Final Report Lot 9: Public street lighting - Amper

normalised eye sensitivity
1,0
0,8
0,6
0,4
0,2
0,0
scotopic photopic
380 430 480 530 580 630 680 730 780
wavelenght (nm)
Figure 17: Normalised eye sensitivity for scotopic and photopic vision.
Please note that the assessment of the advantages/disadvantages of more white light in road
lighting is complicated and subject of ongoing research studies (e.g. EU Growth Project
'MOVE: Mesopic Optimization of Visual Efficiency') coordinated by the CIE Technical
Committee on 'Visual Performance in the Mesopic Range' (1-58)).
By consequence, at low light levels or so called 'mesopic view conditions' and photometric
values such as lamp efficacy or luminance should be corrected (Narisada K. & D. Schreuder
(2004)) in function of colour and luminance level. Therefore the lamp efficacy should be
corrected for different lamp types when they have a different colour spectrum in function of
photopic luminance (see Table 21). Please note that Low Pressure Sodium lamps produce
orange light, Metal Halide lamps produce white light and High Pressure Sodium lamps appear
golden-white. The relationship with illuminance can also be derived when a reflection
coefficient for road objects is assumed (e.g. ρ =0.3) (Table 22). Therefore a relationship with
illuminance requirements in defined road classes (standard EN 13201-2) is possible.
Table 21: Corrections for lamp efficacy at mesopic luminance (Source: 'Opstelten, 1984 in
Narisada K. & D. Schreuder, 2004).
Photopic luminance(Cd/m²) 10 1 0.5 0.1 0.01 0.001
Lamp type
Lamp power
(W)
90
% apparent efficacy(lm/W)
Low Pressure Sodium (LPS) 90 100 96 95 75 34 24
High Pressure Sodium (HPS) 250 100 98 96 86 68 62
Metal Halide (MH) 400 100 103 105 116 138 144