Ergonomic Lighting

Ceiling suspended, indirect lighting.
Control outside light with blinds and shades.

Good office lighting provides adequate light levels for all tasks performed in the office. It should reduce or eliminate glare and reflections. In an office of any size, the best solution to glare and reflections on the screen is ceiling suspended, indirect lighting. This is sometimes referred to as "uplighting." The underside of the lamps should be the same color as the ceiling. Wall mounted sconces may also be appropriate in certain instances.

Understanding a little bit about the principles of lighting can help improve any office environment. First we have to understand what we are trying to accomplish. When evaluating a monitor, high contrast is desirable. You want the letters to stand out from the background.

When evaluating what is reflected from the screen, it is the opposite: contrast is the enemy. Contrast reflected onto the screen competes for the user's attention with the contrast on the screen. In some cases this can be an irritation, but in others it can make sections of the screen difficult to read.

Aside from absolute brightness, the main problem with direct ceiling lights is that they provide a high contrast with the rest of the ceiling. Many guidelines mistakenly specify a luminance (brightness) value for ceilings and walls. While absolute intensity is important (a bright light reflecting off the screen will always cause problems), the contrast is much more critical. Interrupting the ceiling with patches of bright light almost guarantees competing reflections on the screen.

What can you do if you have computers, but still can't install indirect lighting?

With small office areas, it may be possible to reposition desks, or remove or shade individual glare sources. However, this can become unwieldy for large areas. Repositioning a lamp may just transfer the problem to another workstation.

In many instances it is possible to retrofit deep cell small cube parabolic or paracube lenses to replace other types of lenses. If the cutoff angle (the angle beyond which the bulb cannot be seen) is acceptable, reflections of the light source from the screen will be eliminated. In other instances it may be possible to install shields or screens to reduce or eliminate the reflected contrast.

Reorienting the screen can help in some instances. But, as we saw earlier, it should not be tipped down. Hoods can be effective, as can removing bulbs. Task lights can supplement lower levels of ambient light. Remember, since the front of the VDT screen is glass, something is going to be reflected from it. The goal is to reduce the contrast in those reflections.

New monitors should have anti-reflective screen coatings. You can also apply these coatings to older monitors. Rea (1991) offers an excellent discussion of VDT lighting.