Illuminance and Uniformity
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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