How to Achieve Optimum Light Levels

October 13, 2014 By Karen Henry

light-meter-energy-manageToo much or not enough light in a building can cause occupants to suffer from headaches and eyestrain. Before investing in expensive retrofits, an article in Buildings recommends that building owners and facility managers measure their light levels to determine if the problem might be simpler, and less expensive, to solve.

A light meter is a relatively inexpensive tool that can be used to measure a room’s illumination level. Measurements can be taken on a horizontal plane (the top of a desk) or a vertical plane (the wall). All areas in the building should be measured with the same light meter, and the meter should be recalibrated once a year.

There are plenty of smartphone apps that claim to measure light level, but because such applications are dependent upon the quality of the camera in the smartphone, the readings can be inconsistent and unreliable, the article cautions.

Some companies have corporate specifications that dictate workplace light levels and lighting power density. For those that don’t, local building codes and guidelines from the Illuminating Engineering Society (IES) can be helpful. IES guidelines provide a minimum and a maximum illumination level, the minimum being the illumination for someone with exceptional eyesight, and the maximum being for someone who requires more light to see or to complete a difficult task. A building may use different illumination levels based on the area and what it is used for, but the illumination level should never go below the minimum IES guideline.

Taking temperature measurements may help to determine if the wrong fixture is being used in a certain area. Heat-sensitive fixtures, for example, may get damaged in environments that are too warm.

After measured light levels are compared to corporate specifications or IES recommendations, lamps and ballasts should be examined. The wattage that is being pushed out of a bulb is dependent on the lamp and the ballast that it’s using. The ballast should have specifications that describe how much energy it draws.

There are also a number of strategies facility managers can use to help manage lighting costs.

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