Page 74 - GRIHA Manual Volume III - Introduction to National Rating System
P. 74
Building and system design optimization 67
Air-side economizers: Air-side economizers help in saving energy in buildings. Here, outside
air with lower enthalpy than inside air is used to cool building spaces. When the outside air is
sufficiently cool—so that no additional conditioning of it is needed—this portion of the air-
side economizer control scheme is called free cooling. Air-side economizers can reduce HVAC
energy costs in cold and temperate climates, while they potentially improve indoor-air quality.
However, these are quite often not appropriate in hot and humid climates.
Water-side economizers: They are used when the outside air is dry and wet-bulb temperatures
are low. They use water cooled by a wet cooling tower to cool buildings without operating
a chiller. In place of conventional heat exchanger coils, these use a plate-and-frame heat
exchanger, which is inserted between the cooling tower and chilled water loops.
Good control, and valves or dampers, as well as maintenance are needed to ensure proper
operation of the air- and water-side economizers.
• Variable Frequency Drives
Variable Frequency Drives (VFD) are installed in AHUs. The VFD varies the speed of the fan
according to the return air temperature (temperature of the air, which comes from the
conditioned spaces), which in turn controls the flow of air.
GRIHA-speciic information
Objective
To optimize use of energy systems in buildings that maintain a specified indoor climate
conducive to the functional requirements of the buildings.
14.1 Commitment
14.1.1 Follow mandatory compliance measures (for all applicable buildings) as recommended
in the ECBC-2007 of the BEE, Government of India.
14.1.2 Perform hourly calculations to show that in air-conditioned areas, the thermal comfort
conditions as specified in National Building Code 2005, BIS, are met for 100% of all
occupied hours.
Table 14.1 Inside design conditions for different spaces of buildings to meet thermal comfort standards
Sr. No. Category Inside design conditions
Summer Winter
(1) (2) (3) (4)
DB 23°C–26°C DB 21°C–23°C
1 Restaurants
RH 55%–60% RH not less than 40%
DB 23°C–26°C DB 21°C–23°C
2 Ofice buildings
RH 50%–60% RH not less than 40%
DB 21°C–23°C
3 Radio and television DB 23°C–26°C RH not less than 40%
studios
RH 45%–55%
Air-side economizers: Air-side economizers help in saving energy in buildings. Here, outside
air with lower enthalpy than inside air is used to cool building spaces. When the outside air is
sufficiently cool—so that no additional conditioning of it is needed—this portion of the air-
side economizer control scheme is called free cooling. Air-side economizers can reduce HVAC
energy costs in cold and temperate climates, while they potentially improve indoor-air quality.
However, these are quite often not appropriate in hot and humid climates.
Water-side economizers: They are used when the outside air is dry and wet-bulb temperatures
are low. They use water cooled by a wet cooling tower to cool buildings without operating
a chiller. In place of conventional heat exchanger coils, these use a plate-and-frame heat
exchanger, which is inserted between the cooling tower and chilled water loops.
Good control, and valves or dampers, as well as maintenance are needed to ensure proper
operation of the air- and water-side economizers.
• Variable Frequency Drives
Variable Frequency Drives (VFD) are installed in AHUs. The VFD varies the speed of the fan
according to the return air temperature (temperature of the air, which comes from the
conditioned spaces), which in turn controls the flow of air.
GRIHA-speciic information
Objective
To optimize use of energy systems in buildings that maintain a specified indoor climate
conducive to the functional requirements of the buildings.
14.1 Commitment
14.1.1 Follow mandatory compliance measures (for all applicable buildings) as recommended
in the ECBC-2007 of the BEE, Government of India.
14.1.2 Perform hourly calculations to show that in air-conditioned areas, the thermal comfort
conditions as specified in National Building Code 2005, BIS, are met for 100% of all
occupied hours.
Table 14.1 Inside design conditions for different spaces of buildings to meet thermal comfort standards
Sr. No. Category Inside design conditions
Summer Winter
(1) (2) (3) (4)
DB 23°C–26°C DB 21°C–23°C
1 Restaurants
RH 55%–60% RH not less than 40%
DB 23°C–26°C DB 21°C–23°C
2 Ofice buildings
RH 50%–60% RH not less than 40%
DB 21°C–23°C
3 Radio and television DB 23°C–26°C RH not less than 40%
studios
RH 45%–55%
