In uk.sci.astronomy message , Sat, 16
Feb 2008 10:01:23, Abo posted:

Apparently they are mulling over the idea of switching off the town's
street lights in an attempt to cut back on their electricity usage.

The most modern street lights, I gather, nowadays use multiple LEDs,
which are cheaper to run.

Apart from that, multiple LEDs could give three other advantages, which
I've not seen mentioned though they ought to have been realised : (1) An
appropriately-fitted luminaire could be turned on/off LED-by-LED (or by
PWM), which is nicer for the electricity supply and avoids sudden
changes in illumination; (2) A small proportion of the LEDs could be
left on all night, to provide a modicum of illumination; (3) Any
transition between lit and unlit areas could be tapered.

For astronomers, there can at least be the hope that the size and low
dissipation of LEDs may permit the production of luminaires that are
more directional.

--
(c) John Stockton, nr London UK.
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