[CFDS] good LPS use should be revived

[Jan Hollan <jhollan@amper....muni.cz>]

> The fact remains, LPS is becoming less common and one cannot turn back the
> clock.

Chris,

we should persistently try, not back, but forward. LPS light is the least
damaging the wildlife and health (at least 10 times less disrupting
circadian rhythm than MH), and it's the most Kyoto-compliant one.

> What is more, LPS is basically uncontrolled and cann't be well directed due
> to the tubular nature of the source.

At least from linear ones (unlike U-shaped ones), the light can be
directed quite well. Of course, the luminaires have to be broad enough, if
the uniformity should be good even for distances among luminaires being
five times their height.

Along the tube, a grid can be used as for the interior linear fluorescent
lamps, giving no possibility to have maxima at 65 degrees from nadir, but
avoiding well too much spread outside the road. Centrally mounted over the
street (like most linear fluorescents in Vienna), they could work very
well.

Making a more expensive luminaire, with excellent geometry, is a good
investment.

I agree that old LPS are often a nightmare. However, the problem is not in
the source, but in the bad fixtures. Some not so bad fixtures flat-glass
fixtures exist, much better can be done.

I admit that light spectrum is only secondary to full shielding, or
tertiary, after the light amounts. We are of course sure that full
shielding is to become mandatory. But a lamp spectrum should not be
neglected.

As said many times, LPS can be easily combined (even in a single
luminaire) with fluorescent, to get colour vision at the evening. Late at
night, colour distinction becomes so much less important, that fluorescent
can be switched out. (In Vienna, they switch off each second at night; if
the remaining would be LPS, it would be an ideal combination.)

The present drive toward just white light outdoors (it's behind the MLO as
well) is a wrong one. White is bad for night. And bad for the climate.
Yellow is the right, decent choice.

jenik



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