Page 65 - GRIHA Manual Volume III - Introduction to National Rating System
P. 65
58 GRIHA Manual: Volume 3
Strategies for reducing EPI and maintaining required thermal comfort in
non-AC spaces
Demand reduction strategies
# Shading: In non-air-conditioned spaces, the fenestrations should be designed such that they
are fully shaded. Shading the openings help in reducing heat gain inside the building. Since
windows are operable in non-air-conditioned spaces, the SHGC calculations should be carried
out for clear glass or glass with SHGC of 1 and sufficient shading should be provided for meeting
the SHGC requirements as mentioned in ECBC-2007. For further description of this topic, refer
to GRIHA manual, Criterion 13.
# Insulation: Insulating the envelope assists in reducing heat gains inside the building. Insulating
the roof plays an important role in reducing heat gains inside the building as maximum heat
gain occurs through the roof. Use of insulation in walls is dependent on its impact on the
internal thermal comfort conditions.
# Lighting (LPD reduction strategies): Manual methods of lighting design may result in low
illumination levels in spaces that reduce the productivity of the occupants. A lighting system
design is considered effective and energy-efficient if the visual comfort, as specified by NBC-
2
2005 as well as the lighting power density LPD (W/m ) requirements as specified by ECBC-
2007, are met. Some of the differences between a conventional design and an energy-efficient
design have been demonstrated in table 4 below.
Table 4 Major differences between conventional and energy-eficient lighting design
Sl. No. Conventional lighting system Energy-eficient lighting system
1 Energy-ineficient ixtures Energy-eficient ixtures
Energy-ineficient lamps (40 W tube lights with magnetic Energy-eficient lamps (28 W tube lights with electronic
chokes, incandescent bulbs) chokes, CFLs)
2 No daylight integration Artiicial and daylight integration
3 Lighting power density (LPD) = 21 W/m 2
Lighting Power Density (LPD) = 10.8 W/m 2
4 No controls Occupancy sensors, continuous dimming sensors
Cooling strategies
There are various strategies that can be adopted for complying with the thermal comfort conditions
while ensuring energy efficiency. Some of these strategies have been described as follows.
1. Night ventilation
2. Evaporative cooling
3. Earth air tunnel system
4. Geothermal heat pump
Night purging (ventilation)
Night purging is a cooling strategy that uses the natural variations in day and night time temperature.
Night cooling is an effective strategy to be adopted in locations where there is significant difference
between the daytime and nighttime temperatures. In this process, a building is ventilated during
Strategies for reducing EPI and maintaining required thermal comfort in
non-AC spaces
Demand reduction strategies
# Shading: In non-air-conditioned spaces, the fenestrations should be designed such that they
are fully shaded. Shading the openings help in reducing heat gain inside the building. Since
windows are operable in non-air-conditioned spaces, the SHGC calculations should be carried
out for clear glass or glass with SHGC of 1 and sufficient shading should be provided for meeting
the SHGC requirements as mentioned in ECBC-2007. For further description of this topic, refer
to GRIHA manual, Criterion 13.
# Insulation: Insulating the envelope assists in reducing heat gains inside the building. Insulating
the roof plays an important role in reducing heat gains inside the building as maximum heat
gain occurs through the roof. Use of insulation in walls is dependent on its impact on the
internal thermal comfort conditions.
# Lighting (LPD reduction strategies): Manual methods of lighting design may result in low
illumination levels in spaces that reduce the productivity of the occupants. A lighting system
design is considered effective and energy-efficient if the visual comfort, as specified by NBC-
2
2005 as well as the lighting power density LPD (W/m ) requirements as specified by ECBC-
2007, are met. Some of the differences between a conventional design and an energy-efficient
design have been demonstrated in table 4 below.
Table 4 Major differences between conventional and energy-eficient lighting design
Sl. No. Conventional lighting system Energy-eficient lighting system
1 Energy-ineficient ixtures Energy-eficient ixtures
Energy-ineficient lamps (40 W tube lights with magnetic Energy-eficient lamps (28 W tube lights with electronic
chokes, incandescent bulbs) chokes, CFLs)
2 No daylight integration Artiicial and daylight integration
3 Lighting power density (LPD) = 21 W/m 2
Lighting Power Density (LPD) = 10.8 W/m 2
4 No controls Occupancy sensors, continuous dimming sensors
Cooling strategies
There are various strategies that can be adopted for complying with the thermal comfort conditions
while ensuring energy efficiency. Some of these strategies have been described as follows.
1. Night ventilation
2. Evaporative cooling
3. Earth air tunnel system
4. Geothermal heat pump
Night purging (ventilation)
Night purging is a cooling strategy that uses the natural variations in day and night time temperature.
Night cooling is an effective strategy to be adopted in locations where there is significant difference
between the daytime and nighttime temperatures. In this process, a building is ventilated during
