U-VALUE
(THERMAL
TRANSMITTANCE)
Heat transmission in unit time through unit area of a material
or construction and the boundary air films, induced by unit
temperature difference between the environments on each side.
Units of U-value are W/m2/ok
VISIBLE LIGHT
TRANSMITTANCE
(VLT)
Amount of light transmitted through glazing, expressed as a
simple fraction or percentage
4.3
Site Sustainability
This Section deals with sites to ensure energy efficiency through passive and low energy
architectural features and management of resources.
4.3.1
Mandatory Unpaved Area
Fifty (50) percent of mandatory open space shall be permeable on sites of all occupancy
categories. The permeable area shall not remain bare generating dust, but will have green
cover or be treated with perforated paving (≥ 50%), organic mulch, charcoal, etc.
4.3.2
Site Drainage and Run-Off Coefficient
Designs shall indicate site drainage considerations along with flash flooding and erosion
prevention measures for sites above 1340 m2 in area. As excessive paving is largely
responsible for fast water run-off and flash flooding, design shall indicate measures taken
to make paving permeable. The net run-off from a site shall be a maximum of sixty (60)
percent. The following method will be used for the calculations, in conjunction with
Table 3.4.1:
Total Perviousness on Open Area of Site (Ap) = A1 x C1 + A2 x C2 + …
(3.4.1)
Where, A1, A2, etc., being the areas of various surfaces, e.g. Pavements, roads,
vegetation, etc., with different run-off coefficients C1, C2, C3 etc., shown in the Table
3.4.1.
4.3.3
Vegetation Plan
For sites above three (3) acres, it is mandatory for a vegetation plan to be submitted along
with the site plan and Irrigation Plan, where priority shall be given to native plants in the
selection for planting.
4.3.4
Irrigation Plan
4.3.4.1 For sites above ten (10) acres, an irrigation plan with construction details shall
be submitted with the site plan, where considerations shall include for management of rainwater.4.3.4.2 For these sites a retention pond of ≥ 3% of site area shall be provided. This shall
include any existing natural water body within the site. Table 3.4.1: Run-Off Coefficients of Various Surfaces Surface Type Run-Off Coefficient, C Roofs, conventional 0.95 Green Roofs (soil/growing medium depth ≥ 300 mm) 0.45 Concrete paving 0.95 Gravel 0.75 Brick paving 0.85 Vegetation: 1-3% 3-10%10%0.20 0.25 0.30 Turf Slopes: 0-1% 1-3% 3-10%
10%0.25 0.35 0.40 0.45 4.3.5 Rain Water Harvesting System
4.3.5.1 Buildings of total floor area > 4000 m2 shall have its own rain water harvesting
system as discussed in Chapter 7 Part 8 and installed complying with Section 7.13 Part 8, of this Code. The reservoir capacity shall be a multiple of the area of Ground Coverage of the building and a rain collection coefficient of 0.073.4.3.5.2 The rainwater reservoir may be placed under the roof or at lower levels,
including underground. 4.4 BUILDING ENVELOPE 4.4.1 Window to Wall Ratio4.4.1.1 For mechanically ventilated and cooled buildings of all occupancies, other than
Hazardous and Storage, the Window to Wall ratio of building (WWRB), will be determined in conjunction with the glazing performance, as indicated by the Solar Heat Gain Coefficient (SHGC) or Shading Coefficient (SC) of the glass used. The relationship is given in Figure 3.4.1 and Table 3.4.2. Figure 3.4.1 Selection of glazing SHGC based on WWR Table 3.4.2 Selection of Glazing SHGC Based on WWR in Tabular Format WWR SHGC SC 0.85 0.98 0.6 0.69 0.5 0.57 0.4 0.46 0.35 0.4 0.33 0.38 0.31 0.36 0.3 0.34 0.27 0.314.4.1.2 In all of the above cases, the Visible Light Transmittance (VLT) of the glazed
element shall not be lower than thirty five (35) percent.4.4.1.3 For Air-conditioned buildings with external shading, permitted SGHC limit may
be adjusted, but the increase shall not exceed values determined by Eq. 3.4.2 below: = + (3.4.2) Where, is the adjusted solar heat gain coefficient limit for windows with shading SHGC is the solar heat gain coefficient from Table 3.4.2 A is the SHGC correction factor for the external shading as per Table 3.4.3 or Table 3.4.4: For a window with overhang and fin, the value of A can be only used either from overhang or from fin.4.4.1.4 For naturally ventilated buildings, window size shall be based on Sec 4.4.2.
Window Openings of this Code and shading shall be provided as per Sec 4.4.3.4.4.1.5 Window size shall under no circumstances be less than as stipulated under Part
3: Chapter 1, Section 1.17 of this Code.
Table 3.4.3: Correction Factor against Overhang Shading Projection Factor
Overhang Projection Factor
SHGC Correction Factor(A)
0.0
0.00
0.1
0.05
0.2
0.09
0.3
0.14
0.4
0.19
0.5
0.24
0.6
0.28
0.7
0.33
0.8
0.38
0.9
0.43
1 or higher
0.47
Projection factor for overhang is the depth of the overhang divided
by the height of the window
Table 3.4.4: Correction Factor against Vertical Shading (fins) Projection Factor
Vertical Shading (Fins) Projection Factor
SHGC Correction Factor (A)
0.0
0.00
0.1
0.04
0.2
0.08
0.3
0.12
0.4
0.16
0.5
0.20
0.6
0.24
0.7
0.28
0.8
0.32
0.9
0.36
1 or higher
0.40
Projection factor of fins is the depth/length of fin divided by the width of the window.
4.4.2
Window Openings
Mechanically ventilated and cooled buildings of all occupancies, other than hazardous,
retail and storage, shall have the provision of using natural ventilation for cooling and
fresh air, in frequently occupied areas , with a fraction > 4% of the floor area being
specified as openable windows. Openable balcony doors can be counted in this
calculation. Note if the window area defined under Sec 4.4.1 is less than openable area,
then fifty (50) percent of window area should be openable.
4.4.2.1 Naturally ventilated buildings of all occupancies, other than hazardous and
storage, shall provide for fifty (50) percent of its window area to be openable.4.4.2.2 All the openable windows above ground should be designed with safety
measures in place such as protection hand rails for child safety.4.4.2.3 Windows to any regularly occupied space on exterior walls in naturally
ventilated buildings shall be shaded conforming to Sec 4.4.3. 4.4.3 Shading4.4.3.1 For naturally ventilated buildings of all occupancies, horizontal sunshades shall
be provided over windows on South, East and West, the depth of which shall be calculated by multiplying the window height with a factor of 0.234 (Figure 3.4.2). Horizontal louvers can be used instead of sunshades, in which case, depth of louver shall not be less than 0.234 times the gaps between the louvers (Figure 3.4.3).4.4.3.2 Vertical Shading devices shall be provided on the West, depth of which shall be
calculated, by multiplying the gaps between the vertical fins, or the window width if the shades border the window width, with a factor of 0.234 (Figure 3.4.4). Exceptions: (a) The above rule shall be relaxed if it can be demonstrated that shading is achieved by existing neighbouring structures. (b) The north side of all buildings are exempt from the above rules. Figure 3.4.2 Horizontal shade: x ≥ 0.234y Figure 3.4.3 Horizontal Louvres: relationship between depth (x) and gap (y): x ≥ 0.234y Figure 3.4.4 Vertical shading or louvres: relationship between depth (x) and gap (y): x ≥ 0.234y 4.4.4 Roof Insulation and Green Roofing System4.4.4.1 Fifty (50) percent of horizontal exposed roof slabs of Buildings of Occupancy
B, C, D and E, shall have green roofing system, to manage water run-off from roof tops, to control internal temperatures within the top floors and to reduce the carbon footprint of the building. This shall not include any covered roof surface, e.g. solar panels, solar thermal heaters, machinery for mechanical or electrical systems, water tanks, etc. Stair loft or machine room tops will be exempt from this rule. (a) The roof slab design shall consider structural support of the green roof system, with growing medium of minimum 300 mm. (b) The design will indicate protection from dampness and provide a drainage system4.4.4.2 Horizontal roof slabs, which are not covered by green roofing system, will have
roof slabs with insulation, so that the time lag and decrement factor is greater than the other floor slabs of the building. 4.5 Energy Efficient Building Systems 4.5.1 Daylighting and Supplementary Lighting System4.5.1.1 Window area shall not be less than 14 percent or 1/7th of the total floor area of
the building.4.5.1.2 Every regularly occupied space shall contain a minimum percentage of day-lit
area along the building perimeter zones, with no window less than an area of 1 m2 and will ensure the appropriate stipulations given below. (a) for rooms that measure less than 8 m in depth, window area shall be at least 20 percent of the area of the external wall of the room. (b) for rooms that measure between 8 to 14 m in depth, window area shall be at least 30 percent of the area of the external wall of the room and 35 percent of the external wall. (c) for rooms that measure more than 14 m in depth, window area shall be at least 35 percent of the area of the external wall of the room.4.5.1.3 For Buildings of Occupancy A5, B, C, E1 and E2, photoelectric sensors shall be
connected to luminaires, to enable dimming or switching off lamps that do not require to be operated, due to the presence of adequate daylight. The photoelectric sensor shall be located approximately at half (½) the depth of day-lit zone.4.5.1.4 If occupancy sensors are installed in the daylight area, the occupancy sensor
shall override the daylight sensor during non-occupancy period. Exceptions: (a) Zones with special requirements are exempt from the stipulation of Sec 4.5.1.3. The designer shall justify the reason for exemption. (b) Hotel guest rooms are exempt. 4.5.2 Lighting Power Density4.5.2.1 Lighting Power Density (LPD) of the values set in Table 3.4.5 shall be provided
for the respective functions within all building occupancies, or as specified.4.5.2.2 In addition to Sec 4.5.2.1, Illumination values (Lux) as specified in Tables 8.1.5
to 8.1.14 of Part 8 of this Code shall be provided for buildings of the respective occupancies. 4.5.3 Occupancy Sensors4.5.3.1 In order to limit the use of electricity in the unoccupied areas of buildings,
occupancy sensors linked to lighting (except for emergency and security lighting) shall be installed in the public areas of buildings of occupancies specified in Table 3.4.6. Table 3.4.5: Maximum Allowable Lighting Power Density for Different Occupancies Occupancy Maximum LPD (W/m2) E1 and E2 Offices F1 and F2 Retail/Mercantile A5 Hotels D1 Hospitals A1, A2 and A3 Apartments/residences B Educational All occupancies Covered parking* All occupancies Open/outdoor parking 1.6- LPD for car parks shall calculated from the total lighting power divided by the total car park area Table 3.4.6: Applicability of Occupancy Sensors Occupancy Applicability E1 and E2 Offices Meeting rooms and corridors A5 Hotels Meeting rooms and corridors A3 Apartments Covered car parks and corridors B Educational Covered car parks and corridors