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100 METU JFA 2012/1 Figure 4. The analyse grid. Figure 5. Summer Period percentage shaded (%) .Figure 6. Winter Period percentage shaded (%). Figure 7. annual percentage shaded (%). ESRA SAKINÇ and Müjgan ŞEREFHanOĞLU SÖZEn as seen in <strong>the</strong> diagrams, <strong>the</strong> nor<strong>the</strong>rn and nor<strong>the</strong>ast areas <strong>of</strong> <strong>the</strong> study zone have <strong>effect</strong>ive shading, nearly entire study zone has shading during winter and a limited area between west and east has shading during summer. Overshadowing Quantity Shadow diagrams in Figure 7 display <strong>the</strong> dimensions <strong>of</strong> shadows and limits <strong>of</strong> <strong>the</strong> affected area. Never<strong>the</strong>less, to evaluate <strong>the</strong> <strong>effect</strong>s <strong>of</strong> shadows in a holistic way, we should also know ‘how much solar energy is blocked in total during a year’. Overshadowing quantity, total amount <strong>of</strong> shading on a surface during a period, gives a cumulative value for <strong>the</strong> reduction at <strong>the</strong> solar access <strong>of</strong> a surface. In this step, whole study zone has been analyzed in means <strong>of</strong> shading percentages (%) in order to determine <strong>the</strong> most affected areas from shading. For calculations, analysis grid <strong>of</strong> 10m x 10m sizes, which has <strong>the</strong> same physical properties with <strong>the</strong> study zone has been used (Figure 4). The Shading Percentages within <strong>the</strong> Study Area The percentages and <strong>the</strong> limits <strong>of</strong> shaded area for: a) Summer period (1 April – 1 October between 6:00 – 18:00) ( Figure 5) b) Winter period (1 October – 1 April between 7:00 – 17:00) ( Figure 6) c) Annual (1 January – 1 December between 7:00 -- 17:00) ( Figure 7) are as <strong>the</strong>y are seen in Figure 5-7. According to <strong>the</strong>se calculations, • overshadowing affects an area <strong>of</strong> approximately 260m wide, • nor<strong>the</strong>ast side <strong>of</strong> <strong>tall</strong> <strong>buildings</strong> is <strong>the</strong> most affected area, and • <strong>the</strong> average shading percentages are; 8.61% in summer, 13.35% in winter, and 9.92% per annum. However, as it is clearly seen in <strong>the</strong>se graphics, shading percentages in <strong>the</strong> study area are ranging from 5% to 40% which means overshadows affects some <strong>buildings</strong> more than o<strong>the</strong>rs. In order to understand how <strong>the</strong> overshadowing <strong>of</strong> <strong>tall</strong> <strong>buildings</strong> is affecting <strong>the</strong> area, <strong>the</strong> study zone has been analyzed in means <strong>of</strong> blocks, (a,B,C,D....n) as seen in Figure 8. The number <strong>of</strong> houses that have same shading percentages and <strong>the</strong> total number <strong>of</strong> house units that are affected from shading in each block in different periods, are given in Table 2. Based on <strong>the</strong> information obtained from Table 2, exposure rate <strong>of</strong> blocks (in means <strong>of</strong> <strong>buildings</strong>) from shadows is given in Table 3. As it is seen, nearly all study area is affected from shading during winter and blocks A, B, C that are <strong>the</strong> most affected areas. As it is seen in Figure 5-7, and in Table 1, houses in <strong>the</strong> study zone have different shading quantity. In order to understand <strong>the</strong> <strong>effect</strong>iveness <strong>of</strong> shading percentages in <strong>the</strong> study zone, table 4 is produced which gives <strong>the</strong> number <strong>of</strong> houses that have <strong>the</strong> same shading rate, <strong>the</strong> <strong>effect</strong>iveness <strong>of</strong> shading rates and shading percentage <strong>of</strong> <strong>the</strong> study zone in total. During winter season, nearly all (84%) <strong>of</strong> <strong>the</strong> zone is affected from overshadowing while 45% <strong>of</strong> <strong>the</strong> zone is affected during summer and <strong>tall</strong> <strong>buildings</strong> are overshadowing half <strong>of</strong> <strong>the</strong> zone (58 %) throughout <strong>the</strong> year. While very limited number <strong>of</strong> houses have 40, 35, 30 % shading, <strong>the</strong> 10% and 5% are most <strong>effect</strong>ive shading percentages.
THE EFFECT OF TALL BUILDINGS ON SOLAR ACCESS METU JFA 2012/1 101 Figure 8. Blocking properties <strong>of</strong> <strong>buildings</strong> in <strong>the</strong> study area. Blocks SUMMER WINTER ANNUAL Shading % Shading % Shading% total total The number <strong>of</strong> houses in <strong>the</strong> blocks. A: 14 B: 33 C: 33 D: 30 E: 30 F: 25 G: 9 H: 24 I: 8 J: 7 K: 4 (4-6 flats) L: 18 (4-6 flats) M: 28 N: 29 TOTAL 292 25 20 15 10 5 40 35 30 25 20 15 10 5 30 25 20 15 10 5 A 5 1 2 3 3 14 3 2 2 1 2 4 - - 14 4 3 3 2 2 - 14 B - 4 1 2 13 20 - - 3 10 13 7 - - 33 - - 2 16 11 4 33 C - - - 6 25 31 - - - - 9 9 15 - 33 - - - - 10 23 33 D - - - - - 0 - - - - - - 11 8 19 - - - - - 12 12 E - - - - 6 6 - - - - - 4 11 15 30 - - - - - 16 16 F - - - - 5 5 - - - - - 3 5 17 25 - - - - - 14 14 G - - - - 5 5 - - - - - - - 9 9 - - - - - 9 9 H - - - 7 12 19 - - - - - - 3 7 10 - - - - - 10 10 I - - - 1 2 3 - - - - - 4 4 8 - - - - 2 4 6 J - - - - 1 1 - - - - 2 2 3 - 7 - - - - 3 3 6 K - - - - - 0 - - - - 1 1 - 2 4 - - - - 1 1 2 L - - 2 3 1 6 - - - 2 1 3 6 6 18 - - - 2 3 8 13 M - - - - 19 19 - - - - - - - 4 4 - - - - - - - N - - - - - 0 - - - - - - - 29 29 - - - - - - - Table 2. The number <strong>of</strong> houses that have same shading percentages in each block. Table 3. Shading rates <strong>of</strong> blocks in means <strong>of</strong> building unit. Table 4. The <strong>effect</strong>iveness <strong>of</strong> shading percentages by means <strong>of</strong> house unit (%). Period Affecting percentage from overshadowing (%) A B C D E F G H I J K L M N Summer 100 61 94 0 20 20 56 79 38 14 0 33 68 0 Winter 100 100 100 63 100 100 100 42 100 100 100 100 14 100 Annual 100 100 100 40 53 56 100 42 75 86 50 72 0 0 The <strong>effect</strong>iveness <strong>of</strong> shading percentages (number <strong>of</strong> houses and %) 40 35 30 25 20 15 10 5 Total Summer - - - 5 (%2) 5 (%2) 5 (%2) 22 (%8) 92 (%32) 129 (%45) Winter 3 (%1) 2 (%1) 5 (%2) 14 (%4) 28 (%10) 37 (%13) 60 (%20) 101 (%34) 250 (%84) Annual - - 4 (%1) 3 (%1) 5 (%2) 20 (%7) 33 (%11) 104 (%36) 169 (%58) total
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