If the overall distribution of
daylight in a room is to be predicted, the best method is to set out a grid and calculate
the SC and ERC for each of the grid-points. The average IRC can then be found, corrected
by factor D, and added to each value, after which the factors M, G and B can be applied.
By interpolating between grid-point values, a set of daylight factor contours can be
drawn, indicating the distribution of daylight.