This standard provides a methodology for calculating the solar radiation incident on building surfaces. It includes fundamental formulas for solar angles, components of solar radiation (direct, diffuse, reflected), and provides tabulated climatic data for 14 major Indian cities to aid in design.
Recommendations for calculation of solar radiation on buildings
Quick Reference Values
Solar Constant1353 W/m²
Albedo of fresh snow0.80 to 0.85
Albedo of light colored concrete0.30 to 0.35
Albedo of green grass0.20 to 0.25
Atmospheric turbidity coefficient (B) for Industrial Atmosphere0.10
Atmospheric turbidity coefficient (B) for Clean Atmosphere0.05
Key Formulas
sin α = sin L sin δ + cos L cos δ cos h — Solar altitude angle (α)
sin γ = cos δ sin h / cos α — Solar azimuth angle (γ)
IT = IDN cos θ + Id + IR — Total solar radiation on a surface
Practical Notes
The climatic data in Annex A is from before 1986. For accurate energy simulations, it is highly recommended to use recent Typical Meteorological Year (TMY) or weather data files for the specific location.
This code forms the basis for calculating Solar Heat Gain Coefficient (SHGC) and thermal performance of building envelopes as required by the National Building Code (NBC) and Energy Conservation Building Code (ECBC).
Be careful with the sign conventions and definitions for angles (e.g., solar azimuth, wall azimuth) as they are critical for correct calculations.