Reducing Light Levels

Whenever you provide more light than necessary to do the job, you're spending too much for energy. Reducing light levels is a fast, easy and inexpensive way to save energy and money. You can reduce your light levels in such a way that you don't sacrifice lighting quality - in fact you may even improve lighting quality.

Task Lighting

Most commercial facilities are designed with an area lighting system, which provides uniform illumination. Task lighting is a design approach that provides more light where it is needed and less light where it is not. With task lighting, each workstation is illuminated at the required level for the tasks performed there. More difficult visual tasks, such as drafting, are provided a higher light level. Task lighting also allows higher levels for employees with vision problems or special needs. The ideal approach combines low-level area lighting with task lighting wherever possible.


The simplest way to reduce light levels is to delamp or remove unnecessary lamps. For incandescents, simply remove the lamps and cover or protect the socket so that it is not a safety hazard. For fluorescents, remove the lamps and disconnect the associated ballast. In most cases one ballast is connected to two lamps. If only one lamp is removed the remaining lamp will not operate although, the ballast will continue to draw up to 15 watts when energized.

Delamping can cause some problems. For example, if you remove one pair from a four-lamp fixture, you may create shadowy areas that interfere with work. Reflector installations can reduce the shadowy distribution and increase the light output of the remaining lamps. If you want to reduce the light level of a four-lamp fixture by 25%, you may not be able to remove one lamp without preventing the companion lamp from working.

Light Reduction Devices

Several products are available to replace standard fluorescent lamps allowing companion lamps to operate. In many cases, they result in better, more uniform lighting by eliminating shadowy areas delamping can produce.

A dummy tube is a glass tube the same size and shape as a fluorescent tube that maintains the ballast's connection but provides no light. It lowers the overall light output of a two-lamp fixture by 50%. A phantom tube is similar to a dummy, but lowers overall energy usage and light output by 66%. "Thriftmate 33" and "Thriftmate 50" lamps match with standard F40- fluorescent lamps. They reduce the overall energy use and light output by 33% and 50%, respectively. For instance, if you want to reduce the light level of a four-lamp fixture by 25%, you can either replace one F40 lamp with a dummy or use a " Thriftmate 50" with an F40 lamp.