Page 14 - GRIHA Manual Volume III - Introduction to National Rating System
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Building and system design optimization 7
The best orientation from a solar radiation point of view requires that the building, as a whole,
should receive maximum solar radiation in winter and minimum in summer. For practical evaluation,
it is necessary to know the duration of sunshine, and hourly solar intensity on various external
surfaces during representative days of the seasons. The total incident solar radiation per unit area
on vertical as well as horizontal surfaces are shown in Table 1 for two days of the year, namely,
22 June and 22 December, representative of summer and winter solstice respectively, for latitudes
corresponding to some important cities of India.
From table 1, it can be observed that in summer the total incident solar radiation is maximum on
horizontal surface (that is, roof, open terrace, open courtyard, and so on). Among the façades, the
western and eastern ones are more critical in summer as compared to the southern and northern
façades. But in winters, the maximum incident solar radiation is on the southern surface, which is
always allowable inside the building.
Table 1 Total solar radiation (direct plus diffused) incident on various surfaces of buildings in W/m /day for summer and winter
2
(Clause 3.4.1)
Orientation Latitude
9º N 13º N 17º N 21º N 25º N 29º N
(1) (2) (3) (4) (5) (6) (7) (8)
North Summer 1494 1251 2102 1775 2173 1927
Winter 873 859 840 825 802 765
North-East Summer 2836 2717 3144 3092 3294 3189
Winter 1240 1158 1068 1001 912 835
East Summer 3344 3361 3475 3598 3703 3794
Winter 2800 2673 2525 2409 2211 2055
South-East Summer 2492 2660 2393 2629 2586 2735
Winter 3936 3980 3980 3995 3892 3818
South Summer 1009 1185 1035 1117 1112 1350
Winter 4674 4847 4958 5059 4942 4981
South-West Summer 2492 2660 2393 2629 2586 2735
Winter 3936 3980 3980 3995 3892 3818
West Summer 3341 3361 3475 3598 3703 3794
Winter 2800 2673 2525 2409 2211 2055
North-West Summer 2836 2717 3144 3092 3294 3189
Winter 1240 1158 1068 1001 912 835
Horizontal Summer 8107 8139 8379 8553 8817 8863
Winter 6409 6040 5615 5231 4748 4281
Source Table-3, National Building Code-2005
The best orientation from a solar radiation point of view requires that the building, as a whole,
should receive maximum solar radiation in winter and minimum in summer. For practical evaluation,
it is necessary to know the duration of sunshine, and hourly solar intensity on various external
surfaces during representative days of the seasons. The total incident solar radiation per unit area
on vertical as well as horizontal surfaces are shown in Table 1 for two days of the year, namely,
22 June and 22 December, representative of summer and winter solstice respectively, for latitudes
corresponding to some important cities of India.
From table 1, it can be observed that in summer the total incident solar radiation is maximum on
horizontal surface (that is, roof, open terrace, open courtyard, and so on). Among the façades, the
western and eastern ones are more critical in summer as compared to the southern and northern
façades. But in winters, the maximum incident solar radiation is on the southern surface, which is
always allowable inside the building.
Table 1 Total solar radiation (direct plus diffused) incident on various surfaces of buildings in W/m /day for summer and winter
2
(Clause 3.4.1)
Orientation Latitude
9º N 13º N 17º N 21º N 25º N 29º N
(1) (2) (3) (4) (5) (6) (7) (8)
North Summer 1494 1251 2102 1775 2173 1927
Winter 873 859 840 825 802 765
North-East Summer 2836 2717 3144 3092 3294 3189
Winter 1240 1158 1068 1001 912 835
East Summer 3344 3361 3475 3598 3703 3794
Winter 2800 2673 2525 2409 2211 2055
South-East Summer 2492 2660 2393 2629 2586 2735
Winter 3936 3980 3980 3995 3892 3818
South Summer 1009 1185 1035 1117 1112 1350
Winter 4674 4847 4958 5059 4942 4981
South-West Summer 2492 2660 2393 2629 2586 2735
Winter 3936 3980 3980 3995 3892 3818
West Summer 3341 3361 3475 3598 3703 3794
Winter 2800 2673 2525 2409 2211 2055
North-West Summer 2836 2717 3144 3092 3294 3189
Winter 1240 1158 1068 1001 912 835
Horizontal Summer 8107 8139 8379 8553 8817 8863
Winter 6409 6040 5615 5231 4748 4281
Source Table-3, National Building Code-2005
