One factor in lamp selection is the dirtiness of the environment. But what about the accumulation of dirt in a fairly clean environment, such as an office?
A poor choice of lighting fixture could mean lighting that everyone complains about, after only a year or two. A gym with high-bay HIDs had increasingly poor light due to dirt buildup, but the fixtures were inaccessible for cleaning by staff. Eventually, the replaced those fixtures with less dust-intensive ones (but didn’t hire the original contractor for that, or any other, work).
With today’s high-efficiency fluorescent lamps, office relampings may be several years apart. In the meantime, light degrades to unacceptable levels. Or does it? That depends on the fixture you specify.
Fixture selection makes a huge difference in the light versus dust battle. But it’s not as simple as just picking the most dust-reducing fixture. You must weigh several factors against each other, as a fixture designed to keep out dust may do that at the cost of maintainability, heat dissipation, or light output.
Cost and availability are also factors, so simply going with a premium fixture that ranks well on all these factors might not be possible. In some cases, it is the best choice. If, for example, the space being lit is a leased office that carries a high revenue per square foot, you can (and should) justify spending a little more to get a fixture that ranks high on light output and also helps prevent dust build-up.
Source: Mark Lamendola | Mindconnection