The luminaire domain and the flow of light

The distributive principle is inapplicable to loci of scalar utilance and cylindrical utilance. The British Zonal classification system therefore cannot be used for predicting these quantities; despite this limitation it is concluded that a more widely applicable system of luminaire classification would be unacceptably complicated. Nomogram grids are presented which enable lines of limiting vector/ scalar ratio to be drawn on luminaire domain charts. Every locus of constant vector/scalar ratio in the luminaire domain is also a line of constant wall/task illuminance ratio and a line of constant horizontal/cylindrical illuminance ratio. In a given interior these ratios cannot be independent criteria; each can be expressed in terms of either of the others.