Page 18 - GRIHA Manual Volume III - Introduction to National Rating System
P. 18
Building and system design optimization 11
exposed fenestrations of the building from direct solar exposure. Use of external shading devices
is the most effective way to prevent unwanted heat gain during summer. However, the shading
devices need to be optimized as per the solar angle, so that the shading device can keep the summer
sunlight out and allow the winter sunshine in.
The shading devices can be broadly categorized under the following three heads.
a) Horizontal type (H);
b) Vertical type (V); and
c) Mixed (M)—combination of types H and V
Note: Refer Annexure 2 for examples of different types of window shading.
Methods of shading design
There are various methods of designing appropriate shading devices for fenestrations. Two such
methods are as follows.
A. Sun path analysis
B. Use of shading norms (prescribed in the Handbook on Functional Requirements of Buildings
[Other than industrial buildings], part 4, table 9, and 10), and so on.
Sun path analysis
The main objective of sun path analysis is to find out critical window angles or shadow angles on
respective fenestrations in order to calculate the appropriate depth of shading devices. In order
to optimize the dimensions of the shading devices, the angle of incident radiation of the sun in
relation to the building elevation must be established for the given point. The angle of incidence on
the vertical surfaces is represented by the following two components.
1. Horizontal shadow angle (HSA)
2. Vertical shadow angle (VSA)
The performance of shading devices is specified by these two angles, and both of these are measured
from a line perpendicular to the elevation.
Note: Refer Annexure 3 for details of sun path diagram.
Horizontal shadow angle (HSA) characterizes a vertical shading device. It is the angle between
the wall normal and the line joining the outer edge of the vertical shade to the centre of the
wall normal.
exposed fenestrations of the building from direct solar exposure. Use of external shading devices
is the most effective way to prevent unwanted heat gain during summer. However, the shading
devices need to be optimized as per the solar angle, so that the shading device can keep the summer
sunlight out and allow the winter sunshine in.
The shading devices can be broadly categorized under the following three heads.
a) Horizontal type (H);
b) Vertical type (V); and
c) Mixed (M)—combination of types H and V
Note: Refer Annexure 2 for examples of different types of window shading.
Methods of shading design
There are various methods of designing appropriate shading devices for fenestrations. Two such
methods are as follows.
A. Sun path analysis
B. Use of shading norms (prescribed in the Handbook on Functional Requirements of Buildings
[Other than industrial buildings], part 4, table 9, and 10), and so on.
Sun path analysis
The main objective of sun path analysis is to find out critical window angles or shadow angles on
respective fenestrations in order to calculate the appropriate depth of shading devices. In order
to optimize the dimensions of the shading devices, the angle of incident radiation of the sun in
relation to the building elevation must be established for the given point. The angle of incidence on
the vertical surfaces is represented by the following two components.
1. Horizontal shadow angle (HSA)
2. Vertical shadow angle (VSA)
The performance of shading devices is specified by these two angles, and both of these are measured
from a line perpendicular to the elevation.
Note: Refer Annexure 3 for details of sun path diagram.
Horizontal shadow angle (HSA) characterizes a vertical shading device. It is the angle between
the wall normal and the line joining the outer edge of the vertical shade to the centre of the
wall normal.
