It's funny that so many (sales?)people online talk about LED street lights as if they're the best thing since sliced bread, and incessantly (falsely) claim that they're vastly more efficient...
Low pressure sodium (LPS) lamps and LED lamps are *comparable* in efficiency.
The key difference is that the monochromatic amber light created by LPS street lights doesn't disrupt the circadian rhythms of humans or wildlife nearly as much, & doesn't interfere with astronomy as it's easy to filter out.
@IrelandTorin did not know this.
@AnnetteTRemain @IrelandTorin efficiency normally needs to be judged in context. LEDs have less "wasted" light because they can be directed much more precisely, have longer term energy savings via better control systems, and reduced maintenance costs. For very large installations, the long term cost savings can be significant (smaller lamps, less frequent maint., 2x - 4x lifecycle). LPS's also have hazardous waste that requires proper disposal.
But the disruption you mentioned has a cost too.
@IrelandTorin I use outdoor leds. I would like something better for nature but have to go with security. @hallmarc
@hallmarc @AnnetteTRemain Note I'm specifically contrasting LEDs with LPS.
I won't argue that LEDs blow metal halide (MH) & mercury vapour (MV) out of the water. If those were the other options, there'd be no contest.
I must note that LPS lamps do not contain mercury, unlike most of their HPS cousins, so there's less of a concern re: hazardous waste with LPS.
The main headache with LPS is its 0 CRI... but with appropriate signage / line paint design, I'd argue that's fine for street lighting.
@hallmarc @AnnetteTRemain Well-thought-out reflector systems with good-quality mirrors can adequately solve the directionality problem.
The touted lifespan benefits of LEDs have, in many cases, not materialized due to a combination of manufacturing defects, design flaws, good 'ol-fashioned corner-cutting, deliberate planned obsolescence... etc.
Semiconductor manufacturing for LEDs also produces vast amounts of hazardous waste. You wouldn't believe some of the nightmare chemicals they use!