**3. Passive cooling actions**

Understanding the sources of heat gains that affect thermal comfort in the building is essential for deciding the type of actions to be taken to avoid as much heat gains as possible, to slow the heating process to remove the uncontrolled gained heat, or to store cold air or elements. The four passive cooling actions include the following:


The four actions of passive cooling, *storing, avoidance*, *slowing*, and *removal*, are discussed in this section in detail with regard to the cooling principles and the designing process, focusing on the variables affecting their performances. Each device or principal will be discussed based on the following categories:


Some passive systems have direct impact on the architecture design, like the design of an opened atrium or a courtyard, and some have less direct influence, like the type of material and use of louvers or shading systems. Therefore, the level of integration between these systems and the architectural elements varies among the different types of systems and actions. However, it is important to understand the requirements of the chosen passive systems and to make the right decisions of when and where to integrate them within the designing process.

#### **3.1 Storing devices**

Storing refers to keep cold air or low temperature object away from direct heat sources to be used to cool down interior spaces. Throughout architectural history, and particularly in hot climate regions, devices were developed for this purpose as storage design elements, like courtyards, earth spaces, basements combined with wind towers, thermal masses, and sunken courtyards. For the purpose of this research, courtyards are discussed as one of the most efficient devices in storing cold objects or air.

### *3.1.1 Courtyard*

Courtyard is an opened space surrounded by rooms with openings on the conjoint wall between the rooms and the courtyard space, to allow air exchange daylight, and view. The courtyard as passive design device works as a modifier of the microclimate and acts as a heat sink and cold air storage. Buildings with internal courtyards are characterized as a suitable solution for cooling in hot climate regions to provide inner spaces with cold air and daylight.

The working mechanism of the courtyard depends on the cycle of day and night, which results on a continuous change of air temperature and the difference in air temperature between the inside and outside of the courtyard (**Figure 2**). Therefore the

**39**

**Figure 2.**

*Advances in Passive Cooling Design: An Integrated Design Approach*

performance quality of the courtyard house depends on the heat exchange processes between the indoor spaces and the courtyard and then between the courtyard space and the external open spaces. It consists of three main periods; during the first one, the cool night air sinks into the courtyard and flows to the surrounding rooms, and therefore the spaces and surfaces are cooled until noon time. During this period, the courtyard works as storage of cold air and cold air exchange with surrounding rooms. The second period starts at noon, when the sun strikes the floor of the courtyard directly and the temperature of air inside the court's space starts increasing gradually, causing the hot air to move up, and consequently, air is drawn from surrounding rooms to the courtyard space through the openings, resulting in cooling the surrounding rooms. The last period starts when the courtyard and the surrounding rooms get warmer, and all cool air leaks

The passive cooling performance of courtyards depends on three types of elements: the courtyard elements like walls, floor, and landscape greeneries; building elements like windows and built space characteristics; and finally site elements like location, climate, and orientation as summarized in **Table 1**. The cooling performance of courtyards depends on providing the enclosed spaces protection from direct solar radiation and controlled airflow by studying the orientation of the courtyard with regard to the solar path and providing trees for shades and designing with consideration of prevailing winds. **Table 1** summarizes the different variables affecting the cooling performance of a courtyard that designers need to take in consideration in the designing process: Optimizing the passive cooling performance of courtyards in hot regions depends mainly on how to design an efficient storage space by studying shading

out, which prepares the system for a new cycle in the next day.

*3.1.1.1 Courtyard design variables to maximize storing effect*

*The three periods in the working mechanism of a courtyard (author).*

patterns, geometrical shape, and thermal mass material.

*DOI: http://dx.doi.org/10.5772/intechopen.87123*

*Advances in Passive Cooling Design: An Integrated Design Approach DOI: http://dx.doi.org/10.5772/intechopen.87123*

**Figure 2.**

*Zero and Net Zero Energy*

(performance)

buildings' design

**3.1 Storing devices**

*3.1.1 Courtyard*

double glazing window units.

3.*Removal* of gained heat from the interior or exterior sources. This action is required to remove portion of undesirable heat that could not be avoided or slowed. The action can be performed through controlled ventilation, by using wind towers, earth tunnels, and windows to support ventilation requirements.

4.*Slowing* heat transfer from the external climate through the building envelope. This action is conducted by using techniques like efficient insulation and

The four actions of passive cooling, *storing, avoidance*, *slowing*, and *removal*, are discussed in this section in detail with regard to the cooling principles and the designing process, focusing on the variables affecting their performances. Each

• The required actions of implementation from designers in each design process, in stages of early stage (analysis), middle stage (design), and final stage

• Using case studies and examples of integration of devices and actions in the

Some passive systems have direct impact on the architecture design, like the design of an opened atrium or a courtyard, and some have less direct influence, like the type of material and use of louvers or shading systems. Therefore, the level of integration between these systems and the architectural elements varies among the different types of systems and actions. However, it is important to understand the requirements of the chosen passive systems and to make the right decisions of when

Storing refers to keep cold air or low temperature object away from direct heat sources to be used to cool down interior spaces. Throughout architectural history, and particularly in hot climate regions, devices were developed for this purpose as storage design elements, like courtyards, earth spaces, basements combined with wind towers, thermal masses, and sunken courtyards. For the purpose of this research, courtyards

are discussed as one of the most efficient devices in storing cold objects or air.

Courtyard is an opened space surrounded by rooms with openings on the conjoint wall between the rooms and the courtyard space, to allow air exchange daylight, and view. The courtyard as passive design device works as a modifier of the microclimate and acts as a heat sink and cold air storage. Buildings with internal courtyards are characterized as a suitable solution for cooling in hot climate regions

The working mechanism of the courtyard depends on the cycle of day and night, which results on a continuous change of air temperature and the difference in air temperature between the inside and outside of the courtyard (**Figure 2**). Therefore the

device or principal will be discussed based on the following categories:

• The building variables related to the devices and principles

• The required conditions of using the device

and where to integrate them within the designing process.

to provide inner spaces with cold air and daylight.

**38**

performance quality of the courtyard house depends on the heat exchange processes between the indoor spaces and the courtyard and then between the courtyard space and the external open spaces. It consists of three main periods; during the first one, the cool night air sinks into the courtyard and flows to the surrounding rooms, and therefore the spaces and surfaces are cooled until noon time. During this period, the courtyard works as storage of cold air and cold air exchange with surrounding rooms. The second period starts at noon, when the sun strikes the floor of the courtyard directly and the temperature of air inside the court's space starts increasing gradually, causing the hot air to move up, and consequently, air is drawn from surrounding rooms to the courtyard space through the openings, resulting in cooling the surrounding rooms. The last period starts when the courtyard and the surrounding rooms get warmer, and all cool air leaks out, which prepares the system for a new cycle in the next day.

#### *3.1.1.1 Courtyard design variables to maximize storing effect*

The passive cooling performance of courtyards depends on three types of elements: the courtyard elements like walls, floor, and landscape greeneries; building elements like windows and built space characteristics; and finally site elements like location, climate, and orientation as summarized in **Table 1**. The cooling performance of courtyards depends on providing the enclosed spaces protection from direct solar radiation and controlled airflow by studying the orientation of the courtyard with regard to the solar path and providing trees for shades and designing with consideration of prevailing winds. **Table 1** summarizes the different variables affecting the cooling performance of a courtyard that designers need to take in consideration in the designing process:

Optimizing the passive cooling performance of courtyards in hot regions depends mainly on how to design an efficient storage space by studying shading patterns, geometrical shape, and thermal mass material.

*The three periods in the working mechanism of a courtyard (author).*


#### **Table 1.**

*Courtyard design variables (author).*

Zamani et al. [9] studied how to improve the thermal performance of the courtyard by studying various design factors such as proportion, orientation, geometry, opening characteristics, and material. In addition they studied more variables like shading devices, vegetation, and water pools and their impact on heat mitigation.

Sadafi et al. [10] explained how using internal courtyards in terraced houses in tropical regions improves the natural ventilation and thermal comfort. Meir et al. [11] investigated how two semi-enclosed attached courtyards will affect the microclimate in the enclosed courtyards and the attached built volume. Muhaisen [12] showed that courtyards' shading performance depends on the form's properties, location, latitude, and available climatic conditions. Berkovic et al. [13] studied the effect of courtyard design variables, like orientation, horizontal shadings, galleries, and trees, on the thermal comfort of the courtyard's surrounding functions. Muhaisen and Gadi [14] investigated how courtyards' proportions and surface colors considerably influence thermal comfort of the surrounding spaces. Al-dawoud and Clark [15] investigated how different design parameters of the courtyard affect the thermal comfort in spaces surrounding the courtyard. They approved that courtyards are more energy efficient in hot-dry and hot-humid climates in comparison to cold climates.

The design of courtyard with other devices and elements should be made to enhance storing effect and ventilation process, which include the opening, thermal mass, landscape, and building form. Elements that could be integrated should enhance storing action of the courtyard like thermal mass, wall geometry, and landscape. Moreover, to enhance heat exchange between the courtyard and surrounding spaces, other devices could be integrated with the courtyards like wind tower, solar chimney, basement, and opening design and bearing in mind the design requirements in early stages of design process. Therefore, design decisions will have direct impacts on the building's form, orientation, area, zoning, function distribution, and relations with the outdoor and site design.

#### **3.2 Avoidance**

Avoidance, as a passive cooling action, refers to all the methods used to prevent and reduce the amounts of heat gains from direct solar radiation or wind. The key methods of avoidance include different shading devices, building's form, and

**41**

**Table 2.**

Device's variables

*Shading device variables (author).*

*Advances in Passive Cooling Design: An Integrated Design Approach*

landscape. Additional factors, including building's orientations and surfaces' colors

Cho et al. [16] presented an integrated approach for exterior shading device design analysis that included cooling energy performance and economic feasibility in high-rise residential buildings. The research investigated the effect of 48 exterior shading devices on the sunshading/daylighting performance. Palmero-Marrero and OLiveira [17] studied the effect of static louver shading devices on east, west, and south facades for various locations on the energy demands during cooling and heating seasons. The research concluded that the shading device reduced the total annual energy demands in buildings of countries with long dominant cooling seasons and

Datta [18] studied the effect of external fixed horizontal louvers on the thermal performance in the buildings. The study was aimed for reducing the overall energy requirements for the entire year by maximizing the shading device system to reduce solar gains during summer and allow them during winter. The study used TRNSYS as a simulation to maximize the efficiency of the device, and different slat lengths and tilt angles were tested in four Italian cities. Yao [19] evaluated the effect of shading control strategies on the daylighting, visual comfort, and energy performance in

Designing buildings with the passive approach requires integration of many factors together in the process, such as orientation, shading devices, and building form in order to reduce energy consumption in the building as a whole as seen in **Table 2**. Largely glazed facades and large windows have been increasingly used in new buildings, allowing access to daylight, solar heat gains, and external views. The increase in glazed surfaces requires significant attention in building design, regarding the impact they have on cooling, heating, and lighting loads demands. Therefore, it is important to provide these buildings with a proper shading design that would provide interior spaces with thermal comfort by controlling solar heat gains and reducing glare while maintaining the initial purpose of large glazed surfaces to

Many researches were conducted to study the performance of shading devices in order to optimize their performance, save energy, and achieve the maximum thermal comfort. Datta [18] used computer simulation to study variables related to horizontal shading devices and their effect on the thermal performance in buildings in Italy. The study showed that shading devices could help save energy and

Vertical louvers East and west windows block low solar angels

winter

view out

Material To reflect or to absorb sunrays

Diagonal or eggcrate Block low and high angles on east, south, and west directions Overhangs, canopy The depth and height, considering solar noon in summer and

Space to depth Depth-to-spacing ratio to balance between sunrays block and

**Elements Variables How to maximize avoidance actions** Types by Horizontal louvers Southern windows block high solar angles

and textures, can help to prevent gained heat from reaching inner spaces.

*DOI: http://dx.doi.org/10.5772/intechopen.87123*

high ambient temperatures and solar radiation.

provide external views and sufficient daylighting.

*3.2.1 Shading devices*

buildings.

landscape. Additional factors, including building's orientations and surfaces' colors and textures, can help to prevent gained heat from reaching inner spaces.
