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BEAM P
LUS FOR
N
EW
B
UILDINGS
S
ITE
A
SPECTS
(S
A
)
V
ERSION
1.2
S
A
15 L
IGHT
P
OLLUTION
Copyright © 2012 BEAM Society Limited. All rights reserved.
Page 60
The brightness of advertising signs is also a concern [6].The following
table is taken from CIBSE Factfile 7 [2] :
The definitions of the four zones are:
E1: Intrinsically dark areas: National Parks, Areas of Outstanding Natural
Beauty, etc.
E2: Low district brightness areas: rural or small village locations.
E3: Medium district brightness areas: small town centres or urban locations.
E4: High district brightness areas: town/city centres with high levels of night-time
activity.
ULR = Upward Light Ratio of the Installation and is the maximum permitted
percentage of luminaire flux for the total installation that goes directly into
the sky.
Ev = Vertical Illuminance in Lux normal to window glazing
I = Light Intensity in Kilo-Candelas
L = Luminance in Candelas per Square Metre
Notes:
(1) These values are suggested maximums for any window. So any new lighting
will have to produce less than this value if there is any existing light trespass at a
specific window.
(2) This is the intensity going beyond the area being lit from any single source in
the potentially obtrusive direction. The figures given are for general guidance
only and for some large sports lighting applications with limited mounting heights
may be difficult to achieve.
(3) This should be limited to avoid over lighting, and relates to the general district
brightness. In this reference building luminance is applicable to buildings directly
illuminated as a night-time feature as against the illumination of a building caused
by spill light from adjacent floodlights or floodlights fixed to the building but used
to light an adjacent area although this should be kept to a minimum.
(4) Acceptable from public road lighting and other safety lighting installations
only, zero for all other lighting types.
Obtrusive light limitations for exterior lighting installations
Environmental
Zone
Sky Glow
ULR (Max
%)
Light into Windows
Ev (Lux) (1)
Source Intensity I
(kcd) (2)
Building Luminance
Before curfew (3)
Before
curfew
After
curfew
Before
curfew
After
curfew
Average L (cd/m
2
)
E1
0
2
1(4)
2.5
0.5 (4)
0
E2
2.5
5
1
7.5
0.5
5
E3
5
10
2
10
1
10
E4
15
25
5
25
2.5
25
6
The Institution of Lighting Engineers. Brightness of Illuminated Advertisements. Technical Report No.5, 2001.