for day lighting CHAPTER 3 Window design for day lighting 3.1 Guideline:
for day lighting 3.2 Mandatory clause 3.2.1 For air-conditioned buildings!"!#$$%& # '()!!"!#$$%& * '()! #!"!#$$% Table 3.2.1: Vertical fenestration U-factor and SHGC requirements as recommended in ECBC 2007 Maximum U-factor Maximum SHGC Maximum SHGC for 40% Climate (Wm 2 -K) for WWR 40% < WWR 60% Moderate 6.9 0.4 0.3 3.2.2 For naturally ventilated non-air-conditioned buildings +- Development of Building Regulations and to
for day lighting 3.3 Technical guidelines 3.3.1 Windows in air-conditioned buildings.. + (0.! # + + (0.! 1 (0.!. Figure 3.3.1: Types of heat energy flow occurring through window Development of Building Regulations and to
for day lighting + 2 12 3 &3 & ) -. Figure 3.3.2: Types of double pane glass with low-e coating and gas fills +. - 2 Development of Building Regulations and to
for day lighting Figure 3.3.3: Heat flow through a double-pane glass 2 4 ' 2 2 2 '()! &. '()! '()! ' 2 5 ' 1'()! Development of Building Regulations and to
for day lighting - '()! 1-2 6 2 1 Figure 3.3.4: Projection factor for a window 1 1-1 '()! - '()! 785 1 Development of Building Regulations and to
for day lighting Table 3.3.1: SHGC M factor adjustments for overhangs and fins Overhang 'M' factor for the projection factor Vertical fin 'M' factor for the projection factor 0.25 0.49 Overhang + vertical fin 'M' factor for projection factors 0.75 0.9 9 1.0 + 0.25 0.49 Orient 0.25 0.49 0.5 0.75 0.5 0.75 0.5 Location ation 0.74 0.99 1.0 + 0.74 0.99 1.0 + 0.74 North N 0.88 0.8 0.76 0.73 0.74 0.67 0.58 0.52 0.64 0.51 0.39 0.31 latitude 15 or EW 0.79 0.65 0.56 0.5 0.8 0.72 0.65 0.6 0.6 0.39 0.24 0.16 greater S 0.79 0.64 0.52 0.43 0.79 0.69 0.6 0.56 0.6 0.33 0.1 0.02 Less N 0.83 0.74 0.69 0.66 0.73 0.65 0.57 0.5 0.59 0.44 0.32 0.23 than 15 north EW 0.8 0.67 0.59 0.53 0.8 0.72 0.63 0.58 0.61 0.41 0.26 0.16 latitude S 0.78 0.62 0.55 0.5 0.74 0.65 0.57 0.5 0.53 0.3 0.12 0.04 9 2 " ) 4 44: ; Figure 3.3.5: Wall and window dimensions used for the calculation of the WWR Development of Building Regulations and to
for day lighting - 745 7(5 75 75 44: ;<-=(-4 0 + 06 Figure 3.3.6: Photograph showing wall and window position in a building 9 2. 5 Development of Building Regulations and to
for day lighting - & **% Figure 3.3.7: Day-lit zone explained in the figure as per the description above Development of Building Regulations and to
for day lighting 9 <#-> 4 <?@@ ## 06 Figure 3.3.8: Diagrammatic representation of the light shelf integrated in the window for daylight enhancement ## 06 Development of Building Regulations and to
for day lighting 90 80 70 60 50 VLT 40 30 20 10 0 For Various H:S VLT and WWR H:S - 1:5 H:S - 1:4 H:S - 1:3 H:S - 1:2 H:S - 1:1 Figure 3.3.9: Height to the separation ratio (HS) between buildings 20% 30% 40% WWR 50% 60% Figure 3.3.10: Graph displaying required WWR and VLT for various HS ratio 4 A (=' 44:06 Development of Building Regulations and to
for day lighting 3.3.2 Windows in non-air-conditioned buildings 2 B '()! + 4; Figure 3.3.11: HSA and VSA measurement ' ** - + '2 ** - - Development of Building Regulations and to
for day lighting Figure 3.3.12: Commonly found shading devices ('. 0'. Table 3.3.2 Solar angles for various cardinal directions Solar angles to be cut on various cardinal directions Cardinal directions HSA ( ) VSA ( ) North 37.8 79.4 East - 33.2 West - 58 South -68.9 85.1 North-east (NE) 44 42.3 North-west (NW) -50.9 68.3 South-east (SE) -46 43.3 South-west (SW) 39.1 64 Development of Building Regulations and to
for day lighting..2 ('. - A C * ('.DC 0'.E$ 9 0'. Figure 3.3.13: Horizontal shading devices used for cutting VSA E$ FD 1 D$F %C$ *** 22 9 <' -GH$ 0'.I A0'. Development of Building Regulations and to
for day lighting DC #H$% EC% EC% **D 22 Figure 3.3.14: Vertical shading devices used for cutting HSA 9 <' -G H$ ('.I A('. +2 Figure 3.3.15: Comparison between amounts of daylight penetration for deep overhang and louvers Development of Building Regulations and to
for day lighting + & (=' &44: Figure 3.3.16: Height-to-separation ratio (HS) between buildings Table 3.3.3 Height-to-separation ratio and the required minimum WWR for adequate daylight in commercial buildings (non-air-conditioned) HS ratio (HS between buildings) Minimum WWR (%) required for adequate daylighting 1:5 20 1:4 20 1:3 20 1:2 20 1:1 20 & (=' &44: Development of Building Regulations and to
for day lighting Table 3.3.4 Height-to-separation ratio and the required minimum WWR for adequate daylight in residential buildings (non-air-conditioned) HS ratios (HS between buildings) Minimum WWR (%) required for adequate daylighting 1:5 10 1:4 10 1:3 10 1:2 20 1:1 20 2:1 50 3:1 60 -(='44:! 44: F - ; H (=' <( =' <F=H <#= ' (='# 44: & C$J 4&.. + Development of Building Regulations and to
for day lighting! K L"! #$$C'KD(2A:& "- Table 3.3.5: Desirable wind speed (ms) for thermal comfort conditions: Clause 5.2.3.1 National Building Code 2005 Dry bulb temperature Relative humidity (%) ( C) 30 40 50 60 70 80 90 28 * * * * * * * 29 * * * * * 0.06 0.19 30 * * * 0.06 0.24 0.53 0.85 31 * 0.06 0.24 0.53 1.04 1.47 2.10 32 0.20 0.46 0.94 1.59 2.26 3.04 ** 33 0.77 1.36 2.12 3.00 ** ** ** 34 1.85 2.72 ** ** ** ** ** 35 3.20 ** ** ** ** ** ** Table 3.3.6: Air change schedule SP41: Handbook on Functional Requirement of Buildings Space to be ventilated in residences Bedrooms Living rooms Offices K Required air change per hour 3 6 3 6 3 6 Fig.3.3.17: Image to illustrate window and opening area and option to operate Development of Building Regulations and to
for day lighting 9-9 + 4 2! - 2 L. Development of Building Regulations and to
for day lighting Fig.3.3.18: Image to illustrate wind speed with increasing height of the building ) L" 2 - '2 Development of Building Regulations and to
for day lighting Fig.3.3.19: Diagrammatic representation of stack effect in a room L B DC A#$ *$J *$J - -D$J +2 FCJ Table 3.3.5: Critical height requirement for physiological cooling Activity-based occupancy For sitting on chair For sitting on bed For sitting on floor Recommended height of the bottom side of the opening 0.75 m 0.60 m 0.40 m 2 2 Development of Building Regulations and to
for day lighting 3.4 s! " +!"!.& + #J!"! KDJ K2 # Payback Period Incremental Investment 800 700 Cumulative savings Amount in lakh rupees 600 500 400 300 200 100 0 1 2 3 4 5 6 7 8 9 10 Years Fig.3.4.1: Graphical representation of the payback period showing incremental investment and cumulative savings Development of Building Regulations and to