Page 30 - GRIHA Manual Volume III - Introduction to National Rating System
P. 30
Building and system design optimization 23
The procedure adopted for daylight analysis is as follows.
1. Develop a 3D model of the building with proposed window (size and location) and shading
device (if any).
2. Assign specific building material properties of the internal space that have impact on daylight
distribution (such as visible light transmittance of glazing, internal reflectance of wall, ceiling,
floor, and so on).
3. Trace the calculated daylighted area (as per ECBC) on the floor with respect to the proposed
openings.
4. Draw the daylight grid on the daylighted area at a work plane height (750–900 mm from floor
finish).
5. Feed the date and time or the design sky condition in case the daylight level (lux) needs to be
calculated.
6. Run the software for daylight simulation and find the DF or daylight level at the centre of the
daylighted area or average on daylight grid.
7. Check whether the calculated DF meets the daylight requirements as specified in table 2
of SP41.
a. If it is fully met, then finalize all the window specifications (size, location, shading device,
glazing properties, and so on).
b. If it does not meet, then the window specifications need to be redefined or modified.
Example
Let us consider a sample building with following specifications.
# Type: Office building
# Location: Jaipur (design sky condition=10 500 to 11 000 lux)
# One floor plate for staff seating of area 16,000 mm × 8,000 mm × 3100 mm
# Four south-facing windows of area 3000 mm × 1500 mm with sill height 800 mm
# Proposed shading = one horizontal shading of 375 mm at lintel height
# Visible light transmittance (VLT) of proposed glazing = 40%
Figure 16 Average daylight level on daylight zone = 61 lux (not adequate)
The procedure adopted for daylight analysis is as follows.
1. Develop a 3D model of the building with proposed window (size and location) and shading
device (if any).
2. Assign specific building material properties of the internal space that have impact on daylight
distribution (such as visible light transmittance of glazing, internal reflectance of wall, ceiling,
floor, and so on).
3. Trace the calculated daylighted area (as per ECBC) on the floor with respect to the proposed
openings.
4. Draw the daylight grid on the daylighted area at a work plane height (750–900 mm from floor
finish).
5. Feed the date and time or the design sky condition in case the daylight level (lux) needs to be
calculated.
6. Run the software for daylight simulation and find the DF or daylight level at the centre of the
daylighted area or average on daylight grid.
7. Check whether the calculated DF meets the daylight requirements as specified in table 2
of SP41.
a. If it is fully met, then finalize all the window specifications (size, location, shading device,
glazing properties, and so on).
b. If it does not meet, then the window specifications need to be redefined or modified.
Example
Let us consider a sample building with following specifications.
# Type: Office building
# Location: Jaipur (design sky condition=10 500 to 11 000 lux)
# One floor plate for staff seating of area 16,000 mm × 8,000 mm × 3100 mm
# Four south-facing windows of area 3000 mm × 1500 mm with sill height 800 mm
# Proposed shading = one horizontal shading of 375 mm at lintel height
# Visible light transmittance (VLT) of proposed glazing = 40%
Figure 16 Average daylight level on daylight zone = 61 lux (not adequate)
