Technical information
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Recommended luminance conditions between the working area and the room’s surfaces
Light planning
Instructions for planning and calculations
The luminance ratio between the working area and the wall should not be less than 5:1. With indirect lighting the average luminance on the ceiling should not exceed 500 cd/m².
Room surface Recommended
reflectance
Relative
illuminance
Ceiling 0.6–0.9 0.2–0.9
Walls 0.3–0.8 0.2–0.6
Window wall > 0.6 0.3–0.6¹⁾
Workspaces 0.2–0.6 1.0–
Floor 0.1–0.5
¹⁾ The values apply in daylight – without daylight the relative illuminance should not
exceed 0.2 provided that the glazed surfaces do not have bright curtains.
The luminance from the room’s surfaces must be relative to the lu-
minance from the working plane, in order to conform to EN 12464-1
demands. For example, when using low luminance luminaires and
downlights, there is a risk that the tops of the walls and the ceiling,
may be too dark.
The dierence in luminance can be calculated or measured as a
relation between dierent surface luminances. The following lumi-
nance conditions are recommended for the workplace:
The working area (inner eld of vision) – immediate surroundings •
(the near eld) 3:1.
The working area (inner eld of vision) – surroundings (adjacent •
walls within the eld of vision) 5:1.
The working area (inner eld of vision) – periphery wall surfaces •
(background) 10:1.
Later studies, however, show that the luminance relationship be-
tween the working area and the ambient area (wall surface) should
be 2:1 with an illumination level in the working area of 500 lx. This
approach pays consideration to the visual, emotional and biological
eects or articial light and requires that the vertical illumination in
work premises should exceed 250 lx.
In order to achieve good visual comfort within an area the aver-
age luminance on the room’s walls, as a general rule, should not
fall below 30 cd/m². It is normal practice to translate luminance
conditions to relative illuminance, as illuminances are used as guide
values in light planning. Nevertheless, in this context it should be
pointed out that today’s computerised calculation programs allow
the calculation and documentation of dierent luminances for
room surfaces. The table below provides information about recom-
mended relative illuminances between the workspace and room
surfaces for a typical area.
Luminance conditions with indirect lighting
With indirect lighting the average luminance on the ceiling
should not exceed 500 cd/m²,
with a maximum acceptable
luminance of 1500 cd/m². The luminance transition should vary
gradually across the surface being lit to avoid the lighting from be-
ing distracting and uneven. The luminance balance (L
min
/L
ave
) should
not exceed 1:10.
For the background lighting on the walls the maximum lumi-
nance should be limited to 1000 cd/m².
L
max
< 1500 cd/m²
L
ave
< 500 cd/m²
L
max
< 1000 cd/m²
Luminance limitation for luminaires that can be reflected in the
monitor
Limitations of luminaire luminance at
workplaces with monitors classified in ac-
cordance within ISO 9241-7
Luminaire’s maximum average lumi-
nance cd/m² (applies to luminaires that
can be reflected on the monitor)
Negative monitor
polarity
(dark background)
Positive monitor
polarity
(light background)
Monitor class I and II – direct lighting
Good, average or normal reection treatment
≤ 1000 cd/m² ≤ 1500 cd/m²
Monitor class III – direct lighting
Inferior screen quality without reection
treatment
≤ 200 cd/m² ≤ 500 cd/m²
Monitor class III – dir./indir. (≥10 % uplight)
Inferior screen quality without reection
treatment
≤ 500 cd/m² –
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