Adjustment comparison of veranda effect on building shadow area in semi-arid and moderate climates Running title: Veranda effect on building shadow Farah Habib 1, Zahra Barzegar 2, Maryam Cheshmehghasabani 3 1 Associate Professor, Department of Art and Architecture, Science and Research Branch, Islamic Azad University, Tehran, Iran. (f.habib@srbiau.ac.ir) 2 Depatment of Art and Architecture, Payame Noor University (PNU), P.O.Box, 19395-3697, Tehran, Iran. (zahrabarzegar86@yahoo.com) 3 Ph.D. Candidate, Department of Art and Architecture, Science and Research Branch, Islamic Azad University, Tehran, Iran. (m.ghasabani@srbiau.ac.ir) Abstract This research was conducted to assess the performance of horizontal shading device on the building shadow area in two different climates of Iran. The case studies were two holy shrines in Shiraz and (semi arid climate and humid and moderate climate respectively) and were prioritized by Analytical Hierarchy Process weights. The solar angles and shadow area were derived and compared accordingly. The results showed that the shadow on the beneath wall of the lower latitude case study (Shiraz: 29 33 N) was 48.21% in January and 100% in July, and the parallel ratio for was 26.1% in January and 97.22% in July. Through comparison of the monthly shadow area on wall in July with that in January in both climates, the Shiraz and ratios were found to be 2.78 and 4.79, respectively, which indicated that shadow areas in summer were more than those in winter. Therefore, the shadow could cause more outdoor thermal comfort in winter and summer in both climates. Keywords: Energy performance; solar angles; Shading device; Building orientation 1. Introduction Building construction has a major role on the environment because of energy consumption for acquiring building raw materials and generation of waste during construction. Building construction indirectly emits greenhouse gases as waste. Since, environmental issues have become serious and significant; there is need for more energy efficient buildings to cut down its energy needs for operation (Chel & Tiwari, 2009; Dimoundi & Tompa, 2008). The embodied energy and life cycle energy consumption were reported as key parameters for building energy assessment as reported by Casalas. But these parameters are often left out of the regulation and certification proposals as reported by Casala (Chel & Tiwari, 2009; Casals, 2006). Due to industrialization the final energy consumption has risen in the past decade in Iran. The final energy consumption had increased at an annual growth rate of 6.4% from 636.3 Mboe in 1998 to 1187.4 Mboe in 2008 (Iran Institute for International Energy Studies (IIES), 2010). The research results indicated that the residential and commercial sectors were the major energy consumers with 417.5 Mboe in 2008 and they were closely followed by the transportation sector (M. Mohammad Nejad et al., 2011. Energy consumption by residential and commercial sectors had decreased in 2007 and 2008(Iran Ministry of Power, 2010).The fact that building sector currently accounts for nearly 50% of overall gross energy consumption in the world, makes it necessary to focus on energy-saving and efficiency-boosting strategies. Achieving these objectives requires consistent application of four principles: -Improved building envelope (as shade, windows, materials, etc) - Changes in occupants behavior - More efficient energy systems - Use of renewable energies (Pfeiffer et al., 2005, 1162) Along with the importance of indoor thermal comfort, Nicol & Humphreys (2002) stated that the outdoor thermal comfort should be in consideration and be defined as including: - Availability of shade (natural or constructed, vertical or horizontal, fixed or movable Shading devices) - Wind speed - Direction - Solar absorption Shading devices could affect the indoor and outdoor thermal comfort. The role of this passive controller was reported by different researchers and it was mostly applied for simulation. Considering the effect of shading, as an important factor in urban environments, on thermal environments and long-term thermal comfort, Thermal performance and embodied energy analysis of a passive house with a case study of vault roof mud-house in India was conducted. The results showed that based on embodied energy analysis, the energy payback time for the mud-house was determined as 18 years. The embodied energy per unit floor area of building (3702.3 MJ/m2) is quiet high as compared to the mud-house (2298.8 MJ/m2) (Chel & Tiwari, 2009).Hwang et al. (2011) conducted several field experiments to analyze the outdoor thermal conditions in urban streets in central Taiwan. Correlation analysis revealed that thermal comfort was best when a location was shaded during spring, summer, and autumn. During winter, low-shade conditions may contribute to the increase in solar radiation; thus, thermal comfort was improved when a location had little shade in winter (Hwang, et al., 2011). In addition, as shade was one of the main keys in indoor thermal environment, Bessoudo et al. (2010) indicated that shading systems significantly improved operative temperature and radiant temperature asymmetry during cold sunny days, depending on their properties and tilt angle. The shading layers could decrease the amount of heat loss through the façade. They also accessed the indoor environmental conditions with different building envelope and shading properties, facade location and orientation(bessoudo, Tzempelikos, Athienitis, & Zmeureanu, 2010). The results showed that perimeter building zones with high-performance facades (glazing and shading) can maintain comfortable conditions and even eliminate the need for secondary perimeter heating (Bessoudo, et al., 2010). By now, the Analytical Hierarchy Process (AHP) method had been widely applied in the general policy making in buildings (Jaber, Jaber, Sawalha, & Mohsen, 2008 ; Saaty, 2001). In spite of some limitations and critical points (Saaty, 2001), the AHP method was according to many authors a leading MCDA methodology (Pohekar & Ramachandran, 2004) mainly due to its ease of use (Jaber, et al., 2008). 1
The objective of building conservation assessment was to establish and limit the upper boundary for energy consumption in buildings and to promote the utilization of renewable energy and new energy technologies and products. In their paper, Zheng et al. (2010) proposed a methodology based on fuzzy analytic hierarchy process for building energy conservation assessment. Reza, et al. ( 2011) used triple-bottom-line (TBL) sustainability criteria for the selection of a sustainable flooring system in Tehran, Iran. Analytical Hierarchy Process (AHP) was used as a multi-criteria decision making technique that helps to aggregate the impacts of proposed criteria into a sustainability index through a five-level hierarchical structure. Yang et al. ( 2010) presented a method of identifying and weighting indicators for assessing the energy efficiency of residential buildings in China. A list of indicators of energy efficiency assessment in residential buildings in the hot summer and cold winter zone in China was proposed. The group analytic hierarchy process was used to weight the identified indicators. Wong & Li ( 2008) used Analytical Hierarchy Process (AHP) in multi-criteria analysis of the selection of intelligent building systems. By Analytical Hierarchy Process (AHP), important weightings for the criteria were prioritized and assigned. Considering a strong history of vernacular and traditional climatic architecture in Iran (Ghobadian, 2004) as well as the energy crisis in building sector and the effective techniques as well oriented shading devices, the role of shade availability was evaluated in two semi-arid and humid and moderate climates in Shiraz and in the south and north of Iran in 2012 In this study, the better buildings with highly effective shade were determined by Analytical Hierarchy Process (AHP), and to calculate solar position, the shadow areas in the case studies were derived by software and compared. 2. Materials and Methods 2.1. Materials In this study, by choosing two basic climates of Iran including semi-arid and moderate climates, the effect of veranda on the building shadow was evaluated. The first was the semi-arid climate in Shiraz city in the southern part of the central region. The second was the moderate and humid region of in the northeastern part near Sari. The solar hours of Shiraz was about 6.68 folds of and number of the rainy days in was about 2.38 folds of Shiraz in 2009. Therefore, the first climate was more dry and hot than the second one. The elevation, longitude and latitude of Shiraz were 1491m, 052 36'E and 29 33'N, respectively, while those of were -21m, 052 39'E and 36 52'N, respectively, (climate-charts, 2012). Although there were different verandas in front of the famous buildings in both climates, the common type of verandas in front of the shrines Shahechragh in Shiraz and were selected to comply with the objectives of this study. 2.1.1. Shahecheragh in Shiraz The selected building was one of the most famous shrines in the city, which was constructed in Atabakan period in 6 th century and renovated in the past periods for many times (The Iran Geographical and Cartography Longitude Organization, 1995). Shahechragh building was located in the northeast side neighboring another shrine at the southeast side of the shrine s big central court yard. The building was confined to the street from one side and to a veranda from the opposite side. Also, there were rooms and porches in two levels around the court yard. The veranda with the white vertical curtains was prone to remain as an image in the mind of users. The shadow behind it caused the outdoor thermal comfort in hot seasons and also created a family visit near the water and tree in the middle sector (not open and not closed). The veranda was faced to northeast with a 61 orientation from south to east. The length, depth and height of the veranda were 40.2, 5.8 and 12 m, respectively (Fig. 1). The veranda was made of wood; in the afternoon, the white curtain was used on it as a vertical shading device and in the noon the veranda acted as a horizontal shading device. a b a b c Fig. 1: a)the veranda in front of Shahechragh building, A: veranda height = 12 m; B: veranda length= 40.2 m; C veranda weight = 5.8 m, d: the area of the wall back of the veranda= (40.2 * 12) m2 b) The horizontal shading device in front of Shahecheragh (Source: Technical and Engineering Department of Shahecheragh Shrine, 2011; Habib& Barzegar, 2014 ) c) The shadow area beneath a veranda due to the solar angles; right: the case study of Shahcheragh in Shiraz shadow calculation through plan, section and elevation ( Source: Habib& Barzegar, 2014); left: the definition of the shadow calculation (Source: Goswami et al., 2000) 2
2.1.2. The Sqanfar of was constructed in Qajar period in 11th century. The building had an overall veranda in the second floor. The windows around it were open in the summer and the veranda and the building were integrated. This kind of building was a symbolic one used in religious ceremonies in the moderate and humid climate of north of Iran (Rafee, 2011). The material used in the building was mostly domestic wood, some parts of which having changed later in renovations. The elevation of Sqanfar is a simple plain square. The veranda was faced to south west with a 48 orientation from south to west. The length, depth and height of the veranda in the first floor were 6.9, 0.95 and 1.9 m, and in the second floor were 6.9, 0.65 and 1.8 m, respectively (Fig. 2). A C B Fig. 2: Sqanfar image, plan and elevation, A: veranda height = 3.7 m; B: veranda length= 6.9 m; C veranda weight = 0.95 m in the first floor and 0.65 m in the second floor, d: the area of the wall at the back of the veranda= (6.9 3.7) m 2 2.2. Methods To investigate the relations between the building orientation (BO), shading device and the shadow area (A sh ), the following steps were followed: - First, the climates were selected by Köppen climate classification in Iran. The semi-arid and moderate and humid climatic data were analyzed and Shiraz and were extracted. - The effective parameters of choosing buildings as case studies were derived and the suggested buildings were evaluated. Some of these parameters were building orientation (BO), existence of fixed horizontal shading device, quality of horizontal shading device, height, length and depth of shading device, land use similarity, etc. In the case study selection step, building orientation (BO) was one of the most important factors. The prioritization process was carried out by Analytical Hierarchy Process (AHP). The buildings with suitable horizontal shading device were compared and gained a specific weight. Using the weights, the best ones were chosen to be the religious buildings including Shahechragh and Sqanfar shrines. - Then the data of buildings as building orientation (BO) plan, elevation and sections were collected. - To calculate solar angles in this step, summer and winter were chosen because of the changing outdoor climatic conditions in both of the case studies, and 1th, 10th and 20th of January and July were chosen for studying. - On the intended days, from sunrise to sun set the solar angles of both cities were hourly calculated by Duffie method (Duffie & Beckman, 1991) by Matlab software. - Considering the solar angles, Auto CAD software was used to calculate shadow area through the plan and sections of the case studies as explained in the related section. - Next, shadow area (A sh ) from both case studies was compared and the charts were drowned and analyzed. - For indoor thermal comfort research, outdoor and indoor temperatures especially during hot season (July) were obtained and compared in Shahecheragh. - Finally, in veranda, courtyard and indoor comfort conditions in 15th July were calculated. Köppen climate classification system, including the criteria for various subdivisions (Ahrens, 2007), was the most famous climate classification(oliver, 2005) used in this paper for classification of different parts of Iran (Soflae, 2005). Due to its widespread application and ease of use, AHP developed by Saaty (Saaty, 1980) has been extensively studied during the last 20 years. It has been widely used to address multi-criterion decision making problems. The AHP approach was a popular 3
multi-attribute approach aimed at arriving at a rank order of alternatives characterized by single synthesizing values representing the decision maker s preference (Chinese, Nardin, & Saro, 2011). The AHP consists of three main operations, including hierarchy construction, priority analysis, and consistency verification (Ho, 2008). The hierarchy of the decision variables was the subject of a pair wise comparison of the AHP. The pair wise comparison was established using a nine-point scale which converts the human preferences to available alternatives as equally, moderately, strongly, very strongly or extremely preferred (Ho, 2008). Duffie used to calculate the solar angles and radiation in different climates based on latitude and hour angle (Duffie & Beckman, 1991). Due to the need for solar angle at the first calculation, Duffie method was used in this study ( Calculation of solar angles section). Afterwards, the shadow area (A sh ) was calculated by Auto CAD and Matlab software ( Calculation of A sh ). Accordingly, the results were evaluated in a comparative system by SPSS and Excel software. 3. Results and Discussion 3.1. Calculation of solar angles Due to the direct relationship between sun positions and the quality and quantity of shading device design, sun position components, including altitude (α s ) and azimuth (γ s ) were calculated in this step as follows: sinα s = sinϕ sinδ + cosϕ cosω cosδ (1) δ = declination, α s = solar azimuth angle ϕ = regional latitude ω = the hour angle α s was calculated using Duffie method(duffie & Beckman, 1991), while δ and ω were calculated based on different formulas(cooper, 1969). α s was calculated for period of sunrise to sun set in each hour, and α s during 1st, 10th and 20 th of January and July was obtained by Matlab. In addition, γ s was calculated through(quaschning, 2005): sinω cosδ sinγ s = (2) cosα s Moreover, γ s during 1 st, 10 th and 20 th of January and July was also obtained. 3.2. Calculation of shadow area (A sh ) The shading device caused an hourly shadow on the building envelope and the shadow was calculated by means of α s and γ s angles. For this purpose, Auto CAD Graphical method was applied. In this method, the shadow height was calculated by drawing α s versus the shading device edge in section. shadow area (A sh ) was also illustrated and finally it was calculated by drawing γ s versus the shading device edge in plan. Therefore, the hourly shadow area (A sh ) was calculated for each hour due to the continuous change (Tables 1 and 2). Table 1: Shadow area (A sh ) on the wall In January (m 2 ) Hours Shahechragh in Shiraz Sunrise Morning Noon Afternoon Sunset 8 9 10 11 12 13 14 15 15:25 16 Day Shadow area (A sh ) (m 2 ) 1st 0 0.73 2.22 2.58 4.00 4.51 4.20 3.39 2.30 0 0.79 0 10th 0 0.73 2.22 2.46 4.08 4.69 4.44 3.63 2.30 0 0.91 0 20th 0 0.73 2.37 2.37 4.35 5.08 4.77 3.97 2.83 0 1.18 0 1st 0 61.7 119.7 173.3 211.8 207.5 142.2 186.6 133.7-77.5 0 10th 0 62.8 115.6 176.3 215.8 216.7 154.2 193.7 137.5-76.1 0 20th 0 65.6 126.66 185.55 229.46 232.57 142.2 208.3 150.5-89.7 0 Table 2: Shadow area (A sh ) on the wall in July (m 2 ) Hour Shahechragh in Shiraz Sunrise Morning Noon Afternoon Sunset 6 7 8 9 10 11 12 13 14 15 16 17 18 Day Shadow area (A sh ) (m 2 ) 1st 0 1.62 2.40 5.57 8.61 14.06 18.92 18.92 18.92 13.88 8.89 5.82 3.59 1.69 0 10th 0 1.18 2.31 5.48 8.43 12.91 18.92 18.92 18.92 13.71 8.83 5.19 3.54 1.68 0 20th 0 1.01 3.15 5.20 8.14 12.41 18.92 18.44 18.44 13.44 8.8 5.74 3.46 1.62 0 1st 0 49.7 120.4 210.2 210.2 335.9 476.5 419.3 482.4 482.4 371.8 237 140.8 65.6 0 10th 0 47.5 117.3 203.9 317.9 478.1 482.4 420.5 482.4 482.4 372 237 140.8 61.4 0 20th 0 43.1 111.8 200.4 323.27 479.5 482.4 419.3 482.4 482.4 362.9 232.6 137.5 62.8 0 4
In calculating daily Shadow area (A sh ), the area beneath the shadow daily chart was calculated. Shadow area (A sh ) was considered for the 1 st day to the 9 th day similar to the 1 st day, for the 10th day to the 19 th day similar to the 10 th day and for the 20th day to the last day of the month similar to the 20 th day. The total area showed the shadow on the wall during the month (Table 3). Table 3: Daily and monthly Ash on the wall (m2) Month January July Day 1 st 10 th 20 th 1 st 10 th 20 th Shadow area 24.72 25.46 27.65 122.89 120.02 118.61 Daily on the wall (m2) 247. 2 254. 6 276.5 1228.9 1200.2 1304.71 Decade Monthly 778.8 3733.8 Shadow area on the wall (m2) Shahechragh in Shiraz Daily 79632.9 81578.6 86526.3 232150.9 230319.8 228980.6 Decade 716696.1 815786 1038315.8 2089358.8 2303198.4 2747767 Monthly 2570797.9 7140324.2 The shadow area on the wall was depended on the seasonal and daily time. For better comparison between the case studies with different wall areas, the shadow areas converted to the percentage of the wall which had shadow. Finally, the percentages were compared with each other (Table 4). Table 4: Case studies shadow area (A sh) percentage on the wall in 10 th of January and July January Sunrise Morning Noon Afternoon Sunset Hour 8 9 10 11 12 13 14 15 15:25 16 0 3.75 12.18 12.18 22.35 26.10 24.51 20.40 14.54 0 6.06 0 Shahechragh in Shiraz 0 13.6 26.26 38.46 47.57 48.21 29.48 43.18 31.2 0 18.6 0 July Sunrise Morning Noon Afternoon Sunset Hour 6 7 8 9 10 11 12 13 14 15 16 17 18 0 5.2 16.2 26.7 41.8 63.8 97.22 94.75 94.75 69.06 45.22 29.49 17.78 8.32 0 Shahechragh in Shiraz 0 8.9 23.2 41.5 67.0 99.4 100 86.92 100 100 75.22 48.21 28.50 13.01 0 3.3. Solar angles Investigation of the solar angles elucidated some important points. The eastern and western surfaces of the buildings caught the inclined radiation of sunrise and sunset, and the southern envelope received the vertical radiation (Fig. 3). Thus, the southern part needed horizontal shading device and both of the eastern and western surfaces needed vertical ones. On the other hand, in winter, low altitude-solar radiation had the most profound effect on the southern side of the building; whereas, in summer, this phenomenon was to the contrary. Therefore, solar radiation could be more appropriately utilized in winter and the unfavorable hot summer radiation could be more effectively monitored by a well-orientation design and application of a horizontal shading device in the building southern side (Fig. 3). Comparison of the sun altitude angle in July in the case studies showed that the main difference was in the noon as in Shiraz the altitude was higher and therefore the sun shined more vertical. However, in January the daily chart of both case studies differed and again the more vertical radiation belonged to Shiraz. Unlike the altitude angle, the azimuth angle comparison indicated that the main difference in the both case studies azimuth angles was in July with the marked differences in forenoon and afternoon. Thus, the forenoon and afternoon radiation direction in Shiraz was more inclined, but the noon radiations directions were the same (Fig. 3). 5
Fig. 3: Comparison of azimuth and altitude angle in and Shiraz, left: 10 th July; right: 10 th January According to the results, regional sun chart was delineated for the studied interval time (Fig. 4). The 10th of January and July of sun charts for the both case studies showed that the difference between vertical and horizontal radiation direction in summer and winter in the southern part could contribute to absorb winter radiation as heating and to avoid summer radiation as cooling by the designed horizontal shading device. In addition, the case study in higher latitude had more vertical radiation. Fig. 4: Sun chart comparison of the 10 th of January and July 3.4. Shading device After defining and calculating the shading device effect, the following results were achieved: - In January, hourly shadow area increased in Sqanfar from sunrise to 9 AM. and afterward, while due to the sun rotation from right side of the building to the left (west), it decreased. However, in Shahecheragh this rotation occurred in 1PM. (because of the difference between Building Orientation of the case studies). Furthermore, in Sqanfar and Shahecheragh, shadow area (A sh ) of 20th January raised to maximum till 12 AM. as the sun shined vertically and the shading device became more effective. By decreasing afternoon altitude, shadow area (A sh ) reduced. At 15:15, in Sqanfar, sun radiated vertically to façade; therefore, shadow area became 0. However, in Shahechragh, the chart showed a downward trend up to sunset (Fig. 5). - In July, the charts reported some contrast between the hourly shadow trend in each day of this month and January. From 11AM. to 1PM. the maximum shadow area (A sh ) already covered the entire envelope in shadow and then it reduced from 1PM. to sunset. In 1PM, the shadow area decreased to some extent but the noon shadow was perfect (Fig. 5). - The diagrams for January and July in both case studies were almost the same, with the July graph slope being more sloped. Therefore, more shadow was casted on the envelopes in July. In summer, when the sun shined more disturbingly, hourly shadow covered the major part of the wall and cooled the space. In January, in contrast, decrease of shadow area (A sh ) demonstrated the solar achievement which made the space warmer (Fig. 5). 6
- Comparing the three studied days in January (1 st, 10 th, 20 th ), it was revealed that from beginning to the end of the month, shadow area (A sh ) increased, whereas in July it was to the contrary. Naturally, the difference between July days was minor and negligible. - As shadow of the shading device on the building was stretched entirely from 11 to 13 o'clock in July, a cool area was obtained. However in January, the maximum shadow area (A sh ) from 11 to13 o'clock in Sqanfar was less than a quarter of wall, and in Shahechragh it was about half the wall, which allowed the habitants to enjoy the eastern and western favorable solar radiation in Sqanfar and Shahecheragh, respectively. One of the disadvantages of the Sqanfar building orientation (BO) was rotation toward west which was due to penetration of western solar radiation to the building. By facade vertical grids, this problem was solved to some extent. And as an appropriate technique, the Shahechragh building orientation (BO) was toward south east and only the horizontal shading device was sufficient for outdoor shading. Through comparison of the monthly shadow area (A sh ) in July with that in January in both climates, the Shahechragh and Sqanfar ratios (A sh July / A sh January) were found to be 4.79 and 2.78, respectively. Therefore, the horizontal shading device was effective in both climates, because of the controlling hot radiation in summer of semi-arid climate and the solar absorption in winter of moderate climate. However the winter shadow in semi arid caused perfect outdoor thermal comfort and also summer one in moderate climate. The shadow area (A sh ) percentage of Shiraz in noon of 20th January was 48.21% and that of was 26.10%. The shadow area dependent on the horizontal shading device in was more effective in January because of the more vertical radiation absorption in noon. Moreover, the shadow area (A sh ) percentage of Shiraz in noon (14 o clock) of 20th July was 100% and that of was 69.06%. As a result, the shadow area dependent on the horizontal shading device in Shiraz was more effective because of the less vertical radiation absorption in July. (Table 4 and Fig. 5 and Fig. 6) Fig. 5: Comparison of daily shadow area (A sh) percentage of the case studies in 20th July and 20th January Table 5: Building Orientation results about shading device need in days of July and January hourly. Mounth Device type No shading device Horizontal shading device Vertical shading device Shahechragh in Shiraz January Before 9 9 to15:30 after 15:30 July Before 10 10to14:30 after 14:30 Annual Before 9 9 to 14:30 after 14:30 January Before 10:30 10 to15:30 after 15:30 July Before 10 10:30 to 17 after 17 Annual Before 10 10 to 15:30 after 15:30 In addition, through analyzing BO in the case studies, it was indicated that with two horizontal and vertical shading devices, the solar radiation could be controlled in the times given in Table 5. By merging winter and summer conditions, the shading device need was divided into 3 different zone time, firstly no morning eastern shading device need; then noon southern horizontal shading device need; finally afternoon western vertical shading device need (Table 5). 7
61 N 48 N Comparing Altitude angle and Shadow Area in Summer and Winter in case study of Shahcheragh in Shiraz No. 1 2 3 Shahcheragh Building Orientation (61 to South East) Specifications of Shahcheragh Veranda dimention Area of veranda floor Depth 58m Length 40.2m Veranda Height 12m Area of wall 40.2* 12 (a) (b) Fig. 6: (a) Sketches Comparison of Shadow Area in summer and winter in case study of Shahcheragh in Shiraz; (b) Sketches Comparison of Shadow Area in summer and winter in case study of. 3.5. Air temperature and comfort condition Comparing Altitude angle and Shadow Area in Summer and Winter in case study of Saqanfar h Building Orientation (48 to West) Specifications of Saqanfar Veranda No. dimention 1 Area of veranda Depth 0.65 m First floor Length 6.30 m 2 floor Veranda Height 1.80m 3 Area of wall 1.80* 6.30 m 4 Area of veranda Depth 0.95m Second floor Length 6.90m 5 Floor Veranda Height 1.90 m 6 Area of wall 1.90 * 6.90 m Due to such consideration, outdoor temperature and indoor temperature especially during hot season were significantly different. Fig. 7 shows such difference in July-2012 as a hottest month of the year, in Shahecheragh. The data of savad-kouh were not available. Obviously, some parameters, like thermal mass, have effects on indoor temperature. Fig. 8 also, shows comfort condition on 15 th July in veranda, courtyard and indoor condition. Fig. 7: comparison between outdoor and indoor condition in Shahecheragh Fig. 8: Comparison between indoor, courtyard and veranda comfort condition 8
4. Conclusion The objective of this study was to investigate the effect of building orientation (BO) and shading device on the shadow area on the wall. Shahechragh in Shiraz and with latitudes of 29 33'N and 36 52'N, respectively, were chosen to be evaluated as case studies. Investigation of solar angle and shadow area (A sh ) values as well as comparisons showed the important role of building orientation (BO) and shading device. Therefore, considering the traditional and vernacular architecture of the studied regions, the buildings were found to be capable of preparing better thermal comfort using the mentioned techniques by causing climatic shadow on the envelopes. Firstly, by calculating the solar angles, some guidelines for designing and constructing buildings in the temperate and semi-arid climates were considered as the eastern and southern surfaces were more desirable in winter and the southern one were more desirable in summer. Therefore, the southern surface was the best for solar utilization in these two seasons. Adjustment comparison of sun position in the case studies revealed that the southern and western façade required horizontal and vertical shading device, respectively. The solar altitude angle in Shiraz was greater due to the latitude difference. The maximum altitude of Shiraz was 83.5 in July and 40.3 in January, while the maximum altitude of was 76.3 in July and 34 in January. However, the azimuth angles in summer and winter were more similar. In spite of the perfect shading device, one of the disadvantages of the Sqanfar building orientation (BO) was rotation toward west which was due to penetration of western solar radiation to the building. By facade vertical grids, this problem was partially solved, but the vertical shading-needed zone appeared since 2:30 PM. in July. As an appropriate technique, the Shahechragh building orientation (BO) was toward south east and the horizontal shading device was supplied for the most outdoor shading and the vertical shading was needed only after 5 PM. in July. At last, evaluation of horizontal shading device shadow area (A sh ) showed that when the sun shined more disturbingly in summer in both case studies, hourly shadow covered the major part of the wall creating a cool space. In January, in contrast, decrease of shadow area (A sh ) demonstrated the solar achievement which made the space warmer. Shadows of shading devices were stretched entirely on the buildings from 11 to 13 o clock in July resulting in a cool area. However, in January, the maximum shadow area (A sh ) from 11 to13 o clock in Sqanfar was less than a quarter of the wall and in Shahechragh it was about half the wall. Comparing the monthly shadow area (A sh ) in July and January in both climates, the ratios of Shahechragh and Sqanfar were obtained to be 4.79 and 2.78, respectively. Therefore, the horizontal shading device was effective in both climates as it controlled the hot radiation in summer in semi-arid climate and the solar absorption in winter in moderate climate. However, the winter shadow in semi-arid climate and the summer shadow in moderate climate caused a perfect outdoor thermal comfort. Thus, according to the obtained vernacular building results, this hypothesis is approved that minimum solar radiation in summer (by maximum shadow for cooling) and maximum solar radiation in winter (by minimum shadow for heating) can be gained owing to the horizontal shading device and desirable orientation with its required shadow. The mentioned results, if considered in current buildings and urban planning projects, could reduce the cooling and heating need be. The shadow area (A sh ) percentage of Shiraz in noon of 20th January was 48.21% and that of was 26.10%. Therefore, the shadow area depending on the horizontal shading device in was more effective in January because of the higher vertical radiation absorption in noon. Moreover, the shadow area (A sh ) percentage of Shiraz in noon (2PM.) of 20th July was 100 % and that of was 69.06%. The shadow area depending on the horizontal shading device in Shiraz was more effective because of the lower noon vertical radiation absorption in July. As a result,about indoor and outdoor thermal comfort comparison, outdoor temperature had significant difference from indoor temperature especially during hot season in Shahecheragh. Veranda, courtyard and indoor comfort condition on 15th July shows the controlling role of veranda in maintaining more thermal comfort than court yard. According to the results, it could be stated that the best orientation for Shiraz and is rotation toward southeast. In addition, the type of the shading devices and the required difference time in both climates were identified. Acknowledgements We would like to thank Support from Tehran Science and Research Branch, Islamic Azad University, Tehran, Iran, research project entitled Evaluating the effect of building orientation on vertical shading device performance (Case study: religious building in four different climate in Iran) is greatly appreciated. Nomenclature ãs Solar azimuth angle 0 o to + 360 o ; clockwise from North origin ás Solar altitude angle 0 o to + 90 o ; horizontal is zero δ Declination 0 o to ± 23.45 o ; Northern hemisphere is +ive (Suffix -ive:an adjective suffix signifying relating or belonging to, of the nature of, tending to; as affirmative, active, conclusive, corrective, diminutive.) ϕ Latitude 0 at the Equator to 90 ω Hour angle 0 o to ± 180 o ; solar noon is zero, afternoon is +ive, morning is ive Abbreviations BO Building Orientation 0 o to + 360 o ; clockwise from North origin A sh Shadow Area Squaremeter (m 2 ) 9
REFERENCES Ahrens, C. D. (2007). Meteorology Today: An Introduction to Weather, Climate, and the Environment. Belmont: Thomson Higher Education. Bessoudo, M., Tzempelikos, A., Athienitis, A. K., & Zmeureanu, R. (2010). Indoor thermal environmental conditions near glazed facades with shading devices Part I: Experiments and building thermal model. Building and Environment, 45(11), 2506 2516. doi: http://dx.doi.org/10.1016/j.buildenv.2010.05.013 Casals,XG. (2006). Analysis of building energy regulation and certification in Europe: their role, limitations and differences. Energy Build 2006;38:381 92. Chel, A., & Tiwari, G. N. (2009). Thermal performance and embodied energy analysis of a passive house case study of vault roof mud-house in India.Applied Energy, 86(10), 1956-1969, doi: http://dx.doi.org/10.1016/j.apenergy.2008.12.033. Chinese, D., Nardin, G., & Saro, O. (2011). Multi-criteria analysis for the selection of space heating systems in an industrial building. Energy, 36(1). doi: http://dx.doi.org/10.1016/j.energy.2010.10.005 Cooper, P. I. (1969). The absorption of radiation in solar stills. Solar Energy, 12(3). doi: http://dx.doi.org/10.1016/0038-092x(69)90047-4 Dimoudi, A., Tompa, C. (2008). Energy and environmental indicators related to construction of office buildings. Resour Conserv Recycl;53:86 95. Duffie, J. A., & Beckman, W. A. (1991). Solar Engineering of Thermal Processes (Second ed.). New York: John Wiley & Sons Inc. Ghobadian, V. (2004). Climate investigation of the Iran traditional buildings (Third ed.). tehran: Tehran University press. Ho, W. (2008). Integrated analytic hierarchy process and its applications A literature review. European Journal of Operational Research, 186(1), 211 228. doi: http://dx.doi.org/10.1016/j.ejor.2007.01.004 Goswami, D.Y., Kreith,F., Kreider, J.F. (2000).Principles of solar engineering. 2 ed, Philadelphia, Taylor & Francis. Habib, F., Barzegar, Z. (2014). Evaluation of the horizontal shading device effect on building envelopes received solar radiation a case with SE orientation in Shiraz. Advances in Environmrntal Biology, 8(4). Hwang, R.-L., Lin, T.-P., & Matzarakis, A. (2011). Seasonal effects of urban street shading on long-term outdoor thermal comfort. Building and Environment, 46(4). doi: http://dx.doi.org/10.1016/j.buildenv.2010.10.017 Iran Institute for International Energy Studies (IIES). (2010). Hydrocarbon balance 2008. Tehran.Iran Ministry of Power. (2010). Energy balance 2008. Tehran. Jaber, J. O., Jaber, Q. M., Sawalha, S. A., & Mohsen, M. S. (2008). Evaluation of conventional and renewable energy sources for space heating in the household sector. Renewable and Sustainable Energy Reviews, 12(1), 278 289. doi: http://dx.doi.org/10.1016/j.rser.2006.05.004 Nicol, J. F., & Humphreys, M. A. (2002). Adaptive thermal comfort and sustainable thermal standards for buildings. Energy and Buildings, 34(6), 563 572. doi: http://dx.doi.org/10.1016/s0378-7788(02)00006-3 Oliver, J. E. (2005). Encyclopedia of World Climatology (Encyclopedia of Earth Sciences Series) (Fifth ed.). Dordrecht. Pfeiffer, A., Koschenz, M., & Wokaun, A. (2005). Energy and building technology for the 2000 W society Potential of residential buildings in Switzerland. Energy and Buildings, 37(11), 1158 1174. doi: http://dx.doi.org/10.1016/j.enbuild.2005.06.018 Pohekar, S. D., & Ramachandran, M. (2004). Application of multi-criteria decision making to sustainable energy planning e a review. Renewable and Sustainable Energy Reviews 8(4), 365-381. doi: http://dx.doi.org/10.1016/j.rser.2003.12.007 Quaschning, V. (2005). Understanding Renewable Energy Systems. London: Earthscan. Rafee, Z. (2011). Nafar development process in vernacular architecture of Mazandaran, baghe nazar Bagh Nazar, 19. Reza, B., Sadiq, R., & Hewage, K. (2011). Sustainability assessment of flooring systems in the city of Tehran: An AHPbased life cycle analysis. Construction and Building Materials, 25(4), 2053 2066. doi: http://dx.doi.org/10.1016/j.conbuildmat.2010.11.041 Saaty, T. L. (1980). the Analytic Hierarchy Process. New York: McGraw-Hill. Saaty, T. L. (2001). Fundamentals of decision making and priority theory with the Analytic Hierarchy Process. Pittsburgh: RWS Publications. Soflae, F. (2005). division lines between climates, the environmental effect of central courtyard on the sustainable residential buildings in arid climate of Iran. Ph.D., Science and research Branch, Islamic Azad University, Tehran. Technical and Engineering Department of Shahecheragh Shrine. (2011). the Shrine Plan and Elevations. In. Shiraz The Iran Geographical and Cartography Longitude Organization. (1995). Iran face; Tourism and travel guide. Tehran. Wong, J., & Li, H. (2008). Application of the analytic hierarchy process (AHP) in multi-criteria analysis of the selection of intelligent building systems. Building and Environment, 43(1), 108-125. doi: http://dx.doi.org/10.1016/j.buildenv.2006.11.019 Yang, Y., Li, B., &, Yao R. (2010). A method of identifying and weighting indicators of energy efficiency assessment in Chinese residential buildings. Energy Policy, 38(2), 7687 7697. doi: http://dx.doi.org/10.1016/j.enpol.2010.08.018 Zheng, G., Jing, Y., Huang, H., Shi, G., & Zhang, X. (2010). Developing a fuzzy analytic hierarchical process model for building energy conservation assessment. Renewable Energy, 35(1), 78 87. doi: http://dx.doi.org/10.1016/j.renene.2009.07.008 10