**2. Urban pattern configuration and sustainability**

Like old Islamic Arab cities, the urban pattern of historic Jeddah, is characterized by its organic open space system (**Figure 2**). This urban pattern has emerged with

**Figure 2.** *Building forms in historic Jeddah.*

**Figure 3.** *Map of historic Jeddah showing its organic open space system [7].*

intended control over the microclimate of the area. Responding to the hot-humid climate, open space system adopted a network of narrow paths "*harat*" leading into intimate open spaces "*barhat*" [6]. While, buildings are intense, converge and adjacent (**Figure 3**). Paths vary from main or major (12–20 m), primary or local (4–10 m), and secondary (2–4 m). With a height of two to five storeys, building heights range between 8 and 20 m. Width to height aspect ratios are thus in the range of 1/2 and 1/5 or narrower in many cases (**Figure 4**).

This compact configuration of the urban tissue could adequately protect the buildings and the open spaces from the harsh weather by offering abundant areas of shade and shadows. Yet, complete shade was intentionally avoided. For outdoor spaces to be healthy, paths are exposed to sunlight for a short time, while the open spaces are receiving it for longer times along the day. The best-known benefit of sunlight is its ability to enhance providing the body with vitamin D. A half-hour in the sun can initiate enough amount for a whole day. But, most public health messages have focused on the hazards of too much sun exposure where it can contribute to sunburn or skin diseases [8].

However, open spaces will receive more intense solar radiation causing their contents to be heater than the shaded paths. Then, the hot and less dense air creates a dynamic thermal system motivated by the cooler and more dense air. Cool air masses accordingly flow from the narrow paths to replace the hot air with different velocities that help to alleviate the air temperature and the impact of humidity [9]. Narrowing paths cross-section contributes accelerating the air currents. Simulation with ANSYS R19.2 software accords with the phenomenon (**Figure 5**). Compared with modern streets, air temperature of Jeddah traditional open spaces is found to be cooler by more than 3°C, especially during peak heat hours [10]. Moreover, buildings are mostly configured with spaces in between to facilitate the movement of air around them.

Path orientation plays another role in influencing local climate. Relatively speaking, the urban tissue is configured taking the shape of stripes. Some of them are perpendicular to the coast allowing the sea breeze to smoothly penetrate through buildings, while the others are aligned with the north–south direction perpendicular to the path of sun which keeps their paths in shade most of the day and eases channeling airflow smoothly into the city's fabric.

**Figure 4.** *Paths with different aspect ratios.*

*Sustainability Features of Jeddah Traditional Housing DOI: http://dx.doi.org/10.5772/intechopen.98735*

The effect of path orientation and its aspect ratio on reducing the impact of the local climate was investigated by ENVI-met, a computer simulations software (**Figure 6**). The results show that streets with higher aspect ratio (1/2.5) have better outdoor thermal comfort conditions than the ones with lower aspect ratio (1/0.5). Due to more urban shading that the buildings create, temperature can be decreased to 22°C in PET index. The preferable order of street orientations was found to be

#### **Figure 5.**

*Wind velocity in the open spaces of historic Jeddah.*

**Figure 6.** *Examined paths H/W aspect ratio.*

N-S, NW-SE, E-W and NE–SW. Also, increasing the aspect ratio reduces, to varying degrees, the air temperature (up to 1.7°C), mean radiant temperature (up to 33° C), the wind velocity while increasing the relative humidity (up to 5%) [11]. However, decrease in wind velocity does deny its existence. To great extent, results

are in line with the conditions in historic Jeddah. The urban pattern of historical Jeddah did not handle with the environmental framework only. With the same efficiency, the urban pattern maintained social and

**Figure 7.** *Vitality of main paths and open spaces maintained by walkability.*

**Figure 8.** *The axial map of historic Jeddah produced by integration-Rn.*

*Sustainability Features of Jeddah Traditional Housing DOI: http://dx.doi.org/10.5772/intechopen.98735*

economic sides of sustainability. The hierarchical and compact open spaces system provided different levels of spaces ranging from public, semi-private to private. Each level of the spaces promoted different form of social relationship among residents. Small open spaces and secondary paths were used as playing areas for children to have fun under the supervision of mothers who manage to assemble and chat around. In larger scale spaces, men settlers of adjacent houses sit in groups on raised floor. Also, in these spaces sons can safely play overseen by fathers. Moreover, allocating shops integrated with the residential use on main paths and open spaces, as well as communal services like masjids, enabled inhabitants to move easily in between. This approach, known as mixed uses, encourages walkability, ensures safety and natural surveillance and supports commercial vitality (**Figure 7**).

A Space Syntax study attempted to understand the effect of spatial configuration on movement patterns (**Figure 8**). Outcomes of the study illustrate that the total pedestrian density and the Intensity of moving people are concentrated on the major paths (red-orange in the figure), followed by the local paths (yellow-green lines), and then by the secondary paths (blue lines). This explains the appropriateness of each segment for the intended function i.e., privacy and safety for women and children, controlled openness for men and vitality for commercial movement [12].

### **3. House design and sustainability**

Like the urban pattern, sustainability with its integrated concept has been considered in the historic house of Jeddah too. It was shaped to meet local traditions, local climate and economic abilities. The well-established social traditions dictated the separation of private and public life which was reflected on allocating spaces in the house. There is a spacious zone at the entrance "*salamlek*", which is donated to men settlers where strangers are received. While, the other section of the house "*haramlek*" is dedicated to women and their life to provide maximum protection from the eyes of strangers. This however produced a dual system of movement to allow using private and public spaces severally [13].

On the ground floor, the house has its bigger rooms, such as reception room "*dehleez*" and the guest room "*majlis*", in the front section (**Figure 9**). These rooms are generally higher than others and the floors are kept wet to maintain them cool in hot days. Houses on main paths contain shops, storage rooms and warehouses, each has separate entrances from the path and not connected to the rest of the house.

Other facilities, such as the staircase "*daraj*", the kitchen, storage areas, toilets as well as sleeping rooms share the rear part of the house. Number of rooms in the house varies according to the ability of the residents. However, the house usually has two entry points. The main entrance is placed on street preceded by a number of steps and mostly used for men. On one of the other sides, another entrance for women and family members is located. The family entrance leads to the staircase which does not have any visual contact into any room of the house to maintain privacy.

Reception room acts as a transitional zone that links the entrance door and the inner areas of the house. Men gusts may use first floor in special occasions, but upper floors are only confined to family life. Upper floors contain the women guest room which is the largest and most revered space in the house. Its location on the main facade offers the preferable overlook and ventilation provided by large wooden latticed windows "*rawsheen*".

Adjacent to this room, there is a small room known as the "*soffah*" which is used as a living room. A dual-use room, known as the rear "*moakher*", is placed at the

**Figure 9.** *Plans and main elevation of selected historic house.*

**Figure 10.** *Terraces and balustrades details.*

back end of the house. It is a medium- sized room which is used as a sitting room for family women by day, and it turns into a bedroom at night. Hence, the house is inhabited by many extended families; each family has its separate suite.

Whenever the house rises, the floor area of each higher storey retracts creating terraces on the rooftops of annulled rooms. However, terraces provide outdoor spaces for women to perform domestic activities like drying clothes. These terraces are visually protected by heigh balustrades with details that provide privacy but allow air to move through (**Figure 10**). Likewise, the building roof provides other outdoor spaces where inhabitants can use for sitting or sleeping in summer nights. As far as possible, houses are arranged to ensure that an overview of other houses' terraces is prevented according to Islamic sense of propriety.

Almost every house has two to five storeys in a cubical form that does not contain any protrusions, except for the "*rawasheen*". The building form is not

## *Sustainability Features of Jeddah Traditional Housing DOI: http://dx.doi.org/10.5772/intechopen.98735*

straightly configured, but with broken masses so that adequate shade and shadows might be caught.

The direct light hitting the Nawar house and its context could be simulated at different times of the day and year. Results indicate that the direct sunlight during the morning and afternoon hours is largely blocked by the geometry of the house itself, and the neighboring buildings which largely shadow the facades in the lower area of the building (**Figure 11**) [14].

In Jeddah climate, a large amount of air is required to move through the house in order to alleviate the impact of high humidity. Stimulating air to flow requires having a positive pressure side and ensuring that the air outflows from the negative pressure sides carrying humidity and the unpleasant fumes. Therefore, most of the house had two to three facades and arranged to have at least one facade facing the preferred airflow, while others are exposed as possible.

Spaces were arranged so that walls do not obstruct the continuity of air flow by providing openings between the rooms. Openings range between *rawshan* or windows on the main facade, small openings at a heigh level on the opposite walls or integrated on the top of doors. The staircase also helps ventilating the house allowing air currents to vertically flow through running from the ground floor to the roof, which is known as the chimney effect. The staircase shaft also encourages the air circulation between floors.

In the same previous study of Nawar house, the air flow through the house was visualized with the Wind Tunnel Pro simulation software. The visualization of the air flow proves that the wind penetrates through the large *rawshan* in the front facade and continues to drive the air cylinder rotating in the room due to vertical temperature differences. This situation leads to mixing the air layers and intensifies the heat and moisture exchange with the wall and floor surfaces. The small high openings in the wall opposite the *rawshan* facade increase the airflow velocity even more and is literally sucked into outdoor (**Figure 12**).

Beside the role played by the staircase to enhance air movement through the house, some houses were provided with air shafts, a treatment that developed from the traditional wind catcher "*malqaf*" (**Figure 13**). Assessing the impact of air shaft on the relative humidity, air movement, air temperature and the CO2 level -an important indicator of air quality- have been a main interest for some studies.

Two scenarios were monitored in Nassif house "*bait Nassif*". In the first case, the window facing the air shaft was closed; the same window was left opened in the

**Figure 11.** *Nawar house physical model in the light laboratory.*

**Figure 12.**

**Figure 13.** *Air shafts in Nasif house (left: Exterior view) and Nawar house (wright: Interior view).*

second. Results proved the efficiency of thermal performance for the studied space in case of the opened window. Air velocity of 1.1 m/s was achieved in the first case, while it dropped to 0.0 m/s in the second. The average of CO2 which was measured at 395 ppm in the first case opposite to 560 ppm in the second. Relative humidity reduced to 59% while it was 65% with the closed window. Air temperature also dropped from 33°C to 32°C when the window was opened. Comparable results were monitored for Noor Wali house [15].
