Specular reflectors great savers
Specular reflectors great savers
The efficiency of existing fluorescent light fixtures can be improved by specular retrofit reflectors. These mirror-like devices can be mounted inside existing fixtures to direct light out of the fixture more efficiently. A well-designed specular reflector can typically boost fixture efficiency by 20 to 30%, depending on the fixture geometry, the optics of the reflector, and the state of the fixture before installation of the reflector.
According to a recent EPRI fact-sheet, retrofit reflectors are most commonly used in conjunction with selective delamping. By removing two lamps from a four-lamp fixture and installing a specular reflector, energy use can be reduced by 50% while light output decreases by 25 to 40%. This reduction in light output may be suitable in spaces that are currently overlit based on today's recommended light levels. In other cases, the reflector installation can be supplemented with higher output lamps, electronic ballasts, and/or improved lenses to recover much of the reduction in light output.
One example of how fixture efficiency can be improved by using retrofit specular reflectors can be found at the corporate headquarters of Pirelli Armstrong Tire Corporation. The fact sheet describes how Pirelli upgraded 4000 1x4 two-lamp F40 fixtures to one-lamp T-8 fixtures.
Before: Two 34 W T-12 lamps and one magnetic ballast/fixture. (83-watts/fixture).
After: Custom silver-film specular reflectors, one 32W T-lamp centered in each fixture, and one electronic ballast per two fixtures. (29 watts/fixture). The result is a 65% energy savings with no change in maintained light level. With annual savings of US$ 58 000 (not including air-conditioning savings), an installed cost of US$ 181 280, and a United Illumination rebate of US$ 53 118, the investment pays for itself in 2.2 years.
Replacing a very dirty fixture plus reflector will, of course, result in a relatively small change in light levels.
(Source: High-Efficiency Electric Technology Fact Sheet, Specular Retrofit Reflectors, EPRI)
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