Illuminance and Uniformity

Illuminance and Uniformity

7 Illuminance and Uniformity

Table 2 shows the satisfactory ranges of average illuminance for various area floodlighting applications and Table 3 suggests limiting values for two alternative measures of overall uniformity, which are:

(a) the illuminance ratios,

(i) maximum to minimum values of illuminance

(ii) average to minimum values of illuminance

(b) the maximum rate of change of illuminance with distance.

Table 2 Illuminance Ranges Recommended for Exterior Lighting

Illuminance range, lux	Critical Plane	Application
1-10	Horizontal	Amenity General storage areas
	Vertical	Security Casual sport training
10-50	Horizontal	Stock and cargo handling Non-critical working areas Car parks
50 - 100	Horizontal	Critical working areas Sports practice Playgrounds
	Vertical	Aircraft service areas Advertising - unlit roads
100 - 500	Horizontal	Club and tournament sports Sales areas
	Vertical	Advertising - lit roads Spectator sports
500 - 1000	Vertical	International sports and lighting for colour TV

Table 3 Uniformity Recommendations for Exterior Lighting

Application	Uniformity of illuminance in critical plane of measurement		Minimum distance over which 20 % change in illuminance occurs, m
	max : min	av : min
Non-critical areas: parks, gardens, amenity lighting	50 : 1	-	-
Working areas Most building facades Sports training areas	20 : 1	10 : 1	2
Even lighting of plain light-coloured surfaces Spectator sports areas	10 : 1	5 : 1	3
Filming and television	3 : 1	1.5 : 1	4