Utilance values and uniformity in a model room

Abstract

A model room is described in which utilance values were measured for four different types of luminaire in rooms with a 'standard' set of reflectances, for a series of room index values. The measured values are within 10% of those calculated from the finite difference equation method. The IES method for measuring average illuminance was checked and the results shown to be generally satisfactory. Some measurements of luminance were made and the results show that the simple method of luminance calculation based on the assumption of uniform diffusion gives relatively small errors even for gloss painted walls, except where the luminaires are highly directional. Measurements of uniformity suggest that minimum/average is a less exacting criterion than that of minimum/maximum.