**2. Shading device design**

Although the computer technology offers infinite numbers of graphics, shading device type and dimension alternatives, and the selection of the optimum solution belong to the designer (Siret, 2004). In other words, performance parameters such as comfort levels, energy saving etc., are those that the decision maker uses to judge the appropriateness of the product (Yezioro,2009). So, the most important part of the shading device design is the selection of the alternatives that provide optimum type and dimension.

This paper describes an approach to simplify and clarify external shading device design. In this regard, Table 1 above, on shading device design criteria has been generated in order to determine how to select the interior comfort shading device dimensions at any site. With the aim of clarifying and facilitating design, "shading device design criteria" have been divided in two main part as seen in Table 1. Some of these criteria vary and some are fixed. In this aspect, the shading mask, which monitors the shading device's performance, and solar radiation, day lighting, climate and comfort graphics, that are used to determine thermal and visual comfort were evaluated as a design criteria to determine the geometry of shading device's optimize dimension and its shape. Then, as seen in the Table 1, by taking into account the criteria interactions with each other, design criteria are selected on the basis of priorities of the climate data of the building's district.

When the design criteria stated in Table 1 are applied to a specific site , parameters related to the dimensions of the window and the shading device could become definite on the direction providing the interior thermal and visual comfort. However, in the building design, dimensions of the windows and shading devices, are used to determine the thermal comfort and sun lighting quality, which sometimes may interact with each other, such as, a shading device that can, on one hand, provide desired shading during the year, and, on the other hand, can reduce day lighting factor (DF) or prevent ventilation (Khaled,2007).

**A. Solar geometry data:** The formulations and ground plane angle of the sun's yearly

**B. Shape and dimension alternatives of window and shading device:** The formulations of

**C. Geographical location and climate data:** Climate data and the required comfort data

As mentioned above, the most important point in the shading device design is to show the dependence of shading device performance on the base of sun's one-year motion. Thereby, calculating the shading device design parameters with traditional methods requires comparison of various drawings and equations on the base of sun's one-year motion. Computerized design with simulation programming, in offering various numerical and graphical alternatives, is help to the designer by shortening the design period. In this article, computerized simulation program of solar tool is used to analyze shading devices in

Although the computer technology offers infinite numbers of graphics, shading device type and dimension alternatives, and the selection of the optimum solution belong to the designer (Siret, 2004). In other words, performance parameters such as comfort levels, energy saving etc., are those that the decision maker uses to judge the appropriateness of the product (Yezioro,2009). So, the most important part of the shading device design is the

This paper describes an approach to simplify and clarify external shading device design. In this regard, Table 1 above, on shading device design criteria has been generated in order to determine how to select the interior comfort shading device dimensions at any site. With the aim of clarifying and facilitating design, "shading device design criteria" have been divided in two main part as seen in Table 1. Some of these criteria vary and some are fixed. In this aspect, the shading mask, which monitors the shading device's performance, and solar radiation, day lighting, climate and comfort graphics, that are used to determine thermal and visual comfort were evaluated as a design criteria to determine the geometry of shading device's optimize dimension and its shape. Then, as seen in the Table 1, by taking into account the criteria interactions with each other, design criteria are selected on the basis of

When the design criteria stated in Table 1 are applied to a specific site , parameters related to the dimensions of the window and the shading device could become definite on the direction providing the interior thermal and visual comfort. However, in the building design, dimensions of the windows and shading devices, are used to determine the thermal comfort and sun lighting quality, which sometimes may interact with each other, such as, a shading device that can, on one hand, provide desired shading during the year, and, on the other hand, can reduce day lighting factor (DF) or prevent ventilation

determining the geometry of window and shading devices.

**D. Function and usage:** The shading device's material, detail and usage.

selection of the alternatives that provide optimum type and dimension.

priorities of the climate data of the building's district.

obtained based on the climate data.

dimension and shape (Marsh, 2003).

**2. Shading device design** 

(Khaled,2007).

motion.


Table 1. Shading device criteria

Furthermore, a shading device dimension, which provides shading in summer months, can provide the same shading in winter months but reduces interior thermal comfort (Szokolay, 1980)). Also, design options of the window and shading devices criteria tools like material, usage, economy and application details may affect the shading devices dimension, too (Miguel, 2008). The colours of the building materials show different behaviour in the aspect of reflecting and absorbing the sun light (Olgyay, 1957). Shading devices, which are made from a material that absorb sun light, used for shading in summer months, may increase heat in the interior space. Besides, window glasses with coatings aimed at reducing incoming solar irradiation, partially reflect or absorb incident solar radiation (Miguel, 2008), so, glazing system effectiveness in controlling solar penetration also affect the shading device in form and material (Alibaba, 2004). In order to resolve the above mentioned problems, shading device dimension and type should be determined first. In this situation, determining optimum device dimensions in a building, that will provide energy efficiency during the year demands series of drawings, which are repeated for every window's dimension, specifying the orientation and geographical position and using the climate data , is essential. Finally, evaluation of all the design criteria stated in Table 1, introduces the design procedure which takes long time and contains complex process. More importantly, it could not always be possible to evaluate all criteria that are in continuous interaction. In this aspect, to give priority to variables or eliminate some of them will be an approach to shading device design. For example, in hot climate zone, interior heat comfort, which can be acquired naturally, could be a priority design criteria for shading device. Furthermore, in cold climate zones, shading device may not be required. Otherwise, protection from sun and heat plays an important role in the Mediterranean zone with a hot climate during the summer, while the problems of areas with cold climate are quite different (Cardinale, 2003). In the residential building district, (which is determined with this procedure)?, selection of one of the effective shading device types and elimination of the others are a solution for making the design easier. Examining the subject critically, only the material, colour, cost and economy that depend on these, can be applied to a shading device with undetermined dimension and shape. From this aspect, in this study, for a selected building area, the necessity of shading device type determination and dimension analyses were made. So, the sun control elements that the users or designers can apply to buildings at Istanbul city, Mediterranean climate zone with latitude 41º North, are seen can not provide the expected energy efficiency because the types and dimensions of external shading devices are not suitable. In this case, priorities of shading device criteria presented in Table 1 are determined on the base of sequence stated below.

#### **2.1 Reasons of the shading device priority that will be applied to the site layout**

Location data and climate in Istanbul city, the area of the research, are given in Figure 1. In general, Mediterranean climate conditions are manifested in Istanbul city (Figure 1). In the Mediterranean climate, prevention of solar heat gain is a preferential criterion in building design (Cardinale, 2003). In Istanbul city, in the planned residential areas which were designed without taking into consideration of solar heat gain, the compulsory mechanical cooling systems to obtain interior comfort in summer results in significant or considerate energy consumption.

As stated in Figure 1, the temperatures in June, July, August and September are at the level that affect interior comfort negatively on the base of ASHREA temperature standards (Table 1.). In addition, solar heat gain that are earned in November, December, January, and February is necessarily for interior comfort. In this case, the 6th, 7th, 8th, and 9th months, bright sunshine duration are priority for shading device criteria for latitude 41ºN. In this respect, shading blocks which shading device has scanned through in one year period, must stay in June, July, August and September months and between 8:00-16:00 o'clock that the time interval solar heat gain is at the highest level. In Figure1 (yellow line), Latitude 41, are seen the time, month, and orientation that are needed for shading.

Fig. 1. İstanbul climate (Green: Comfort zone, Yellow : Solar radiation, Red: Average temperature)

acquired naturally, could be a priority design criteria for shading device. Furthermore, in cold climate zones, shading device may not be required. Otherwise, protection from sun and heat plays an important role in the Mediterranean zone with a hot climate during the summer, while the problems of areas with cold climate are quite different (Cardinale, 2003). In the residential building district, (which is determined with this procedure)?, selection of one of the effective shading device types and elimination of the others are a solution for making the design easier. Examining the subject critically, only the material, colour, cost and economy that depend on these, can be applied to a shading device with undetermined dimension and shape. From this aspect, in this study, for a selected building area, the necessity of shading device type determination and dimension analyses were made. So, the sun control elements that the users or designers can apply to buildings at Istanbul city, Mediterranean climate zone with latitude 41º North, are seen can not provide the expected energy efficiency because the types and dimensions of external shading devices are not suitable. In this case, priorities of shading device criteria presented in Table 1 are

**2.1 Reasons of the shading device priority that will be applied to the site layout** 

Location data and climate in Istanbul city, the area of the research, are given in Figure 1. In general, Mediterranean climate conditions are manifested in Istanbul city (Figure 1). In the Mediterranean climate, prevention of solar heat gain is a preferential criterion in building design (Cardinale, 2003). In Istanbul city, in the planned residential areas which were designed without taking into consideration of solar heat gain, the compulsory mechanical cooling systems to obtain interior comfort in summer results in significant or considerate

As stated in Figure 1, the temperatures in June, July, August and September are at the level that affect interior comfort negatively on the base of ASHREA temperature standards (Table 1.). In addition, solar heat gain that are earned in November, December, January, and February is necessarily for interior comfort. In this case, the 6th, 7th, 8th, and 9th months, bright sunshine duration are priority for shading device criteria for latitude 41ºN. In this respect, shading blocks which shading device has scanned through in one year period, must stay in June, July, August and September months and between 8:00-16:00 o'clock that the time interval solar heat gain is at the highest level. In Figure1 (yellow line), Latitude 41, are

seen the time, month, and orientation that are needed for shading.

Fig. 1. İstanbul climate (Green: Comfort zone, Yellow : Solar radiation, Red: Average

determined on the base of sequence stated below.

energy consumption.

temperature)

## **2.2 Determination of the shading device type that provides shading only at the required time during one year period**

Stereographic diagram in Figure 2 shows shading blocks which includes time, month, and orientation of 180º. In Figure 2, the time, at which the Sun returns from North to South and South to West are considered the base for Istanbul city, which is located at latitude 41oNorth and longitude 28oWest.

The scanned shading blocks in Fig.2 define the required shading block in one year period at latitude 41º.The scanned shading blocks in Figure 2 and Figure 3 can be defined as the "horizontal" type shading device. In this case, horizontal type and south facade (180o ) are a priority-shading device for latitude 41.

Fig. 2. The scanned shading blocks on diagram (Pink plus: Daylight factor, DF, Blue tone: Shading SC%, Black: Altitude of the sun, ALT, yellow: Date, time)
