One wants to minimize the light loss within the fixture itself as well, so as to maximize the use of the light output. We strongly recommend full cutoff fixtures. This means that there will be very little spill light, up light, or light trespass. Any building facade lighting, landscape lighting, or other such lighting should use as low a wattage lamp as possible, and the beams should be tightly controlled, to minimize waste light. Lighting source .
Lamps differ greatly in the amount of light output produced for the amount of wattage they use.
IDA Information Sheet No. 4 gives specifics, but we can say here that low pressure sodium sources are the most efficient, followed by high pressure sodium, then metal halide. Neither LPS nor HPS give good color rendering, LPS giving none at all. Many applications of nighttime lighting, however, do not require color rendering, and LPS is an excellent choice for such applications. Lighting suppliers . There are many sources of lighting fixtures.