Final Report Lot 9: Public street lighting - Amper

phase of the project can lead to important errors in road luminance after installation (-40 up to
60 %). In countries with wet climate this should be taken into account (more reflection).
Because of the wide variety of combinations, the best fit solution should, according to MG, be
part of a detailed photometric study.'
The lighting system is also linked to the electricity grid. The impact is limited to line voltage
variations (see also chapter 3) and separate grid shared with residential distribution grid. A
separate distribution grid offers more possibilities for telemanagement, switch off or dimming
systems.
Formulas related to energy efficiency at installation level:
To measure street lighting energy efficiency the parameter “Lighting Power Density” (LPD) is
introduced (see also reference (IEA (2006)).
For category F and M with luminance requirements:
LPDl [W/((cd/m²).m²)] = P / (L x A)
For category S with illuminance requirements:
LPDi [W/(lx.m²)] = P / (E x A)
Where,
• A is street area surface (m²) by multiplying street width with average distance between
light points. Street width includes also pedestrian and cyclists area (if any). Average
distance between light points is best determined by light points per km, since one pole
does not necessarily contain only one luminaire or one light point.
• E and L are defined in chapter 1.
As a consequence, the lighting power density can be calculated from the defined equipment
(lamp, ballast, luminaire) performance parameters:
LDPi [W/(lx.m²)] = 1 / {(UF x LMF) x (ηlamp x LLMF) x (ηballast)}
When taking into account the reflection of the road (parameter Q0 as defined in chapter 3) LPDl
can also be calculated:
LDPl [W/{(cd/m²).m²}] = LDPi x Q0
Where,
• Q0 is defined in chapter 3.
The real “Lighting Power Density” (LPDireal, LPDlreal) is related to the Lighting Power Density
(LPDl, LPDi) under standard conditions by:
and
LPDlreal [W/((cd/m²).m² )] = LPDl / (BMF x BGF x LGF)
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