Office with Computer workstations present complex visual needs. Computer operators have different light requirements from workers who read hard copy documents. Glare and monitor screen reflections can produce visual discomfort. Individual differences affect light requirements. A 60 year-old worker requires up to 10 times more light than a 20 year-old worker. Providing optimal illumination levels for multi-worker offices is difficult.

Contrast, brightness, quantity of light, and color of light affect the quality of lighting. Contrast between a visual target and the background must be sufficient for the worker to clearly view the task. A ratio of 1:3:10 is best. The task area should be up to 3 times brighter than the immediate surrounding and 10 times brighter than the peripheral area. Conversely, excessive contrast levels strain the eye and should be avoided.

The color of light affects visual comfort and productivity. Several types of lighting are available. Full spectrum fluorescent lights are designed to mimic natural light but cost more than standard bulbs. Due to cost, most offices use standard fluorescent bulbs. Bright white bulbs offer high illumination levels but can increase glare cause eye discomfort or headaches. Soft white fluorescent bulbs are warmer in color, create less glare, and are often a better choice. Whenever possible, offices should be designed using indirect lighting fixtures to eliminate glare and direct light as desired.

Recommended light levels for today’s computerized office is 40-50 foot-candles. Intensive work such as data entry can requires higher lighting levels of 50-70 foot-candles. This can be provided by task lighting systems. Illumination on the document should be relatively high, while lighting on the screen should be kept relatively low. Lighting should come from two directions on either side of the worker to reduce shadows and improve lighting consistency. If task lighting is not provided, the Human Factors Society recommends overall lighting levels of between 20-50 foot-candles for computer operators. Light levels should never exceed 75 foot-candles if there is uniform lighting in the room.

Reflections and glare can interfere with visual comfort when working at a computer. Glare sources can include lights, windows, shiny surfaces, glasses, and white clothing.

Glare and reflections can be reduced in the following ways:

• Reduce light from windows. Consider full or part coverage of windows with the use of curtains, louvers, awnings, canopies and neutral-density film coverings.
• Reduce ceiling glare.
  • Use ceiling fixtures that provide controlled, indirect lighting. Indirect lighting fixtures are preferred over grates and parabolic louvers that can create uneven lighting with shadows.
    o Purchase low-glare bulbs or cover bright bulbs with prismatic lenses, polarizers and filters.
  • Remove bulbs, install adjustable level light switches, or turn off switches. (This will reduce but not necessarily eliminate glare.)
• Use indirect lighting sources and task lights. Position task lights to avoid shadows. Aim the light at specific targets (source documents).
• Reduce other brightness sources. Avoid wearing white shirts. Do not use glossy, reflective paints on walls or select highly reflective work surfaces.
• Use barriers. Use partitions to block lights from windows and other bright sources.
• Tilt the screen. Tilt the monitor screen to avoid reflections. Positive tilts often reflect ceiling fixtures.
• Use a visor. A visor placed over the screen or on the users head will reduce glare from overhead lighting sources.
• Change workstation orientation.
  • Sit at right angles to windows and at least 3 feet away from the window.
  • Avoid positioning worker directly in front of or in back of overhead lights. (The operator should not have a light source or fixture within direct visual field when looking at the monitor screen.)
• Consider screen treatments. A good quality anti-glare screen can be very effective in reducing visual discomfort and reducing awkward neck, shoulder and back postures used to avoid the glare.
• Change screen/character background. Character and screen color can be changed with most word processing programs. Black characters on a white screen (a negative contrast) will produce less glare than white characters on a blue background (a positive contrast). However, flicker sensitivity may be increased due to the larger luminous surface.