The correct classification of workplace by a type of operations performed plays an important role in the development of designs of energy-saving lighting systems, since the illuminance values
, which the lighting system is to be dimensioned to, are based just on these documents .
For instance, all Handbook recommended lighting standards, which get adopted into the energy codes, mandate quantitative illuminance values
and concomitant LPDs, but no qualitative values for user benefits.
As for energy consumption in existing lighting environments, the average illuminance values
in 17 domestic residential spaces were measured and presented in Figure 1.
Since walls are located in the main field of vision and illuminated walls contribute to a subjective sense of brightness, this type of lighting has particularly high relevance for perception-oriented and efficient illumination of rooms, although lighting guidelines are often limited to specifying horizontal illuminance values
[Cuttle, 2010; Krautter and Schielke, 2009; Loe and Rowlands, 1996].
A limitation of the daylight autonomy index is that it excludes illuminance values
slightly below the threshold and that it does not consider the problem of glare due to excessive daylight.
The results are shown in Table 5, indicating relative illuminance values
but not against benchmarks.
Contour lines are drawn through illuminance values
. Each contour, from the center out, represents approximately 50% of the value of the previous contour.
Similarly, in lighting, illuminance values
for interiors are often given with decimals.
were collected for 300 days, every 10 minutes, including daytime.
The lighting electricity demand then can be determined from the illuminance values
for each time step.
Figure 3 shows typical ranges of vertical illuminance values
that can be expected for a variety of interior and exterior conditions.
The predicted stray light illuminance values
measured for each shield and luminaire orientation are shown in Table 1.