Final Report Lot 9: Public street lighting - Amper

Table 22: Relationship between photopic luminance and illuminance of road objects
calculated with 30 % reflection (formula see 1.2 ρ =0.3, R = 0.1 )
Photopic luminance(Cd/m²) 10 1 0.5 0.1 0.01 0.001
Illuminance (lx) with ρ =0.3 100 10 5 1 0.1 0.01
Conclusions related to this study are:
- Metal halide lamps or white light lamps have an advantage in apparent luminance compared to
High Pressure Sodium when photopic road illuminance (Table 22) is low ( +10 % at 5 lx and
+30 % at 1 lx). Please note that there are many new colour blends in High Pressure Sodium
lamps, by consequence this advantage will only be allocated +10 % for road classes S5 (3 lx)
and +15 % for road classes S6.
- White light can decrease the contrast between road objects at high photopic luminance levels
(e.g. 1 Cd/m² in Table 22) versus the road surroundings at much lower level (e.g. 0.1 Cd/m² in
Table 22).
- White light has an increased contribution to visible (human) 'sky glow' because sky glow
luminance is around 0.001 Cd/m² (Narisada K. & D. Schreuder (2004)). This effect on light
pollution is not considered neither here nor below in LGF because of the reasons explained in
section 4.3.1.3.
- It is also not recommended to overly promote white light at road classes above S5 and S6 (EN
13201-2) because insects are more attracted (Steck, B. (1997)) by blue light and UV. By
consequence luminaires with white light that have blue light as colour component (e.g. High
Pressure Mercury or Metal Halide lamps) will also become more polluted by insects than
luminaires with golden white light (e.g. High Pressure Sodium). Especially UV attracts insects
(Steck, B. (1997)). High Pressure Mercury lamps have a high UV content and are therefore not
recommended in open luminaires.
For judging improvement options in different road classes with different lighting requirements
we can take into account a correction factor for lamp efficacy (Lamp Gain Factor, LGF).
Table 23: Lamp Gain Factor (LGF): parameter values applied in this study according to
road class category distinguished in EN 13201-2
Road class (EN 13201-2) LGF
S6 (2 lx) 1.2
S5 (3 lx) 1.1
All other 1
3.1.2 Influence of user and local conditions on switching schemes
Globally the dark period is 4000 h per year. Seasonal changes between winter and summer
increase with distance from the equator. Nordic countries have daylight during almost the
whole day in summer and are dark (almost) all day in winter. At equinox (21 March and 21
September) day and night are equal everywhere over the globe. By consequence 4000 operating
hours per year (as suggested by ELC and found in different literature sources) is the universal
default value for street lighting.
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