scope:

The two linked Digests (309 and 310) present daylight prediction methods that can be used as a first stage in assessing the visual and energy impacts of window design and the effectiveness of daylight-linked lighting controls. Part 1 (Digest 309) covers the calculation of sky component and externally-reflected component.

Part 2 (DG310 - now out of print, but available as a pdf) deals with the internally-reflected component and corrections (for glazing, maintenance, etc) to the total daylight factor, and the calculation of average daylight factor.