26 replies to this topic

[earlyriser]

I thought it might be useful to have a list of cites installing LED lights, and what Correlated Color Temperature they are going with. This might be useful when speaking to city and town councils. If you know of a city that has announced a choice, add it here.

 

Chicago: 3000K

https://energynews.u...nd-controversy/

 

Davis California: 2700K

https://www.davisvan...h-2700k-lights/

 

Denver: 3000K 

https://www.denverpo...led-blue-light/

Edited by earlyriser, 27 March 2019 - 05:51 AM.

[SarverSkyGuy]

Pittsburgh lights will be changed to LEDs starting in 2019. The streetlights will be shielded, dimmable and 2700K or below.

[csrlice12]

Sorry, on the local news this morning, Denver is now using 44K LEDs....worst of the worst.

[earlyriser]

Sorry, on the local news this morning, Denver is now using 44K LEDs....worst of the worst.

I think that is the number of lights they are replacing, not the correlated color temperature.

[spacemunkee]

Sorry, on the local news this morning, Denver is now using 44K LEDs....worst of the worst.

Well on the K scale from 1000-10000, 44k would be just fine. VERY dim and yellow. Won't hardly put off any light at all!  

 

Unless you are meaning 4400k... then eewwww...

[sg6]

The big problem will come if any of the LEDs emit at the OIII or Hb wavelength.

Then imaging with narrow band has problems.

 

There are a few varieties here and oddly the "cool" ones are by far the most pleasant. Some of the small white ones are reasonable, it is the high level large flat white ones that are the worst.

[AntarcticDave]

Here is an article on the Denver LED initiative - 3000k color temperature:  https://www.denverpo...led-blue-light/

[Greyhaven]

Just attempting to determine what LED street lights the town installed here Lewiston Maine. The contract was for 3 different units   Type 1   40watt  4700 lumens   Type 2  60watt 7100 lumens  and Type3 115watt 14700 lumens  How, if they do, lumens and temperature color relate? I'm thinking some of these lights my be for athletic fields and multi lane bridges,But knowing this town they could be just to ward off evil spirits.

Grey

[spacemunkee]

Just attempting to determine what LED street lights the town installed here Lewiston Maine. The contract was for 3 different units Type 1 40watt 4700 lumens Type 2 60watt 7100 lumens and Type3 115watt 14700 lumens How, if they do, lumens and temperature color relate? I'm thinking some of these lights my be for athletic fields and multi lane bridges,But knowing this town they could be just to ward off evil spirits.
Grey

You made me curious, and I do electric, but never gave much thought to it.

Of course the wattage is just what it uses, more wattage, more lumens(brighter).
But the K scale comes down to the metal used in the LED.

Quick thing about it.

https://www.lrc.rpi....s/led/color.asp

[earlyriser]

Santa Fe is installing 3,000K in residential and 4,000K on main streets.

 

Also mentioned in article:

 

"Large cities such as Chicago and Los Angeles have installed streetlights that are 3,000 kelvins or lower at intersections and residential areas, he said."

Edited by earlyriser, 18 February 2021 - 12:51 PM.

[GeorgeLiv]

For larger cities with numerous suburbs, especially with independent municipalities, color temps for installed LED systems are currently widely mixed.

 

The earliest color temps installed circa 2010 were either 6500° or 6000°K. These were implemented with mesopic-factoring. Many of these installations were so dim and the LED heads so poorly made that most of these have gone through further upgrades to warmer toned systems. The American Medical Association (AMA) report also came out in June of 2016, warning of the potential harm to people with the high blue light content in LED night-time lighting. In some regions converted to disproportionately blue 6500°K induction or LED systems, some residents complained that the lighting was either too harsh or discomforting. Due to such complaints and the AMA report, retrofit programs under contract started specifying a lower color temperature for LED.

 

The lighting industry, being virtually unregulated, has moved from dim, ~6000°K LED, to bright neutral toned 4200°K (or 4000°K) LED, to slightly inefficient 2700°K LED, which are actually pretty good for a phosphor-based systems, all in less than a decade.

 

In areas where conversions occurred by 2015, LED systems closer to a 4100°K color temperature were chosen. By 2018, 3000°K and even 2700°K were preferred, one reason being a greater awareness of the importance for foveal (central) vision compared to peripheral vision.

 

Currently established by experts is the notion that yellow light benefits foveal vision, while blue light benefits peripheral vision. Since forward vision seems more crucial in driving tasks, the latest consideration for street-lighting favors warm toned LEDs to be installed for adequate foveal vision.

 

By 2018, installed LED systems were unlikely to be near 6000°K, less likely to be at 4000°K, but a great deal likely to be closer to a 3000°K color temperature. In comparison, HPS lighting is near the 2100°K color scale and LPS/SOX are in the 1800°K range.

 

Because of these trends, many cities have ended up with a mix of CCTs. Example: color LED temperatures for both Brooklyn and Queens were at 4000°K which were completed by the end of 2016. Because of complaints about the new LED color in these boroughs and the general awareness of that 2016 AMA report, the contractor for The Bronx, Staten Island and Manhattan (all of which had the same contractor) was required to install luminaires in 3000°K starting in January of 2017.

 

Unfortunately, this is not necessarily true for commercial or industrial properties where highest profits can still be obtained by lighting companies when installing neutral and cool-toned LED systems. Photographed three years apart using exactly the same camera settings and equipment (as per EXIF data), the newly installed LED wall-packs appear a bit brighter than the soiled and under-serviced HPS wall-packs at the top. The change in color is quite contrasting, rising from about 2100°K to 5000°K. This is what's happening for the majority of private commercial and industrial property retrofits..(The wattages are known from the discarded LED packages which contained broken up parts of the old HPS lamps and fixtures)..

 

 

 

 

[GeorgeLiv]

Just attempting to determine what LED street lights the town installed here Lewiston Maine. The contract was for 3 different units   Type 1   40watt  4700 lumens   Type 2  60watt 7100 lumens  and Type3 115watt 14700 lumens  How, if they do, lumens and temperature color relate? I'm thinking some of these lights my be for athletic fields and multi lane bridges,But knowing this town they could be just to ward off evil spirits.

Grey

Lumes is a measure of luminous flux (amount). The Watts is closely tied to the luminous flux.

 

Correlated Color Temperature or C.C.T. has nothing to do with watts or lumens. Measured in degrees Kelvin (°K) it's a temperature rating to indicate the hue or tone of the light. In phosphor-based LED systems, the choice of ingredients results in the differences in hues. It turns out that the highest efficacies are obtained from cool-toned LED while the lowest with warm toned LED systems.

[earlyriser]

It appears Knoxville TN is deploying 3000K streetlights.  

 

https://www.knoxvill...nversion_f_a_qs

[kevin6876]

It appears Knoxville TN is deploying 3000K streetlights.  

 

https://www.knoxvill...nversion_f_a_qs

Good FAQ on Knoxville's site!  Thanks for sharing that.

 

Smithfield RI - 3000K

[earlyriser]

Phoenix is 2700K.

 

https://www.phoenix....ght-program-q-a

 

"The city's standard kelvin for LED streets lights is 2,700 kelvins. In 2016, the Council revised the city's standard kelvin level for street lights from 4,000 kelvin to 2,700 kelvin. The revision was based on American Medical Association guidelines and extensive community input, potential environmental issues, technical lighting standards, and projected energy savings."

 

The above point might be a good one to make to cities deploying 4000K lights. 

Edited by earlyriser, 05 January 2024 - 02:49 PM.

[earlyriser]

You may be wondering, why the sudden interest in this old thread?  Well, the city of Cincinnati started replacing the HPS streetlights in my area, and they are unfortunately using what looks like 5000K LED streetlights.  So, I'm looking for material to back up an argument that they should be deploying 3000K or below instead.

 

I found the below link to include a lot of useful information on this subject.  And I believe Kansas City did ultimately go with a lower temperature LED streetlight than originally planned as a result of pressure from various groups.

 

https://www.sierracl...-for-better-led

[bedrock]

D.C. primarily has 2700 and 3000K LEDs. In the burbs, well, that's another story.

[GeorgeLiv]

The warning from excessive blue LED starts in the 4th paragraph of this this A.M.A. webpage. The "guidance" pdf they published in 2016 is linked in the first paragraph.

 

 

 

[earlyriser]

Since the 2016 AMA report on the health effects of lighting, there have been additional studies we should also be aware of as they may be cited to rebut arguments in favor of lower CCTs. Below is a link to one study that attempts to measure the effects of streetlight CCT on melatonin levels at typical exposure levels. 

 

https://www.mdpi.com/2624-5175/4/4/49

 

The above study suggests that CCT has a negligible impact on melatonin levels. One significant weakness in this study is that the environmental exposure tests only measured salivary levels on melatonin. As can be seen from the control data presented in figures 1, 3, and 5, the salivary measurements are far less sensitive to changes in melatonin levels than measurements of plasma melatonin. So, I believe this limitation does undermine the study’s conclusions. 

 

There are also significant differences between how each set of test subjects (drivers, pedestrians, light trespass) responded to the control test. The report hypothesizes this could be due to differences in time of day between groups, but it seems to inject some uncertainty into the results. 

 

Author Dr. Ronald Gibbons is involved in a significant amount of research into roadway lights, and appears to be a proponent of 4000K lights as providing better visibility for drivers as compared to 3000K lights. So he is a good search term for locating theses types of studies. 

 

I’ve been looking for studies comparing the visibility provided by 3000K and 4000K streetlights, but have yet to find one that is definitive. 

Edited by earlyriser, 13 January 2024 - 12:28 PM.

[Starlady]

Pittsburgh lights will be changed to LEDs starting in 2019. The streetlights will be shielded, dimmable and 2700K or below.

Not much has happened in the years since this 2019 comment. We got a new mayor. Pittsburgh's 2021 Dark Sky Ordinances implies 3000K or below in the business districts and 2700K or below in the residential neighborhoods. "All lighting shall utilize appropriate color temperature not to exceed 3000 Kelvins with a preference for 2700 Kelvins where possible." If we did that, the sky would get many times brighter. The company making the decision (by next summer) is The Efficiency Network (TEN). Last time I talked to the people in charge of the streetlight design there, they were looking into 2500K. With PA House Bill 1803 in committee calling for 2200K LEDs in streetlights statewide, maybe we'll see a similar drop in what streetlight CCTs we'll get in Pittsburgh. 

[earlyriser]

People in Boulder Colorado prefer lower CCT. Hopefully the city obliges. 

 

https://bouldercolor...ity-cares-about

[GeorgeLiv]

In this new thread I explain how to determine exactly the change that may have occurred for your very own street.

[earlyriser]

Philadelphia is deploying streetlights with a color temperature of 3000K. As I recall, a few years ago Philadelphia was “a 4000K city” according to local officials, so this is a positive development. https://www.inquirer...-pollution.html

[PhillyMoonMan]

Philadelphia is deploying streetlights with a color temperature of 3000K. As I recall, a few years ago Philadelphia was “a 4000K city” according to local officials, so this is a positive development. https://www.inquirer...-pollution.html

I’m actually happy to see that the city reconsidered its 4000K deployment. However, they are using this as an opportunity to increase the level of lighting in almost every situation. I’ve measured up to 130 Lux on South Street with the LEDs.

The good news is, the fixtures will be dimmable, so communities can request changes if they find the lights too bright.

[Matt78]

So, if I am understanding this correctly, the lower, warmer temperatures are better for those of us in the astronomy community? If so, is the benefit for visual as well as photographic?