Such perspectives can be opened if we accept simulated sets of building models as the aggregations of elementary functional features of an urbogeosystem. The reasonability of such an assumption has been proved by the authors in some previous publications [3, 9, 39].

#### **3.2 Web-based geoinformation software for the urbogeosystem approach implementation**

We have already mentioned that both authors of this chapter participated in research and development (the first author – as ahead of this R&D) of the webbased and cloud-based versions of the geoinformation software focused on LiDAR data processing for urban studies, what took place in the EOS Data Analytics Company (https://eos.com/eos-lidar/). Common fundamentals of the Automated Feature Extraction determine our core algorithmic structure named as the *High Polyhedral Modeling* (HPM) and elaborated within the frameworks of the integrated *BE (Building Extraction)* /*BEF (Building Extraction with Footprints)* /*CD (Change* 

*Urbogeosystemic Approach to Agglomeration Study within the Urban Remote Sensing Frameworks DOI: http://dx.doi.org/10.5772/intechopen.102482*

*Detection)* /*DEM-G (Digital Elevation Model Generation*) functional pipeline of ALS/ MLS data processing [27]. HPM produces building models with numerous facets.

According to the whole HPM workflow, two following problematic issues may occur with great probability: #1 – to provide more precise classification of both "vegetation" points, and "building" points is crucially necessary; # 2 – to elaborate a definite method in what we have to define the building topological and geometric properties in those cases when point cloud data are incomplete. All possible solutions for both issues should be preliminary outlined, and we took it into account while developing our basic original algorithm of LiDAR data processing and proposing some supplementary technique that has to be accomplished in parallel with core algorithm operation.

Within frameworks of our conceptual R&D approach buildings are accepted as the key man-made features in the modeled urbanistic environment. According to the HPM output results it consists of numerous continuous surface segments (polyhedrons) that compose *the trinity content of the city space*: urbanized topography, building surfaces, and empty urban spaces between buildings that are separated by two previous issues.

There are two platform versions on which *EOS LiDAR Tool*, *ELIT* software, can operate: a cloud processing version, as *ELiT Cloud*, that applies to AWS instance service power (**Figure 3**), and a typical client–server, web-based application as *ELiT Server*. The urbanistic environment of Toronto-City as a model reconstructed by the HPM pipeline may look like follows in the *ELiT Server* interface (**Figure 4**).

Corresponding functional tools of both *ELiT-*software platforms, which are set within the HPM frameworks are *BE*, *BEF*, *CD*, and *DEM-G* tools. The *BE/BEF* tools extract *original building footprints* from point clouds while modeling [39, 43].

In addition to the High Polyhedral Modeling, we have developed the alternative AFE-technique, such as is the Low Polyhedral Modeling (LPM) approach, which is based on procedures of planar segmentation and clustering of LiDAR point clouds rather, than on their classification (in the case of HPM). The LPM technique is primarily intended to extract low-rise buildings of either rural areas, or city suburbs

**Figure 4.** *The UE of Toronto-City (Canada) is modeled in the ELiT server interface.*

#### **Figure 5.**

*Lightweight models of elementary functional constituents of the urbogeosystem of Lubliniec-City (Poland) in the ELiT cloud processing platform interface.*

as light-weighted models, which consist of only a few facets. The relevant functional tool of the LPM approach is the *BERA (Building Extraction Rural Area*) tool. The *BERA* instrument employs *the third-party building footprints* while modeling [39, 43]. If the HPM-technique with its *heavyweight models* is more preferable for simulation of the quasi-vectorized UE (**Figure 4**), then the LPM-method – for creation of the 3D quasi-vector *lightweight models* of buildings and other features as elementary functional constituents of a certain urban geographical system (**Figure 5**).

If not taking into account such research entities as UE and UGS, but evaluating only building modeling itself, then it can be emphasized, as we have already mentioned above, that the BERA functionality is an application for detection, extraction, and modeling of low-rise housing located in city suburbs and urban areas. The HPM approach is recognized to be more efficient for simulating high-rise buildings of downtowns.

Contrary to HPM, with which the BE tool is affiliated, this alternative AFE technique, LPM, and the *BERA* tool, as it has been already underlined, are strongly based on planar segmentation, clustering, and reconstruction of polyhedral building models. In comparison with the HPM pipeline, both planar segmentation and clustering substantially decrease the number of polyhedrons as constituents of a building model extracted. Thus, we attempted to provide an efficient update and an applied realization [43] of the advanced theoretical approach known as segmentation and reconstruction of polyhedral building roofs [18].

Both software, a client–server application, and a cloud-processing platform can be run from a web browser installed on a user's workstation. According to its architectural scheme, the *ELiT* software performs transmitting procedures between the Processing Core, that is on a server, and a Client, while providing such operational sets as Data Management (uploading, downloading, etc.), Task Management, and interactions between the Core and a database. Finally, a Client provides a user graphical interface and the building model/topographic surface visualization. A Java Script based library - *Cesium 3D Tiles* is employed for this display, https:// cesium.com/

*Urbogeosystemic Approach to Agglomeration Study within the Urban Remote Sensing Frameworks DOI: http://dx.doi.org/10.5772/intechopen.102482*

#### **4. Population estimation and mapping on the base of elementary functional units of an urban geographical system**

Urbanistic environment and urbogeosystem modeling on the base of automated building feature extraction, further mapping of extracted and reconstructed features, and finalizing 3D digital city generation for both urban, and rural areas can be highly essential for many industrial applications. It would be reasonable to define four next key categories of the urbogeosystemic approach in its applied perspective. Each of these categories may directly relate to an agglomeration study: 1) common urban planning and design, urban environment visualization, promotion and learning of urban information, 2) specific urban planning, 3) those usages that are not directly related either to planning, or to visualization, for example, city population estimation as an operational procedure "on fly", that can be completed on any date between census, 4) commercial sector and marketing, including infrastructure, facility services related to specific urban information visualization, and urban data mining.

The range of those industrial applications that are pertinent, for example, only to *BE* and *BERA* building extraction functionalities may be lengthy enough: urban and municipal planning, augmented reality for gaming industries; environmental planning and monitoring, insurance policy and procedures, optimization of transmitter placement for telecommunication, locational based services, navigation, housing simulations, urban microclimate investigations, and shadow estimation. In all these use cases a building model is the primary object of interest, while exactly the sets of these models examined within the frameworks of the urbogeosystemic approach can, in our opinion, act as those elementary functional constituents of the actual city environment, which compose its *adaptive renewal cycle* with all four basic functions: *exploiting*, *conserving*, *releasing*, and *recognizing* [44]. These functions can be efficiently defined with the UGS approach, if we consider urban (agglomeration) growth in the context of this cycle, while also applying to spatial morphology, as those authors to whom we have just referred to, suggested once.

The point of view introduced in the above paragraph can be accepted as a forcible argument for choosing exactly *a set-of modeled buildings-level* for an urban population estimation use-case as a dominant one in a perspective of that agglomeration research, to which the UGS approach could mostly contribute. If an urban agglomeration is "…the future spatial organization of cities" [8], then any proven method of robust estimation of the population on the base of the urban spatial morphology are expected to be valuable enough.

Taking into account the routine public scarcity of real population values in various city district configurations of a real city, any more or less reliable procedures for evaluating numbers of residents between two censuses, which temporal gap may be up to ten and even more years, can hardly be overvalued [39]. Therefore, even an approximate estimation within a certain selected AOI may be highly necessary for optimizing routine municipal management. It has been evidently proved by the latest events in urban areas due to the modern pandemic phenomenon.

If we accept both separate buildings, and the sets of them as elementary functional urbogeosystemic units within a certain geographical extent of a city, then it is evident that not only different linkages caused by people movement between these sets combined in modeled city districts should be taken into account for calculating a number of residents in a certain area-of-interest (AOI), but also – building geometries themselves. The latter parameters can be the most precisely reconstructed just by LiDAR data processing, which proves the applicability of our approach to agglomeration research in overall extent. The UGS approach to population estimation has been supplemented by some existing methods of GIS /urban remote sensing application within this use case. This GIS/URS application is mainly concerned with the urban block- and census track-level of a number of residents calculating [45–48].

In one of our former publications, we have already presented "the step-by-step building space-metric method (BSMM) of population estimation" [39]. This method presents the series of procedures for any AOI, block, and district population estimations based on the building geometric and city space topological parameters derived from airborne LiDAR data processing. As it has been stated in the second section of this chapter, **Figure 1** summarized our whole research workflow, in which the BSMM was accomplished within three following consequent blocks: 1) *A Human Geography model…= >* 2) *A GIS-model of an UGS = >* 3) *Emergent properties of an internal UGS (interdependencies among city districts in an internal urbogeosystem)*. The blocks *Urban LiDAR data* and *Available attribute data for a city* were completed even before this BSMM block-trinity 1)-3), and their output was transferred through the first and the second summarizing nodes to *A GIS-model of a UGS* block (**Figure 1**). *Point-*, *Linear-*, and *Areal GIS feature* blocks are locked to the second block of the mentioned trinity. A whole introduced configuration of blocks is based on building a model produced by two blocks: 1) *A Human Geography model…= >* 2) *A GIS-model of a UGS*. This model is used for the calculation of interactions due to people movement among city districts and *census tracks* in the internal UGS. Geoprocessing aspect of the methodology introduced in this paragraph consists in adding population data to the metadata of. O*BJ* files presenting building models, and then visualizing in a *Cesium Scene* by the gradient color method.

A study area and data sources are related to the city of Boston, Massachusetts state, USA, and overlapped most of this urban territory. While completing the *ELiT* Geoportal web resource [39], we applied to airborne LiDAR data of open access as to one of the USGS projects available from: ftp://rockyftp.cr.usgs.gov/vdelivery/ Datasets/Staged/Elevation/LPC/Projects/USGS\_LPC\_MA\_Sndy\_CMPG\_2013\_ LAS\_2015/laz/. The relevant census data were available from the U.S. Census Bureau's Web site (http://data.census.gov/), and from the Bureau of Geographic Information (MassGIS) site – the regional data of the 2010 U.S. Census [49]. A seamless, Massachusetts statewide digital map of land use has been taken from [50]. We assumed that it would be possible to obtain the territorial distribution of the population from UGS elementary functional units – the building models and *their affiliated volumes.* The BFT- parameter – Building Function Type (first of all – *residential, non-residential*) has been used as a key semantic attribute. Because of the lack of reliable semantic data and a certain vagueness of a particular building belonging to a certain land-use class, we had to apply to the original technique of automated definition of building type by its topology and geometry [39]. In total, the following stages complete the whole URS/GIS-tools pipeline of population estimation within the urbogeosystemic approach with BSMM:

1.*The preliminary data preparation stage* for population estimation on the basis of the UGS approach with LiDAR data processing was like follows. LiDAR point clouds as *\**.*LAZ* files were downloaded from a few USGS projects through the web reference mentioned above. Building footprints were downloaded from the Open Street Maps (OSM) resource https://developer.here.com/products/ data-layers?cid=. All footprints were combined in a united*.SHP* file by the *Save as =>*. S*HP* tool, which can be applied for any vector layer in the *QGIS 3.10* GIS platform. This combined file might contain information about 1) building population counts, and about 2) classes of buildings (a class of residential ones and a few classes of non-residential buildings – commercial, industrial, educational). This information can be available from the OSM footprints, but footprints with it overlapped not more, than 5% of their total number only.

Thus we have to apply to alternative information sources from [49, 50], as we have already mentioned above. Thus, after completing the preliminary stage of the population estimation use case we obtain the following:


In the same way as on the visual above, a layer of building models has been placed on the census parcels.


#### **Figure 6.**

*Visualized in the QGIS-interface the points of building models (footprint centroids) located through different classes of land use in a fragment of the urbanized territory of Boston. The complete land use legend is available from [50].*

area. A procedure is completed with the *SAGA= > Add polygon attributes to points* tool. A new file in the point layer attribute table is titled in the same way with the attribute table of the census parcel layer - *"POP100\_RE"*.


*Urbogeosystemic Approach to Agglomeration Study within the Urban Remote Sensing Frameworks DOI: http://dx.doi.org/10.5772/intechopen.102482*

#### **Figure 7.**

*Resulted from the URS/GIS pipeline stages 1–4 visualization of the building population distribution in the urbanistic environment of Boston-City presented in a 3D scene of the ELiT cloud processing platform interface.*

*bldng\_popul* = *(volume\*POP100\_RE\*COEF/SUM\_volume*, where *volume –* a building volume, *POP100\_RE* – a population value for a given census track, in which this building falls in; *SUM\_volume* – a total volume of building in a census parcel.


While implementing a population estimation use case, it is reasonable to take into account, that some computed extreme numbers of residents can be caused by the errors in the input land use data. For example, a large residential building has been prescribed to the commercial or to any other non-residential class of land-use, while being actually in one census parcel with another, much smaller residential building, and there are only two these buildings in a given parcel. The small building, being prescribed to the residential class properly, has accepted a whole number of residents in a parcel, and a number of residents is drastically exaggerated then.

#### **5. Conclusions**

This chapter has introduced the original conceptual research approach concerning the urban geographical system, which is based on urban remote sensing with LiDAR data processing. The authors have made an attempt to prove that the presented methodology and techniques might contribute to the scientific understanding of the urban agglomeration as a highly developed spatial aggregation of urbanized areas. The urbanistic environment as a quasi-rasterized 3D model of actual city space, and the urbogeosystem as a quasi-vector 3D model of the hierarchical formalized aggregate of UGS elementary functional units – buildings, both can efficiently simulate, visualize, and represent an urban agglomeration according to its all representative criteria. The algorithmic flowchart of the UGS study within the suggested approach has been provided, and further research introduction has been affiliated with flowchart blocks.

The URS/GIS pipeline of making a digital city with LiDAR data processing has been examined mainly within an automated feature extraction perspective. In particular, it has been illustrated by the AFE-flowchart of some key processing constituents related generation of both urban topography, and building models from LiDAR point clouds. The possible scheme of digital city creation might consist of two consequent steps: 1) modeling the quasi-rasterized UE, and 2) simulating the quasi-vector UGS.

Web-based geoinformation software for LiDAR data processing due to the objectives of urban studies, in general, and agglomeration research, in particular, should demonstrate its optimal architectural solution as both a client–server application, and as a cloud-processing platform. The latter applies to AWS resources. HPM-technique provided by this software is preferable for the urbanistic environment modeling, while its LPM-method – for model generation of elementary functional units of the UGS – buildings. Each one from the row of software tools – *BE*, *BERA*, *CD*, and *DEM-G* can contribute in a particular perspective to agglomeration research.

Mentioning several thematic applications, which can potentially be resolved within the frameworks of the presented approach, we selected and examined in detail the building population estimation use case as the most relevant one to agglomeration research. A number of building residents, as a rule, are not widely available due to security and privacy reason. Thus, the suggested technique can significantly assist not only in an AOI-population estimation between census but also, e.g., in predicting the agglomeration growth in both short-term and long-term perspectives.

#### **Appendices**


*Urbogeosystemic Approach to Agglomeration Study within the Urban Remote Sensing Frameworks DOI: http://dx.doi.org/10.5772/intechopen.102482*


#### **Author details**

Sergiy Kostrikov and Denis Seryogin\* V.N. Karazin Kharkiv National University, Kharkiv, Ukraine

\*Address all correspondence to: sergiy.kostrikov@karazin.ua

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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## *Edited by Alessandra Battisti and Serena Baiani*

Due to climatic, social, and epidemiological challenges, urban areas are suffering from recurring problems that require profound and sustainable solutions. Although they cover only a small area of the earth's surface, metropolises are responsible for most of the world's global carbon emissions, which cause adverse effects on energy and the climate. This book discusses the spatial development of urban areas in the context of the United Nations Sustainable Development Goals. Chapters address the problems of large urban agglomerations, examine their impacts on both people and the environment, and propose intervention policies and strategies. The book also presents case studies from different areas of the world, including Chile, Brazil, and India.

Published in London, UK © 2022 IntechOpen © Naeblys / iStock

Sustainable Development Dimensions and Urban Agglomeration

Sustainable Development

Dimensions and Urban

Agglomeration

*Edited by Alessandra Battisti and Serena Baiani*