Retro-fitting streetlights in town to be dark sky night compliant

sw_ross

Senior Member
The small town that we're in has historic looking lamp posts on most corners in town and space out about every 200' on the perimeter streets that have a high pressure sodium fixture mounted on top of a metal post that's probably about 12-14' off the ground.

Last year the town adopted a dark sky night initiative. Up to this point they haven't done anything regarding changing/retrofitting the fixture at the top of the post.

The way it appears to be set up is that a set number of lamps are controlled by photo-eyes with contactors located throughout the town. A number of the fixtures do not work, whether it's a problem with the control circuit/device, or a interrupted power supply to the fixture hasn't been diagnosed yet.

We're thinking the whole scenario is prime for a proposal to the city to upgrade their lighting to be darky sky compliant and fix a lot of their current issues.

Problem is I don't know a ton about being dark sky night compliant other than a little bit of info on the web. Also trying to learn what I can about retrofitting the current posts with a compliant fixture and tracking down a supplier.

If anyone has experience with this situation I'd be grateful for any advice.

Thanks,
Sky
 

Fulthrotl

~~Please excuse the mess. Sig under construction~~
The small town that we're in has historic looking lamp posts on most corners in town and space out about every 200' on the perimeter streets that have a high pressure sodium fixture mounted on top of a metal post that's probably about 12-14' off the ground.

Last year the town adopted a dark sky night initiative. Up to this point they haven't done anything regarding changing/retrofitting the fixture at the top of the post.

The way it appears to be set up is that a set number of lamps are controlled by photo-eyes with contactors located throughout the town. A number of the fixtures do not work, whether it's a problem with the control circuit/device, or a interrupted power supply to the fixture hasn't been diagnosed yet.

We're thinking the whole scenario is prime for a proposal to the city to upgrade their lighting to be darky sky compliant and fix a lot of their current issues.

Problem is I don't know a ton about being dark sky night compliant other than a little bit of info on the web. Also trying to learn what I can about retrofitting the current posts with a compliant fixture and tracking down a supplier.

If anyone has experience with this situation I'd be grateful for any advice.

Thanks,
Sky
light pollution is a big deal with LEED certification, but the problem is going to be selecting
a cute, historically correct light fixture that the customer will like, that doesn't scatter light
everywhere.

most every new light fixture made is dark sky compliant, but most of them look like they
came right out of DWELL magazine. historical, they aren't.
 

GoldDigger

Moderator
Staff member
light pollution is a big deal with LEED certification, but the problem is going to be selecting
a cute, historically correct light fixture that the customer will like, that doesn't scatter light
everywhere.

most every new light fixture made is dark sky compliant, but most of them look like they
came right out of DWELL magazine. historical, they aren't.
If your existing fixtures are the "globe on top" type you may be able to get replacement globes that cut off upward light.
 

gadfly56

Senior Member
If your existing fixtures are the "globe on top" type you may be able to get replacement globes that cut off upward light.
I always thought that there was as much an issue with reflected light as sky-ward directed light. If you have a lot of light surfaces (keep the heat down in Arizona, say) then you could have a fair amount of reflection adding to the problem. I'd think you need to redesign coverage patterns to keep this to a minimum. And maybe there's no good solution; people want to see where they are going on the white sidewalk late at night.
 

GoldDigger

Moderator
Staff member
I always thought that there was as much an issue with reflected light as sky-ward directed light. If you have a lot of light surfaces (keep the heat down in Arizona, say) then you could have a fair amount of reflection adding to the problem. I'd think you need to redesign coverage patterns to keep this to a minimum. And maybe there's no good solution; people want to see where they are going on the white sidewalk late at night.
A large part of the solution is keeping the overall light level to the minimum amount required, which benefits from proper distribution instead of having hot spots to keep the cold spots from being too dark.
It also benefits from control (selection) of the light spectrum produced.
 

tom baker

First Chief Moderator
Staff member
Manufacturers will state their luminaires are dark sky compliant. There is a BUG rating that came from IESNA and Dark Sky - bug is backlight, uplight, glare. the term cutoff is no longer used.
You can retro luminaires with LED lamps or install new heads. Get in contact with some reps from Hubble, GE, or Cooper, they will be glad to help and do some show and tells. Also check with your utility to see if they have any lighting resources, most do
 

Rampage_Rick

Senior Member
The biggest change around here is nobody is using drop-glass cobraheads any more. As units require maintenance they're being swapped to flat-glass units.

p9210921.jpgp9210922.jpg

I guess the simplest question is whether the existing fixtures leak any light above horizontal?
 

mbrooke

Senior Member
Skipping ahead I'd personally use low pressure sodium. Nearly as efficient as LED and observatory friendly.
 

GoldDigger

Moderator
Staff member
Ok, dumb question. :ashamed1::dunce: Why?
Simple geometry. If the glass extends down from the outer edge of the lamp then light refracted or scattered off the glass can be seen from an angle above the horizon, so it contributes to direct light pollution as well as indirect light pollution.
Flat glass also allows you to control the beam geometry more precisely by the reflector contour alone.
 

peter d

Senior Member
Skipping ahead I'd personally use low pressure sodium. Nearly as efficient as LED and observatory friendly.
LPS? :sick: There's a reason it never caught on and that's because it's genuinely awful. Lamps are expensive, hard to find and the CRI is 0.
 

mbrooke

Senior Member
LPS? :sick: There's a reason it never caught on and that's because it's genuinely awful. Lamps are expensive, hard to find and the CRI is 0.
And the life is only 15,000 hours, less than HPS of 24,000 and 40,000 on newer long life none cycling models. :thumbsup: Heck you can now get dual arc tube lamps that bing in at 80,000 hours:


https://www.sylvania.com/en-us/newsroom/press-releases/Pages/OSRAM-SYLVANIA-Introduces-80,000-Hour-LUMALUX-PLUS-XL-ECOLOGIC-Lamps.aspx

But in all seriousness they are the most energy efficient light source next to LED. They are about 80 to 90% efficient while HPS is only 50%, MH about 40%. No ignitor either on North American ballasts, low watt versions can use a reactor ballast on 480 volts (even more efficient), near instant restrike, no mercury, and better cutting through fog. Ive driven through Mass Pike before they started replacing them and the light is indeed better during adverse whether IMHO. You can still order LPS lamps through major lighting distributors. Further the yellow single spectrum light is gentler on the bodies natural sleep cycle. Lights rich in blue colors can mimic daylight.


The only reason LPS lamps did not catch on was that they were applied like HPS lamps in every way. This resulted in long(er) fixtures to support the max wattage of 180 watts, photo-metrics/light distribution was never considered, wind load under minded on mast arms, and because a 180 watt LPS is still dimmer to a 400 wat HPS it resulted in under illumination when applied to high ways. As a result LPS became a failure but only because of a failed understanding in correctly applying a new, different technology. LPS has had tremendous success in the UK, Europe, New Zealand and many other parts only to be recently replaced by LED, but not without a problem:


http://www.flagstaffdarkskies.org/for-wonks/lamp-spectrum-light-pollution/




The advantage of sodium for observatories is that the light is mostly in one very narrow band that is easily filtered.

Yup, monochromatic. They are mandated in parts of California.
 

iwire

Moderator
Staff member
The only reason LPS lamps did not catch on was that they were applied like HPS lamps in every way. This resulted in long(er) fixtures to support the max wattage of 180 watts, photo-metrics/light distribution was never considered, wind load under minded on mast arms, and because a 180 watt LPS is still dimmer to a 400 wat HPS it resulted in under illumination when applied to high ways. As a result LPS became a failure but only because of a failed understanding in correctly applying a new, different technology. LPS has had tremendous success in the UK, Europe, New Zealand and many other parts only to be recently replaced by LED, but not without a problem:
:lol::happyno:


They did not 'catch on' because they are disgusting.

The only place you could get away with them is industrial.
 
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