Friday, March 17, 2017

Spotlight on air

My colleague Martin Morgan-Taylor sent me this photo of a newly installed floodlight that doesn't actually seem to be pointed at a building facade, or really anything in particular at all.

Misdirected floodlamp by Martin Morgan-Taylor is licensed
under a Creative Commons Attribution 4.0 International License.

There are some flower beds nearby, but if they are meant to illuminate the flowers they are pointed in the wrong direction! (Incidentally, surely only someone who hates fireflies, glowworms, and other nocturnal insects would do such a thing, no?)

The design is such that the lamps will produce a lot of glare, making vision in the area worse. At the same time, about half of the light emitted is going to go up into the sky, producing skyglow.

One final, but really important point: It does not matter how "efficient" this lamp is in lumens/Watt. Almost none of the light produced by this lamp will assist humans with a visual task, so the true efficiency in the commonsense meaning of the word is near zero.

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