Civil Engineering Reference
In-Depth Information
16.1
Parameter Categories
The lighting parameters can be divided into those directly related to the light leaving
the location being lighted, i.e. installation-bound parameters, and those directly
related to the light arriving at the point of disturbance, i.e. disturbed area-bound
parameters. CIE uses a mix of both parameter categories for the limitation of light
pollution whereas IDA-IESNA uses solely parameters related to the light leaving
the location. Using solely installation-bound parameters has the advantage that no
information is needed concerning the location of areas where disturbance may arise.
On the other hand, people who are disturbed by light pollution may want to check,
from their own premises, whether or not a neighbouring lighting installation does
indeed exceed the disturbance limits. In the case of disturbed-area-bound parameters,
it is possible to design an installation in such a way that minimum disturbance in a
possible extra-critical direction is at minimum.
A method for the restriction of all aspects of light pollution with the sole use
of installation-bound parameters has been developed by Brons et al. (
2008
). Their
OSP (Outdoor Site-lighting Performance) method uses a calculation box that en-
closes the lighting installation along its property borders. The limiting parameters
used are the illuminances on the six planes of this, virtual, box. The IDA-IESNA
recommendations, as will be described in Sect. 16.2.2, are partly based on this
method.
16.2
Installation-Bound Parameters
16.2.1
Parameters used by CIE
16.2.1.1
Upward Light Ratio ULR
The parameters used for the limitation of upward light, and thus for the limitation of
sky glow, are all directly related to the light leaving the area to be lit. The upward
light ratio ULR is the proportion of the luminous flux of a luminaire or of all the
luminaires of an installation that is emitted at and above the horizontal, with the
luminaire(s) as mounted (tilted) in the installation (Fig.
16.1
):
∅
lum up
∅
lumtot
ULR
=
ULR does not take into account the effect of light reflected upwards from the illu-
minated surfaces. This is because ULR is a luminaire related criterion instead of an
installation related one.
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