22 August 2006
light directly in front of the task, producing reflected glare. Unshielded streetlights can
also produce reflected glare on wet pavement, washing out lines on the road. Reflected
glare will limit one's ability to "see" contrast.
2-3.2.1 Like direct glare, indirect glare can be minimized with the type and layout of
lighting equipment. For interior applications, locate direct light to the side or behind a
critical task. Use semi-indirect light to bounce light off of surfaces in order to provide
uniform low glare light with less reflected glare. For exterior lighting, direct the light
away from the observer with the use of low glare, fully shielded luminaires.
Figure 2-4. Semi-indirect lighting minimizes indirect glare.
Overhead glare. Direct luminaires that are immediately over an individual can
cause glare even though the light source is not in the field of view. This type of glare
can produce the same negative effects as direct or reflected glare including eye-strain
2-3.3.1 To minimize overhead glare, use indirect luminaires to light the ceiling surface
and avoid totally direct luminaires. Where direct luminaires are used, make sure that
individuals are not working directly under them.
Requirements to minimize glare:
Follow IESNA recommendations for individual lighting application. Refer
to Chapter 6 and 7 of this UFC or to the Lighting Handbook, Chapter 10
"Quality of the Visual Environment" for specific criteria.
For roadway applications, use fully shielded luminaires. Refer to "exterior
luminaires" in Chapter 5 "Lighting Equipment" and Chapter 7 "Exterior
Considerations to minimize glare:
Indirectly light the ceiling and walls for interior ambient lighting systems.
Refer to specific applications in Chapter 6, "Interior Applications".