A Prototype of Energy Efficient Houses Meeting Both Bioclimatic Architecture Principles and Moroccan Thermal Regulation

*Khalid El Harrouni, Najma Laaroussi, Najoua Loudyi, Rime El Harrouni, Hajar Amir and Ricardo Castello* 

### **Abstract**

 The building sector is an activity where the potential for saving energy is important and Morocco is now placing the housing sector energy efficiency and renewable energies among the national priorities in order to reduce the energy consumption and improve the thermal comfort. As part of the national energy strategy, several actions have been initiated, the code energy efficiency in the building, including the thermal regulation of construction setting the energy performance rules for buildings. This chapter presents the good practices for the control of the energy by using the principles of the bioclimatic architecture, and by adopting the passive and active energy efficiency for two house building case studies (villa in Marrakech and modern Moroccan house in Midelt), both situated in severe climate conditions. The approach method analysis covers three thematic subjects: (1) the architecture and building relationship with the climate; (2) the usage and the thermal comfort; (3) the energy management and the performance according to the Moroccan thermal regulation. Investigation and methodological tools were based on the documentation, numerical modeling (Cypetherm Eplus by CYPE), plans, photos, and surveys (architects and occupants). The process is then described from design to completion, with its techniques, materials, and learned lessons.

**Keywords:** bioclimatic architecture, energy efficiency, thermal regulation, pilot house buildings, CYPE

#### **1. Introduction**

Morocco is experiencing strong economic and social growth resulting in accelerated energy needs. In order to combine security of supply and reduction of dependence on energy, environmental preservation, reduction of energy consumption, and thermal comfort, Morocco has developed a new energy strategy based, first of all, on the following orientations:

• An optimized and diversified energy mix around competitive and reliable technological choices.


This strategy promotes, among other things, the development of renewable energies and energy efficiency in urban planning, housing, and building design. Indeed, over the last 10 years, Morocco has recorded an average growth rate of 4.2%. The construction and the public work sector have experienced particularly exceptional progress, aiming at filling the delays and deficits recorded in the areas of housing, equipment, and infrastructures. Work sites are open in all regions of the country to meet the needs of a growing population and a great increase in the urbanization rate which reached more than 60% (according to the *General Census of Population and Housing* RGPH 2014), against 55% in 2004.

A figure to remember: in 2014, the national housing rate amounted to 8.9 million housing units, 6.2 million of which are in urban areas (70%) and 2.7 million in rural areas (30%). Even though apartments have been produced in significant quantities, the Moroccan house accounts for 67% of the park in urban areas.

According to the summary of the results of the Housing Survey [1], the annual rate of production of housing is in recent years around 150,000 homes per year, on average, at the national level. About 2.1 million dwellings are to be produced over 10 years with an average annual production of 214,000 dwellings. Finally, the results of such an investigation show that most of the housing needs effort at the national level is to be focused on social and economic housing in all the regions and the cities.

On the basis of this observation, several national programs have been put in place, notably the intensification of supply in lots and housing (more than 150,000 units produced per year); the diversification of housing products for the middle class; the promotion of the social housing; the opening of new Urbanization Zones (ZUN); the creation of new cities and large urban complexes; the urban upgrading of cities aimed at requalification; and urban renewal.

 However, the building sector in Morocco is particularly a large consumer of energy, estimated at 25% of total energy, including nearly 18% in residential and 7% in the tertiary sector. In addition, Morocco has to import almost all of its energy needs, mainly fuel, which heavily bears the weight of the energy bill. Faced with this situation, Morocco is now placing the housing sector and energy efficiency and renewable energies among the national priorities; these two sectors are expected to develop a strong synergy. The issue of sustainable buildings, cities, and territories is at the heart of public policy and is a major topic for the years to come, and a challenge for architectural and urban practices, which over the past 20 years have evolved rapidly to take into account, in particular, the principles associated with sustainable development. These new ways of designing and developing the space are aimed at reducing energy consumption, limiting CO2 emissions, improving user comfort, offering more environmentally-friendly ways of developing, and offering sustainable solutions to urban problems.

As part of the national energy strategy, several actions have been initiated, including the Law on Energy Efficiency (N° 47-09); the Law on Renewable Energies (N° 13-09); the Law N° 58-15 modifying and completing the Law N° 13-09 relating to renewable energies; the adoption of Law 48-15 on the regularization of the energy sector and implementation of the National Electricity Regulatory Authority responsible for access and use of the medium and high voltage network for new

*A Prototype of Energy Efficient Houses Meeting Both Bioclimatic Architecture Principles… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

producers. The publication of this Law in 2016 represented an important step toward the liberalization of the electricity sector.

Other actions were related to:


 This chapter presents the good practice of the control of the energy and the climate at the scale of the city and the habitat by using the principles of the passive architecture, solar architecture and bioclimatic architecture, and by adopting the passive and active energy efficiency for two house building case studies: a villa in Marrakech city and a modern Moroccan house in Midelt city, both situated in severe climate conditions, very cold in winter and very hot in summer.

The chapter is from the work carried out related to the development of the catalog of pilot building cases integrating renewable energies and energy efficiency, titled "Architecture and Energy Efficiency: 10 case studies of good practices in Morocco," as part of the Deutsche Klima—und project—Initiative Technology, supported by GIZ and elaborated by a team from the Ecole Nationale d'Architecture de Rabat [3]. The work is also part of the research project "Solar Bioclimatic Architecture and Energy Efficiency in the Building," financed by the Moroccan Ministry of Higher Education and Scientific Research, CNRST, within the framework of the call for projects in the priorities for scientific research and technological development.

The approach method analysis covers three thematic subjects:


#### **2. Climate and building description**

#### **2.1 Climate description**

In order to identify good practice of energy control through the bioclimatic architecture principles both in terms of the city and the habitat scale, two case studies are selected: a villa in Marrakech city and a modern Moroccan house in Midelt city, both present severe climate conditions.

 Some climate data are shown in **Figure 1** for the extreme climate conditions: hot climate in Marrakech agglomeration where the highest average maximum temperature is reached during July, of about 39°C, and cold and dry climate in Midelt where the average minimal temperature occurs during January (0°C), while the average relative humidity ranges between 25 and 50%. During February and December in Midelt, the average minimum air temperature approaches 2°C, and the coldest months are January, February, and December.

According to the Thermal Regulation of Construction in Morocco, **Figure 2**  shows the climate zoning including six climate zones, and **Table 1** gives the thermal zone and the energy demand allowed for heating and cooling residential buildings situated in the two cities.

#### **2.2 Building description**

The two residential buildings investigated in this chapter are: a villa type one in Marrakech and a typical residential building in Midelt. This chapter attempts to analyze the building envelopes as shown in **Figures 3** and **4**. The compositions of the envelope building elements including walls and roof, and their thermal properties [5] are given in **Tables 2**–**5**.




#### **Figure 1.**

*Marrakech and Midelt climate data.* 

*A Prototype of Energy Efficient Houses Meeting Both Bioclimatic Architecture Principles… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

#### **Figure 2.**  *Moroccan climate zoning [2].*


#### **Table 1.**

*Climate site characteristics [2].* 

**Figure 3.**  *A villa type in Marrakech.* 

#### **Figure 4.**

*A typical residential building in Midelt.* 


#### **Table 2.**

*External walls of the villa in Marrakech [5].* 


#### **Table 3.**

*Roof of the villa in Marrakech [5].* 


*A Prototype of Energy Efficient Houses Meeting Both Bioclimatic Architecture Principles… DOI: http://dx.doi.org/10.5772/intechopen.87836* 


**Table 4.** 

*External walls of the typical residential building in Midelt [5].* 


**Table 5.** 

*Roof of the typical residential building in Midelt [5].* 

#### **3. Key features**

#### **3.1 The building envelope**

Building envelope constitutes a protective barrier and a construction measure to achieve energy efficiency and an indoor comfort. Thus, proper design of the building envelope is a major factor that influences directly the energy consumption and interior comfort as well as the components of walls and roof. These parameters affect the heat transfer coefficient (U-value) of the building.

Regarding the Thermal Regulation on Moroccan Construction (RTCM), it is only regulation addressing the energetic performance issues, and the maximum heat transmittance coefficient (U-value) of walls, windows, roofs, and floors in the climate zones is given. **Table 6** shows the comparison between the calculated U-value for the two envelope buildings and the transmittance requirements in climate zones 4 (Midelt) and 5 (Marrakech).

The U-values of the walls, roofs, and the windows glazing are 0.45, 0.44, and 2.87 W/m2 K, respectively, for the typical residential building located in Midelt. The U-values of the walls, roofs, and the windows glazing are 0.24, 0.38, and 2.50 W/m2 K, respectively, for the villa situated in Marrakech.

#### **3.2 Thermal comfort**

The essential design parameters, which affects energy conservation and indoor thermal comfort in building scale, are building envelope design, building materials,


#### **Table 6.**

*Comparison between the calculated U-value and the transmittance requirements.* 

building form and layout, and optical and thermo-physical properties of the building envelope. Building envelope design, as it separates the outdoor and indoor environment, is the most important parameter among the others.

 Provision for dwellers comfort and suitable interior temperatures should be considered. For passive comfort of the villa in Marrakech and according to some measured temperatures [6] during winter season, while the outside temperature ranged between 7 and 23°C, the temperature interior of the villa (doors, windows and shutters closed) was very stable at 18 ± 0.5°C. The opening of the shutters during the day allowed to gain 1 to 2°C more. During summer season, the house is completely closed (shutters included); while the outside temperature ranged between 23 and 41°C, the temperature was very stable at 28.3 ± 0.3°C ground floor and 29.6 ± 0.3°C upstairs.

Regarding the typical residential building located in Midelt, **Figures 5** and **6**  show the hourly variation of the temperature throughout the year and the comparison of the outdoor and indoor temperatures for both cases, with and without the thermal insulation of the building envelope.

#### **3.3 Bioclimatic analysis**

In the literature, there are several tools noted to analyze climate conditions, including the Szokolay Bioclimatic chart, the Olgyay Bioclimatic chart, the Mahoney table, and the Givoni Bioclimatic chart.

The Olgyay Bioclimatic chart [7] is one of the tools widely employed by an architect in the predesign stage of building design. Historical data related to relative humidity and temperature are plotted in the chart at this stage. The comfort zone is shown at the center of Olgyay's chart which has a constant comfort in the range from 20 to 30°C (**Figure 7**). Corrective measures needed for factors, such as radian temperature, wind speed, shading, and solar radiation, can also be known for every plotted fall over the comfort zone. Since Olgyay's chart only considers the outdoor conditions disregarding the indoors physiological considerations, it is only applicable for hot humid climates where there is minimal fluctuation between the indoor and the outdoor temperatures [8].

The Givoni and Szokolay Bioclimatic charts [9, 10] are mainly applied for residential-scale construction, and they provide more alternatives with building design to enable thermal comfort, including natural ventilation, evaporative cooling, dehumidification, thermal mass, conventional air conditioning, or passive heating.

*A Prototype of Energy Efficient Houses Meeting Both Bioclimatic Architecture Principles… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

**Figure 5.** 

*Indoor temperature variation of the building with the thermal insulation, Midelt.* 

#### **Figure 6.**

*Indoor temperature variation of the building without the thermal insulation, Midelt.* 

**Figure 7.**  *Olgyay bioclimatic chart.* 

According to the Mahoney table [11], temperature, relative humidity, and precipitation/rainfall constitute the elements for climate analysis that determine the design recommendations (building envelope, openings, spacing, layout, and air movement).

All of these tools have been used in this chapter to investigate appropriate design recommendations for the two different climates by analyzing the climatic characteristics of the selected cities, Marrakech and Midelt. These three tools are well known and are believed to be appropriate tools for the investigation of a strategy for designing buildings that correspond to the climate. Some passive design strategies were proposed based on the bioclimatic analysis.

According to the Midelt Givoni/Szokolay bioclimatic diagrams, it is recommended to have high thermal inertia during the summer season. The diagram also shows that one can obtain a comfortable indoor climate using passive heating through internal gains during the months of October, April, and May. The active heating should be used for the winter season and quite cold months like November and March.

For Marrakech, it is recommended to use natural ventilation with dehumidification, especially for the month of September and to have high thermal inertia with night ventilation during the summer season although the buildings must be designed with good ventilation possibilities and protection against solar radiation. A comfortable indoor climate can be obtained using passive heating through internal gains during fairly cold months.

Based on a diagnosis of some climatic indicators, the Mahoney table analysis gives the performance specifications and the design recommendation for buildings in Marrakech and Midelt in order to have a best indoor climate, as shown in **Table 7**.

#### **3.4 Building orientation and openings (windows)**

In order to avoid high solar penetration coming from the east in the morning and the west in the evening, the optimal orientation recommended by the Mahoney table is north south. Nevertheless, the surrounding environment remains a parameter that limits this orientation choice.

Regarding the case of Marrakech, the south facing walls of the villa present a significant glazed area, especially in the first floor. The villa has a maximum on the south facade, a minimum on the façade west, and a moderate number on the east and north facades (summer ventilation). A shading device overhangs the south facade of the second floor. This device was designed to completely shadow the glazed French windows in the summer solstice, while these glazed areas are completely sunlit in the winter solstice [4].

 Windows are essential parts of the building envelope. They have significant effect on the thermal comfort and energy performance so that they must be chosen with care. Windows are the main source of thermal losses to the exterior and solar gains to the interior within building envelopes. The double-glazed windows with a layer of air or inert gas between each pane provide more thermal resistance in cold (Midelt) and hot (Marrakech) climates: 6/6/6 and 6/10/6 yield to U-value of 2.9 and 2.5 W/m2 K, respectively.

#### **3.5 Walls and roofs**

Stone, brick, concrete, hollow clay tile, tile, gypsum, concrete brick, and other materials combined and set into close positioning with mortar constitute the masonry mode of construction. By introducing insulation materials (in the form of


**Table 7.** 

*Design recommendation from Mahoney table.* 

*A Prototype of Energy Efficient Houses Meeting Both Bioclimatic Architecture Principles… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

a sandwich), the energy consumption is then reduced through the building envelope. Wool, polyurethane, or polystyrene are the most suitable insulating materials as shown in both studied cases as they afford the possibility to reach between 20 and 66% of energy economy.

Heavy walls and roofs will help to protect the building from heating from solar penetration. Thus, as discussed previously, the occupancy schedule should be a factor of concern in choosing the walls and roofs design, especially in relation to the time lag of reradiating the heat from the building materials.

 As the Mahoney table proposed a heavy wall with a high thermal mass, the Szokolay/Givoni bioclimatic charts recommended a high thermal mass material as the passive strategy. Furthermore, the thermal simulations confirmed the use of heavy weight wall as a best way to be applied in Marrakech and Midelt.

One important issue related to the hot climate, in Marrakech for example, is that the soil at great depth is near 19.5°C. This situation is profitable for isolating the building envelope except at the footprint, so that will control the temperature of the whole house. Interior walls of the ground floor should be massive to improve the transfer of soil to the whole building.

#### **3.6 Insulation impact on the energy loads**

**Table 8** shows the impact of the walls/roofs/windows insulation on the energy load for both buildings in Marrakech and Midelt. It gives the comparison of cooling/ heating loads, before and after insulation using different modeling tools and finally the total is compared to the maximum Energy demand allowed by the Thermal Regulation of Construction in Morocco for heating and cooling (kWh/m<sup>2</sup> /year).

 Regarding the example of the villa in Marrakech without insulation, the energy load during winter is close to 40 kWh/m2 heating to maintain 20°C continuously. In summer, to maintain 26°C, it is almost 65 kWh/m2 , a total of about 105 kWh/year/m2 of living space (results obtained using TRNSYS, Transient system simulation tool). Cooling/ heating loads of the same building with insulation of walls, roofs and, windows have been estimated: in winter, 15 kWh/m2 of heating is enough to maintain 20°C continuously. In summer, it does not need more than 23 kWh/m2 to maintain 26°C. A total of about 38 kWh/year/m2 represents almost one-third of the consumed energy without insulation.


#### **Table 8.**

*Comparison of insulation impact on the energy loads.* 

For the typical residential building located in Midelt under the same indoor temperature conditions in winter (20°C) and summer (26°C), the total of cooling and heating loads without insulation is estimated to 82.5 kWh/m2 (78.0 kWh/m2 using DesignBuilder tool) against 59.20 kWh/m2 with insulation (61.1 kWh/m2 using DesignBuilder tool). These results are obtained using Cypetherm Eplus by CYPE (Software for Architecture, Engineering and Construction).

#### **4. Conclusion**

The chapter examined thermal performance of two pilot buildings, situated in two extreme climate conditions in Morocco, and it showed the bioclimatic approach in building design as well as the techniques which have been applied to formulate various strategies in order to achieve indoor comfort conditions and to reduce the heating and cooling energy consumption.

The most appropriate design strategies for cold and hot regions were deduced. The following findings are drawn based on the results obtained from the bioclimatic analysis and energy simulation using different modeling tools (TRNSYS, DesignBuilder and Cypetherm Eplus by CYPE).

The two houses are made by bioclimatic principles, mainly the building orientation, and compacity and equipped according to the latest environmental standards and requirements according to the Moroccan thermal regulation. There are also some passive strategies that are proposed by the bioclimatic analysis. One of the strategies is the roof and wall materials. The largest part of the building envelope is the walls; hence, using appropriate wall material should largely affect the indoor thermal conditions.

 Envelope insulation, including the walls, the roofs, and the windows glazing, has significant impact on total energy consumption and the indoor thermal comfort. The external walls as well as the windows and roofs should be then insulated.

#### **Author details**

Khalid El Harrouni1 \*, Najma Laaroussi<sup>2</sup> , Najoua Loudyi1 , Rime El Harrouni1 , Hajar Amir3 and Ricardo Castello3

1 National School of Architecture, Rabat, Morocco

2 Mohammed V University, Rabat, Morocco

3 CYPE Software for Architecture, Engineering and Construction, Casablanca, Morocco

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

© 2019 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.

*A Prototype of Energy Efficient Houses Meeting Both Bioclimatic Architecture Principles… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

#### **References**

[1] Kingdom of Morocco. Ministry of Housing and Urban Policy, Housing Survey 2012, Phase IV: Synthesis of Housing Survey Results, Interpretation and Development of a Housing Methodology Needs and Assessment. Marsult Info/UPEA; 2015 (in French)

[2] Royaume du Maroc. General Construction Regulation fixing the energy performance of buildings, Decree No. 2-13-874 of October 15, 2014, published in Official Bulletin no. 6306. 2014. pp. 4256-4269 (in French)

[3] Mansour M, El Harrouni K, Radoine H. Architecture and Energy Efficiency: Ten Case Studies of Good Practices in Morocco. Rabat, GIZ Maroc: Nationale School of Architecture; 2016 (in French)

[4] CYPETHERM EPlus. Modelling and energy simulation of buildings with EnergyPlus™, integrated in the Open BIM workflow via IFC and gbXML. Available from: http:// cypetherm-suite.en.cype.com/ [Accessed: 01 February 2019]

[5] Benhamou B, Bennouna A. Energy performance of a passive building in Marrakech: Parametric study. Energy Procedia. 2013;**42**:624-632

[6] Khabbaz M, Benhamou B, Limam K, Hollmuller P, Hamdi H, Bennouna A. Experimental and numerical study of an earth-to-air heat exchanger for air cooling in a residential building in hot semi-arid climate. Energy and Buildings. 2016;**125**:109-121

 [7] Olgyay V. Design with Climate, Bioclimatic Approach and Architectural Regionalism. New and expanded edition, 2015. New Jersey: Princeton University Press; 1963

[8] Sayigh A, Marafia AH. Thermal comfort and the development of

bioclimatic concept in building design. Renewable and Sustainable Energy Reviews. 1998;**2**:3-24

[9] Givoni B. Climate Considerations in Building and Urban Design. Toronto, Canada: John Wiley & Sons; 1998

[10] Szokolay SV. Heating and cooling of buildings, chap. 20. In: Cowan HJ, editor. Handbook of Architectural Technology. New York: Van Nostrand Reinhold; 1991

[11] Sealey A. Introduction to building climatology—Chapter 10—The Mahoney Tables.pdf. In: Introduction to Building Climatology. London, UK: Commonwealth Association of Architects. p. 1979

**39**

**Chapter 4**

**Abstract**

**1. Introduction**

"abstraction of a good design in nature."

Biomimicry for Sustainability:

Improvement of Building Skin

*Güneş Mutlu Avinç and Semra Arslan Selçuk*

use that can be seen as the most vital sustainable design criteria.

**Keywords:** sustainability, biomimicry, bio-skin, building envelope, facade

Although it is as old as human history, scientific conceptualization of the biomimetic approach began in the twentieth century. Biomimetics having been constructed on natural references is leading the development of many innovative ideas and practices in the field of architecture. Biomimicry imitates the forms, systems, and processes found in nature to solve the most important problems our world is facing and to produce sustainable solutions [1]. Vincent [2] defines this approach as

So far it is observed that the biomimicry has potentials for sustainability and energy issues, particularly in the design and construction field [1]. With this approach, the deepening nature of perception provides new perspectives on the development of sustainable approaches to the scientists who are conducting research in the field of architecture. Thus, these developed sustainable approaches are included in the literature as a product of interdisciplinary studies, especially

with Nature-Inspired Innovations

Energy efficiency and related concepts of it for sustainability in architecture are the important issues of the twenty-first century architecture and "nature" has prospective ideas in terms of sustainable design. Buildings can be designed, constructed, and operated in a "holistic approach" according to the principles extracted from nature. Thus, "innovative design approaches learned from nature" is one of the most important architectural manifestos of today. This chapter focuses on the intersection of "biomimicry" and "building envelope" to discuss the skin/skin functions of organisms in nature and biomimetic design approaches in building shells as an energy management instrument. In order to examine how different skin/shell functions in nature have been transferred to the building shell, the pioneering studies in the literature have been examined and a comparison has been done to figure out functional similarities between skin of the natural organisms and the building facades. Selected studies are conceptual or applied projects and designs that are inspired/learned from different natural skin or surface characteristics in different climate regions. As a result of the evaluation, biomimetic building shell designs have been found to provide energy and resource efficiency without active energy

#### **Chapter 4**
