A small piece like this will not do justice to the complexity of the lighting plan for Galveston that council members are discussing. Many of us understand from this discussion that light-emitting diode lights, better known as LED, can be 50 percent more energy efficient than the street lights that they replace.

The bulbs are less costly and last for 15 to 20 years instead of two to five. So, LED lighting seems the way to go. But the meaning of the K value of LED lights is central to the discussion and needs some thought.

Clueless as I am in matters electrical, when I first heard about the “4000K” lights being considered, I thought folks meant kilowatts. Not so. The K here refers to a value on the Kelvin scale that measures the color temperature of lights. The higher the K value, the more intensely bright and blue the light.

Large cities such as Houston, New York, and Seattle have installed 4000K LED streetlights with brightness as strong as midday light. Smaller town Davis, California, installed similar ones, but distressed citizens demanded that the bulbs they experienced as spotlights be replaced at great cost.

The 4000K lights cause concern significant enough that the American Medical Association adopted an official statement about the intensity of nighttime lights. In a nutshell, the message is to cool and dim them, because there’s a close connection between light and human health.

The AMA strongly cautions against outdoor lighting above 3000K. The 4000K lights cause severe glare, and sufficient levels cause retinal damage. Although it’s doubtful that anyone in Galveston will stare at these bulbs to cause such damage, it’s equally doubtful that glaring lights will make driving or walking safe at night.

Lighting the night brightly with blue-white light can also disrupt sleep in people and animals. It’s part of a concern that some call light pollution. Disturbed sleep and waking cycles affect hormone production, especially in teens, and can be associated with health conditions such as breast cancer and cardiovascular disease.

Engineers have proposed design solutions to lessen the negative impact of highly intense light. These include shields that make less of the bulb visible and use of the dimming function that’s possible with LED lights. The AMA advises that communities dim even 3000K lights after peak usage. Cambridge Massachusetts does so after midnight.

Experts who support the growing trend toward installing LED lights cite the legitimate need for energy efficiency. But they also stress the need to lessen human risk from overly intense lights. Installing 3000K LED bulbs, just 10 percent less efficient than 4000K, can meet both needs.

Now less clueless about the meaning of the K value, I hope to avoid being sleepless. And in case anyone wonders, as I did: The Kelvin scale for color temperature is named after engineer William Thomson, 1st Baron Kelvin, who lived decades before the scale would become central to our discussion.

Suzanne Peloquin lives and works on Galveston Island.


(13) comments

Ron Binkley

I never knew a light bulb could be so technical!

Don Schlessinger

Excellent discussion Suzanne, thank you. I wonder if anyone on our CC will this article?

Don Schlessinger

OOPS: read this article.

Steve Fouga

I love this article!

Whenever I read about a future project like the Ike Dike, the Stewart Beach pavilion, various Galveston Island drainage solutions or, in this case, lighting, I always assume that before acting on the first idea that comes along, a proper engineering study will be done, and the results used to guide the project (tongue firmly in cheek).

Surely the city will eventually decide on the proper color temperature in each location, based on best engineering practice, right? If that's not the direction they were heading, maybe Suzanne's article will nudge them in that direction.

George Croix

Good article.
It's fact that around 2700 to 3000K lighting gives of a fairly warm, easy to see with light
But something else to keep in mind is the lights under discussion are not being installed to provide a better sleep for people and animals.
They are being installed for safety.
That's the PRIMARY purpose.
Here's a thought.
Rather than blow the whole budget by mass purchase of one specific type light, why not get a couple of different brightness/light color ranges, and install one set for a couple blocks (enough distance to notice a difference) , then skip some blocks and install the different ones, then see what is most favorable to the folks actually exposed to them at night. Worst case, you end up with a few bulbs that are less favorable, and those could be put out at a least used location.
Actually looking at the light produced is a LOT better than takking any recommendations for it.
At the refinery, those gawdawful yellowish sodium vapor lights were the darlings of the folks who installed them, then the same folks never worked at night and had to try to SEE with that yellow cast lighting.
Hence the suggestion to poll the users, not the designers.

Rusty Schroeder

I like the new street signs along Broadway at the major intersections, I think they are bright and look sharp. In my opinion, since Galveston is a tourist town, good lighting is a must for people to know where they are at. I like the new LED lights I have seen in other cities and street lights in Galveston. The lights in Texas City along Palmer and down 6th have changed the look of that area for the better.

David Schuler

This article seems to equate intensity and color temperature and we have all grown up with light sources that behave so - incandescent lamps go from red to yellow to white as more power is applied and do the reverse when dimmed. The sun appears to do this, not because of power but because of atmosphere effect. Red light = dim, white = intense.
LED bulbs output the same color temperature whether dimmed or at full intensity. Turn on one with a dimmer and it's the same color no matter the setting. So it's easy to reduce the intensity of any LED streetlight, whether by an electronic dimmer or physical shields and doing so won't affect the color temperature.
The reason that 4000K lights are problematic is that pretty much all light-sensitive creatures have evolved to understand that 4000K light = daylight = daytime, and this can have a detrimental effect on behavior. We can see just fine at both colors, so in general 2800K is 'better' for the environment. When first released, 2800K bulbs were significantly less efficient than 4000K bulbs, but that is no longer true.

Steve Fouga

This might be the most informative thread I've seen during my short time on this forum. [thumbup]

Ron Woody

But how will it affect the turtles? :)

Steve Fouga


Jim Forsythe

Since you asked for it, here it is.
VOLT® 3W Turtle Safe Amber LED Bi-Pin (20w Halogen Replacement)
VOLT® LED bulbs are designed to match the form factor and illumination of the incandescent bulbs they replace. We have created these to counteract the effects of light pollution near beaches causing turtles to come inland where oftentimes they perish. Instead; with turtle safe lights, the turtles will safely return to the ocean where they belong.
These lamps are instant-on. They are within the required nanometer range of 590-605 to protect the sea turtles for which they are designed. This wavelength of light provides adequate lighting for humans while remaining virtually invisible to the turtles. Each lamp has an estimated life of 40,000 Hrs.

Wayne Holt

I totally agree with David S and George's take on color temperature, with the lower temp range a much better choice, IMHO. When discussing safety, harsh lighting can actually work against you, throwing high contrast shadows where a less brightly lit area would be easier to assess for a threat.

Human beings are pattern recognition sensitive; that's why a rope can look like a snake under certain lighting conditions. If you even out the lighting you make it easier to adjust from lamp lighting to less or no lighting; with a 4000K illumination in the blue spectrum, I would expect it to be harder for eyes to adjust when looking at less brightly lit areas. Exactly why you throw a flashlight spot into the eyes of an intruder.

Besides the utility of lighting, we should remember that there are serious considerations ongoing about making Galveston more appealing. The mayor was right in saying that lighting should be a big part of what is being planned. With the lower temp lights, you bring a more pleasing and people-friendly ambiance to any area you illuminate while not sacrificing the safety function.

Jeff Patterson

The LED lights being installed in the East End are 3000K, which I believe is the standard, at least for the lights I’m aware of in Galveston

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