Discomfort glare from windows
Discomfort glare arises when a person looks out of a window in the direction of the sun or when direct sunlight falls against surfaces within the normal field of vision. In these situations, there is also discomfort in the form of increased heat radiation. Sun screening in some form is thus necessary in most buildings.
Screening is normally achieved through the design of the building, or through external sunscreens, low-transmission glass, also known as sunlight windows, or through venetian blinds or curtains.
Glare can also occur from a diffuse sky viewed through a window. This glare can ordinarily be reduced by choosing light window walls or by increasing the luminosity of the window wall through separate lighting.
Examples of discomfort glare from a window:
- Reflective glare.
- Reflections on the vision object or its surrounding areas are often completely vision impairing.
Even if glare does not occur from a luminaire or other polished surface, it can occur in the form of reflection. Polished and reflective materials should therefore be avoided where glare can arise, especially in work areas.
If polished surfaces are necessary lighter surfaces are more preferable than darker surfaces. An example is the surface on a computer display where reflections are usually perceived as more disturbing on negative displays with dark backgrounds and light text than on positive displays with light backgrounds and dark text.
Reflections from reflective materials or reflective glare can usually be prevented by the following actions:
- Suitable luminaire placement.
- Choice of the low luminance luminaires with effective screening.
- Choice of matt surface coverings.
- Choice of large-surface luminaires.
- Choice of a light ceiling and walls.