Discomfort glare from windows

An awkward and unpleasant 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 even discomfort in the form of increased heat radiation can also occur. Thus sun screening in some form is necessary in most buildings.

Screening can be achieved through the design of the building, external sun screens, low transmitting glass (sun glass windows) or through Venetian blinds or curtains. Glare can also occur from a diffuse sky viewed through a window. This form of glare can usually be reduced by choosing lighter colours for the walls near the window or by increasing the luminosity of the walls with separate lighting.

Examples of discomfort glare from a window:

  • Reflective glare.
  • Reflections on visual objects or their surroundings can completely impair sight.

Even if glare does not occur from a luminaire or other highly reflective surfaces, it can occur in the form of reflection. Polished and reflective materials should not be placed in areas where glare can arise, especially in work areas. If polished surfaces cannot be avoided lighter surfaces are more preferable than darker surfaces.

An example is a computer monitor screen surface where reflections are usually perceived as more disturbing on monitors with dark backgrounds and light text, than on monitors with light backgrounds and dark text.

Reflections from reflective materials or reflective glare can usually be prevented with the following actions:

  • Suitable luminaire positioning.
  • Selecting luminaires with low luminous intensity and effective screening.
  • Selecting matt materials for reflective surfaces.
  • Selecting luminaires with a larger surface area.
  • Select light colours for ceilings and walls.