Sky component for unglazed vertical rectangular opening Ds -- Algorithm 2.32

This algorithm gives the sky component (from a CIE overcast sky) on a horizontal plane due to an unglazed vertical rectangular opening which has its lower edge in the reference plane and one vertical edge in a plane perpendicular to the opening and containing the reference point.

Input

Angles a, b and c from figure above radians

Equation

Note

When the opening is H high, W wide and a perpendicular distance D away from the reference point,

To obtain the sky component for a opening with clear 6mm glass, the value Ds obtained from this algorithm may be multiplied by the transmittance T obtained from algorithm 2.34.

Source

Walsh(1)

References

1. Walsh J W T The science of daylight (London: Macdonald) (1961)