Embedded Files
Tech Tips to get you started...
Tech Tips to get you started...
Tech Tip – Controls
A key strategy to reduce the impact of artificial light at night (ALAN) is to only turn lights on when really needed. The current International Energy Code for commercial buildings requires many outdoor lights to be completely shut off in the middle of night when nobody is around and almost all other outdoor lights to be dimmed to 50% or lower. Each state has their own rules and not all follow the most current energy code but it’s a great guide for how to operate the lights you own. Motion sensors are one way to comply but if you are looking for other options another way is with a programmable control. The GE SunSmart timer pictured here replaces a standard light switch. This handy device will adjust on and off times automatically based on sunrise and sunset times and can also be programmed to shut them off entirely in the middle of the night. It’s not that expensive and can typically be installed by a qualified electrician in a few minutes. If your locality allows you to DIY things like switch replacements and you are capable of doing it safely and correctly it can also be a DIY installation. We’ll talk a lot more about controls in future Tech Tips so stay tuned!
Tech Tip - Bug Ratings
More about how to buy the right light. Today we’ll explain one of the other abbreviations you might see when considering what light to buy. The B.U.G. rating of the fixture is a way to know at a glance how much light is going behind the mounting point, how much up into the sky and how intense the light is when you look at it. Just like in golf the lower the score the better in every case. The B stands for Backlight and the lower the number the less light is pushed back against the wall for a wall mounted fixture. If you have a reason to light the face of the wall you might want a backlight value above zero but otherwise looking for a B0 rating makes the most sense. It will reduce the bright spot you see right below the fixture. The U stands for uplight and tells you how much light is pushed directly to the sky or nearly to the sky. You should only buy a fixture if it has a U0 rating. Otherwise, you know you are wasting money on light going where it isn’t needed. The G stands for glare. It’s a bit more involved than the other two but here’s the simple rule. Once you know how much light output your application requires (in lumens) pick the fixture that has the lowest glare rating for that lumen output. Higher lumen fixtures in general are always going to have a higher G rating than lower lumen fixtures which is yet another reason to go with the lowest lumens needed for the job. Photo of Photinus pyralis by Terry Priest (http://www.frfly.com/)
Tech Tip - How do you Verify Lighting Manufacturer Claims?
This post is aimed at the decision makers primarily for commercial work but it’s good for everyone to know anyway.
A manufacturer can make a lot of claims about any product and how would we know if they are true? Thankfully there’s an easy way to verify those claims – use DesignLights Consortium (DLC) Certified products. You have to create a free account to see the lists but you can search for lights by any number of criteria. DLC is used to verify product performance for many (if not most) of the energy rebate programs in the country.
As an independent non-profit organization, DLC provides decision makers with data and resources on quality lighting, controls, and integrated building systems to reduce energy, carbon, and light pollution.
And the exciting news that triggered this topic is their LUNA program launched two years ago. The DLC’s LUNA requirements establish criteria for using the highest quality outdoor lighting at night – lighting that minimizes light pollution, provides appropriate visibility for people, and limits negative impacts to the environment. Check it out here: https://www.designlights.org/our-work/luna
Tech Tip - Outdoor Lighting Tech Tips - Fixture CCTs
Previously we learned in general what Correlated Color Temperature (CCT) is and why it’s important to use the lowest possible CCT values for outdoor lighting at night. Today we’ll scratch below the surface just a bit and share some exciting news!
Here are two spectral power distribution graphs from actual LED light fixtures from a major manufacturer. The one on the left is a 2200K LED. On the right is a 4000K LED. Notice the large increase in the amount of blue spectrum lighting power in the 4000K LED. That’s why a typical 4000K LED has double the light pollution impact of a 2200K LED. The example shown is 69% worse than the 2200K.
The Relationship Between Sky Glow and CCT
Lighting science is complex and the relationship between CCT and relative sky glow impacts is not a perfect one. There is a better measurement - but it’s not listed on product specifications so we’ll keep using CCT for now.
What’s so Exciting about all This?
Three major developments around CCT have occurred in the past 12 months. At least one major LED chip manufacturer is now producing new LED chips with VERY little blue content (less than 2%) that have equivalent color rendering values and nearly equivalent efficacies to the much bluer existing technologies. And manufacturers are starting to sell fixtures using these chips at 2200K and some with CCTs as low as 1800K. Simultaneously the standards organization, ANSI, has released a new version of C78.377-2024: Solid-State Lighting Products which creates definitions for 1800K and 2000K CCT LEDs – something that previously didn’t exist! That allows manufacturers to build products to a defined standard and for organizations that test fixtures like the DesignLights Consortium to qualify them as meeting a national standard. This all may sound mundane and perhaps even trivial to those not familiar with the lighting industry but it’s far from it and opens the door to more production of high-quality, warm-CCT products in the future. These new developments along with the ever-growing body of research documenting the harms caused by blue spectrum light at night are already pushing manufacturers to move their products to warmer colors.
How Can I Help?
Talk to owners of existing high-pressure sodium outdoor lights and ask them to change to warmer LED options when they decide to upgrade to LEDs.
Properly selected 2200K and lower CCT LEDs will make the sky darker.
LEDs with 3000K and higher CCT will make the sky brighter.
Seek out warmer CCTs of 1800K, 2000K, and 2200K when you shop for outdoor LED bulbs and fixtures and specifically ask for them when shopping.
The availability of warmer CCTs is increasing monthly, and consumers asking for them will confirm demand for retailers and manufacturers and encourage more product development.
Stay tuned for more tech tips on outdoor lighting!
Scott Lind is a licensed electrical engineer and master electrician in Ontario, WI. He is currently serving as the President of the Kickapoo Valley Dark Sky Initiative
Outdoor Lighting Tech Tips - Correlated Color Temperature
What is Corelated Color Temperature (CCT)? It’s the way to describe the general color of light emitted by a source, whether artificial light or the sun. It's measured in units of Kelvin (K).
How is CCT created?
The visible light that we think of as “white” light is made up of a whole spectrum of colors that together create the color we see. That spectrum of wavelengths ranges from 400 nanometers (nm) to 700nm. 400nm light is very blue, nearly ultraviolet. 700nm is very red, next to infrared. In between are green, yellow and orange.
Why does CCT matter?
The CCT of sunlight that we see varies because of atmospheric interference and reflectance of the sunlight. During sunrise and sunset the CCT of sunlight is warmer, redder, than what we see during the rest of the day. That’s why, if we decide to install any artificial light for use at night it should be as warm (red) as possible. Our bodies and those of the millions of other species we share the planet with have adapted to the changing CCT of sunlight and respond physiologically to it. Blue light at night tells our bodies that it’s daytime – even though it isn’t. The warmer the artificial light the less impact.
In addition, and just as critical, is that reducing the amount of blue spectrum in light dramatically reduces atmospheric scattering. That scattering is sky glow and light pollution. Having blue lights on at night spreads the exposure to those disruptive wavelengths.
Next time we’ll talk about how LED manufacturers create the CCT of the lights they make and where the trends are headed.
With LED lights manufacturers can mix different proportions of each color to achieve the CCT they want.
Tech Tip - Watts and Lumens
More about how to buy the right light. Today we’ll explain how to translate Watts into lumens. Most people think about quantity of light in terms of Watts. A 40 Watt bulb, a 60 Watt bulb etc. Everyone kind of knows what that looks like and it’s easy when you go to the store. But when the lighting source changes that quick reference gets in the way of good decision making. LED fixtures vary in efficiency in converting watts to light but in general they put out more than 100 lumens for each Watt they consume. That’s about 10x the light of an incandescent bulb for the SAME Watts! When you buy an LED bulb or fixture take the Watts on the box and multiply by 10 to get an image in your brain about what that will accomplish for your application. The goal isn’t to buy as much light as you can. The goal is to buy the right amount of light and take advantage of the energy savings. Buy a dark sky LED instead of a “glare bomb” LED and save another 50% in energy year after year after year. Image Credit: Saint Louis City MO
"From campfires to computer screens, we have craved more light, not less. It is jarring for us to think of light as a pollutant, but it becomes one when it creeps into times and places it doesn't belong."
"From campfires to computer screens, we have craved more light, not less. It is jarring for us to think of light as a pollutant, but it becomes one when it creeps into times and places it doesn't belong."
Ed Yong, An Immense World (2022)
Page updated
Google Sites
Report abuse