Page 78 - GRIHA Manual Volume III - Introduction to National Rating System
P. 78
Building and system design optimization 71
Methodology
Step 1: Calculating benchmark energy consumption index (EPI)
Identify the air-conditioned and non-air-conditioned building areas, and depending on the type of
spaces the building has and building operating hours, calculate the EPI benchmark of the building.
Following options are possible.
# If building contains only air-conditioned areas: Depending on the operating hours of the
building, take the EPI benchmark value mentioned in table 14.3 of GRIHA Criterion 14.
# If building contains only non-air-conditioned areas: Depending on the operating hours of the
building, take the EPI benchmark value mentioned in table 14.4 of GRIHA Criterion 14.
# If building contains both air-conditioned and non-air-conditioned areas: Depending on the
operating hours of the building, calculate the EPI benchmark value using the procedure given
in table 14.5 of GRIHA Criterion 14.
In case the building operating hours differ from that mentioned in table 14.1 of GRIHA Criterion 14
(for example a building that operates for 10 hours daily for six days a week), the following procedure
should be adopted for calculating the EPI benchmark of the building.
# Check the given operating hours of the building and see if it is closer to the ‘9 a.m.–5 p.m.
for 5 days a week’ category or ‘24 hours for 7 days a week’ category. Whichever category is
closer, the EPI benchmark value for that category is taken. For example, a building where the
working hours are 10 hours daily for 6 days a week, is closer to ‘9 a.m.–5 p.m. for 5 days a week’
category than ‘24 hours for 7 days a week’ category. So, in this case, the EPI benchmark value for
‘9 a.m.–5 p.m. for 5 days a week’ category should be used for the applicable climate type.
# Using the simulation software, the actual EPI of the building is also calculated by feeding in the
actual operating schedule of the building (10 hours daily for 6 days a week, in this case). This
actual EPI value is calculated for comparison with the EPI values calculated during the post-
occupancy audit of the building at a later stage.
Step 2: Check if ECBC mandatory compliances are met
Next step is to check that the project meets all the mandatory compliances of ECBC-2007. Six
mandatory points are achieved when all the mandatory compliances of ECBC-2007 are met in the
project.
Step 3: Calculate the annual energy consumption data for the building and
check if the required thermal comfort conditions are being met
A whole building performance approach is recommended for achieving compliance under GRIHA.
Appropriate standard building energy simulation software should be chosen and hourly calculations
should be performed.
Characteristics of thermal simulation software
The standard simulation building software should have the following features.
# Hourly values of climate data such as dry bulb temperature, wet bulb temperature, relative
humidity, wind velocity, total solar radiation, direct solar radiation, and so on, are used for
simulation. Generate an hourly weather file using weather data, acceptable by ISHRAE.
Methodology
Step 1: Calculating benchmark energy consumption index (EPI)
Identify the air-conditioned and non-air-conditioned building areas, and depending on the type of
spaces the building has and building operating hours, calculate the EPI benchmark of the building.
Following options are possible.
# If building contains only air-conditioned areas: Depending on the operating hours of the
building, take the EPI benchmark value mentioned in table 14.3 of GRIHA Criterion 14.
# If building contains only non-air-conditioned areas: Depending on the operating hours of the
building, take the EPI benchmark value mentioned in table 14.4 of GRIHA Criterion 14.
# If building contains both air-conditioned and non-air-conditioned areas: Depending on the
operating hours of the building, calculate the EPI benchmark value using the procedure given
in table 14.5 of GRIHA Criterion 14.
In case the building operating hours differ from that mentioned in table 14.1 of GRIHA Criterion 14
(for example a building that operates for 10 hours daily for six days a week), the following procedure
should be adopted for calculating the EPI benchmark of the building.
# Check the given operating hours of the building and see if it is closer to the ‘9 a.m.–5 p.m.
for 5 days a week’ category or ‘24 hours for 7 days a week’ category. Whichever category is
closer, the EPI benchmark value for that category is taken. For example, a building where the
working hours are 10 hours daily for 6 days a week, is closer to ‘9 a.m.–5 p.m. for 5 days a week’
category than ‘24 hours for 7 days a week’ category. So, in this case, the EPI benchmark value for
‘9 a.m.–5 p.m. for 5 days a week’ category should be used for the applicable climate type.
# Using the simulation software, the actual EPI of the building is also calculated by feeding in the
actual operating schedule of the building (10 hours daily for 6 days a week, in this case). This
actual EPI value is calculated for comparison with the EPI values calculated during the post-
occupancy audit of the building at a later stage.
Step 2: Check if ECBC mandatory compliances are met
Next step is to check that the project meets all the mandatory compliances of ECBC-2007. Six
mandatory points are achieved when all the mandatory compliances of ECBC-2007 are met in the
project.
Step 3: Calculate the annual energy consumption data for the building and
check if the required thermal comfort conditions are being met
A whole building performance approach is recommended for achieving compliance under GRIHA.
Appropriate standard building energy simulation software should be chosen and hourly calculations
should be performed.
Characteristics of thermal simulation software
The standard simulation building software should have the following features.
# Hourly values of climate data such as dry bulb temperature, wet bulb temperature, relative
humidity, wind velocity, total solar radiation, direct solar radiation, and so on, are used for
simulation. Generate an hourly weather file using weather data, acceptable by ISHRAE.
