Page 28 - GRIHA Manual Volume III - Introduction to National Rating System
P. 28
Building and system design optimization 21
(b) Vertical fenestration (window): The daylighted area under vertical fenestrations extends to the
floor plate perpendicular to the side aperture, as demonstrated in figure 16 below.
Figure 16 Total daylighted area for window = 2H × (W + 2m)
Source ECBC-2007
b. Living area
Living area is defined as the functional area or full-time occupied area of the building that needs
daylight for various activities. Total built-up area of the building is not equal to the total living area.
The percentage of daylighted area is calculated by dividing the daylighted area by the total living
area of the proposed building. Therefore, first the living area needs to be identified before defining
the daylight zone. GRIHA has standardized the definition of living area as per SP41. Table 2 (part 4)
of SP41 highlights the types of living spaces followed by respective building types that are specified
from the daylight requirement point of view. Therefore, as per the daylight clause, the living area is
limited to only those categories of spaces that are specified in the table 13.2 of GRIHA Criterion 13
or spaces with similar activities. Therefore, the recommended daylight factor and the percentage of
daylighted area are calculated only for those categories of living spaces that are listed in the table
13.2 of GRIHA Criterion 13 or for spaces of similar activities.
Note: This daylight clause is non-mandatory for the type of buildings or the type of living spaces that are not listed in the
table 13.2 of GRIHA Criterion 13. However, those buildings can apply for the entire clause in order to get all the points as
an additional compliance. In this case, living space can be defined as per the project-specific daylight requirement.
c. Recommended daylight factor
Daylight factor (DF) is the quantification of available daylight inside a building with respect to the
outside illuminance. DF is defined as the percentage ratio of the daylight illuminance at an indoor
point on the working plane to the simultaneous outdoor illuminance on a horizontal plane due to
whole of the sky vault, excluding the direct sunlight. For the clear design sky, the DF is a percentage
fraction of outdoor illuminance.
DF = Ei × 100%
Eo
Where
Ei = illumination indoors at the point of observation (lux)
Eo = illumination outdoors from an unobstructed sky hemisphere (lux)
(b) Vertical fenestration (window): The daylighted area under vertical fenestrations extends to the
floor plate perpendicular to the side aperture, as demonstrated in figure 16 below.
Figure 16 Total daylighted area for window = 2H × (W + 2m)
Source ECBC-2007
b. Living area
Living area is defined as the functional area or full-time occupied area of the building that needs
daylight for various activities. Total built-up area of the building is not equal to the total living area.
The percentage of daylighted area is calculated by dividing the daylighted area by the total living
area of the proposed building. Therefore, first the living area needs to be identified before defining
the daylight zone. GRIHA has standardized the definition of living area as per SP41. Table 2 (part 4)
of SP41 highlights the types of living spaces followed by respective building types that are specified
from the daylight requirement point of view. Therefore, as per the daylight clause, the living area is
limited to only those categories of spaces that are specified in the table 13.2 of GRIHA Criterion 13
or spaces with similar activities. Therefore, the recommended daylight factor and the percentage of
daylighted area are calculated only for those categories of living spaces that are listed in the table
13.2 of GRIHA Criterion 13 or for spaces of similar activities.
Note: This daylight clause is non-mandatory for the type of buildings or the type of living spaces that are not listed in the
table 13.2 of GRIHA Criterion 13. However, those buildings can apply for the entire clause in order to get all the points as
an additional compliance. In this case, living space can be defined as per the project-specific daylight requirement.
c. Recommended daylight factor
Daylight factor (DF) is the quantification of available daylight inside a building with respect to the
outside illuminance. DF is defined as the percentage ratio of the daylight illuminance at an indoor
point on the working plane to the simultaneous outdoor illuminance on a horizontal plane due to
whole of the sky vault, excluding the direct sunlight. For the clear design sky, the DF is a percentage
fraction of outdoor illuminance.
DF = Ei × 100%
Eo
Where
Ei = illumination indoors at the point of observation (lux)
Eo = illumination outdoors from an unobstructed sky hemisphere (lux)
