ABSTRACT
The notion of ordered distributions of illumination leads to the concept of illumination hierarchy, whereby illumination distributions are structured as a principal means by which the designer may express his or her design intentions. Such distributions are planned as changing balances of direct and indirect illumination, and are achieved by specifying target/ambient illuminance ratio (TAIR) values. The illumination hierarchy spreadsheet facilitates application of this concept. An ordered illumination distribution is the underpinning basis for structuring a lighting design concept. The designer selects target surfaces and designates values according to the level of perceived difference of illumination brightness to be achieved both between room surfaces, and between objects and the surroundings against which they are seen. While the perceived adequacy of illumination (PAI) criterion is concerned with ensuring adequate inter-reflected flux (MRSE) within a space, the illumination hierarchy criterion is concerned with how the direct flux from the luminaires may be distributed to create an ordered pattern of illumination.
