Streetlighting Concerns

I submitted the following letter to the editor to the Dodgeville Chronicle this evening:

Dear Editor:

Have you noticed the gradual transformation of our streetlights in Dodgeville, Mineral Point, and other communities in SW Wisconsin?  The light source in our streetlights is changing.  High Pressure Sodium (HPS), which has been in use for decades and produces a orangish-white light, is being replaced by light emitting diodes (LEDs), producing a whiter light.

What’s not to like?  LED’s many advantages include: efficiency, longevity, instant-on and instant-off, and dimmability, to name a few.  But Alliant Energy is installing new streetlights that produce white light that is too blue, and the illumination levels are about 2.6 times as bright as the high pressure sodium streetlights they are replacing.

Lighting specialists use a term called “correlated color temperature” or CCT (in Kelvin) that allows us to compare the relative “warmness” (redder) or “coolness” (bluer) of  various light sources.   The illumination provided by candlelight has a CCT around 1500 K, HPS around 2000 K, an incandescent light bulb around 2800 K, sunrise/sunset around 3200 K, moonlight around 4700 K, and sunny noon daylight around 5500 K.  The higher the color temperature, the bluer the light.

Higher color temperature illumination is acceptable in workplace environments during the daylight hours, but lower color temperature lighting should be used during the evening and at night.  Blue-rich light at night interferes with our circadian rhythm by suppressing melatonin production, thus reducing sleep quality, and several medical studies have shown that blue light at night increases the risk of developing cancer, most notably breast cancer.  Even low levels of blue-rich light at night can cause harm.  While it is true that something as natural as moonlight is quite blue (4700K), even the light of a full moon provides an illumination level of just 0.01 foot-candle, far dimmer than street lighting, parking lot lighting, and indoor lighting we use at night.

LED streetlights are available in 2700K, 3000K, 4000K, and 5000K.  I believe that Alliant is installing 4000K streetlights in our area—I certainly hope they are not installing any 5000K.  What they should be installing is 2700K or 3000K.  These warmer color temperature lights are no more expensive than their blue-white counterparts, and the slightly higher efficiency of the blue-white LEDs is entirely nullified by over-illumination.

Even considering a modest lowering of light level with age (lumen and dirt depreciation), these new LED streetlights are considerably brighter than the HPS lights they are replacing.  Just take a look around town.  What is the justification for higher light levels in our residential areas, and when was there an opportunity for public input?  In comparison to older streetlights, the new LED streetlights direct more of their light toward the ground and less sideways or directly up into the night sky, and that is a good thing.  But now the illumination level is too high and needs to be reduced a little.

If you share my concerns about blue-rich lighting and illumination levels that are often higher than they need to be, I encourage you to contact me at oesper at mac dot com.  I operated an outdoor lighting sales & consulting business out of my home (Outdoor Lighting Associates, Inc.) from 1994-2005, and wrote the first draft of the Ames, Iowa Outdoor Lighting Code which was unanimously adopted by the city council in 1999, so I am eager to work with others in the Dodgeville area who are also interested in environmentally-friendly outdoor lighting.

David Oesper
Dodgeville

Pet Peeves

Here is a list of 10 irritations, in no particular order, that make me feel like an alien on my own planet.

  1. High color temperature headlights – Traditional automotive headlights have a yellowish-white color temperature of 3200K. Xenon headlights emit a bluish-white light around 4500K. LED lights are even bluer at around 6000K. These new “blue” headlights make me want to give up night driving altogether. They are too glary and too bright for oncoming traffic. Add in the same for so-called “fog” lights, and the result is often blinding for other drivers.
  2. High color temperature LED lights – While we’re on the topic of lighting, most indoor and outdoor LED lighting should have a color temperature between 2700K and 3000K. This provides a soothing yellow-white light instead of the garish and glary blue-white LED lights in common use today with a color temperature of 4000K or even higher.
  3. Dusk-to-dawn lighting – With the availability of modern light sources, control, and dimming technologies, most outdoor lighting does not need be on or running at full brightness all night long.
  4. Television advertisements – I don’t know how anyone can stand to watch television because there are so many advertisements. I’ve given up watching anything that has advertisement propaganda embedded within the program.
  5. Dystopian movies and television programs – Why would anyone find a dystopian portrayal of the future entertaining or even desirable? I find it utterly horrifying and we should do everything possible to make sure such a future never occurs. Furthermore, I find the amount of violence and aggression in movies and television appalling. This is entertainment? No thanks, I’ve got better things to do with my time.
  6. TV Screens in Restaurants – When I’m dining at a restaurant, just about the last thing I want to see is the distraction of one or more television screens. I’m there to enjoy the food and the company I’m with and screens of any kind are intrusive.
  7. Overuse of smartphones – So many people seem addicted to their smartphones. I don’t generally use one and get along just fine. As much as I use computers in my everyday life, I don’t want one with me everywhere I go. I am really thankful I grew up before personal computers and smartphones existed. Gives one a different perspective.
  8. Sports – I have absolutely no interest in sports. Physical fitness and healthful living, yes, but sports seems like a big waste of time. I don’t see how so many folks can get so excited about something that does absolutely nothing to make the world a better place.
  9. Hunting – I don’t see how anyone can derive pleasure out of depriving another animal of its life. It’s just sick. It is one thing to kill an animal if it is necessary for survival, or self-defense, but for sport it is disgusting. For necessary animal population control, why not use high-tech science-based birth control methods instead?
  10. Pets – I love seeing animals in nature, but have no interest in owning or taking care of a domesticated animal. I much prefer solitude or the company of people. I’m too busy to have any time for a pet, anyway. Don’t like it when you visit someone and their dog or cat jumps on you or licks you. Yuck.

Blue Light Blues

One by one, all of our warm white lights are being replaced by cold, harsh, bluish-white LEDs.  And it is happening fast.

Everywhere.  In our streetlights, our workplaces, even our homes.  How do you like looking into those blue-white vehicle headlights as compared with the yellow-white ones we have been using since the automobile was invented?

LED lighting is the way of the future, don’t get me wrong, but we should be specifying and installing LED lights with a correlated color temperature (CCT) of 2700K or 3000K—with few exceptions—not the 4000K or higher that is the current standard.

Why is 4000K the current standard?  Because blue-white LEDs have a slightly greater luminous efficacy than yellow-white LEDs.  Luminous efficacy is the amount of light you get out for the power you put in, often measured in lumens per watt.  But should luminous efficiency be the only consideration?  What about aesthetics?  In addition to luminous efficacy, there are other, more significant ways to reduce power consumption and greenhouse gas emissions:

  • Use the minimum amount of light needed for the application; no need to overlight
  • Use efficient light fixtures that direct light only to where it is needed; near-horizontal light creates annoying and visibility-impairing glare and light trespass, and direct uplight into the night sky is a complete waste
  • Produce the light only when it is needed through simple switches, time controls, and occupancy sensors; or, use lower light levels during times of little or no activity

Even the super-inefficient incandescent light bulb (with a CCT of 2400K, by the way), operating three hours each night uses less energy than the light source with the highest luminous efficacy operating dusk to dawn.  Think about it.

In my town, as in most now, the soothing orange 1900K high pressure sodium (HPS) streetlights are being replaced with 4000K LEDs.  That’s a big change.  It will completely transform our outdoor nighttime environment.  Warm-white compact fluorescents are 2700K, and even tungsten halogen bulbs are 3000K.  Do we really want or need 4000K+ LEDs?

We are currently witnessing a complete transformation of our illuminated built environment.  Not enough questions are being asked nor direction being given by citizens, employees, and municipalities.  The lighting industry generally wants to sell as many lights as possible at the highest profit margin.  We as lighting consumers need to make sure we have the right kind of light, the right amount of light, and lighting only when and where it is needed.

Higher color-temperature lighting of 3500K or higher is often specified for office lighting during the day to more closely match daylight color temperature, but all to often this type of lighting is also being specified for nighttime use.  Lower color temperature lighting of 2700K or 3000K should be used for residential lighting and any other lighting that is primarily being used after sunset, such as streetlighting, parking lot lighting, and security lighting.

Bad Lighting at Dodgeville High School

At a school board meeting in November 2017, concerns were raised about inadequate lighting for evening school events, so the Dodgeville School District directed Alliant Energy to install some additional lights.  The lighting was installed during a warm spell in January 2018, and the photographs you see below were taken during the afternoon and evening of June 17, 2018.

Rather than being used only when school events are taking place in the evening, these terrible lights are on dusk-to-dawn 365 nights a year.  They are too bright, poorly directed, poorly shielded, and the glare they cause on W. Chapel St. and N. Johnson St. could pose a safety concern for pedestrians not being seen by drivers experiencing disability glare.  I can imagine that adjacent neighbors are not too happy with the light trespass into their yards and residences, either.

This is a perfect example of poor lighting design and unintended consequences.  How could it be done better?  Look for the solution below the following series of photos documenting the problem.

Bleacher path floodlight produces a great deal of uplight, and illuminates the disc golf course far more than the bleacher path

Bleacher path floodlight is mounted in a nearly-horizontal orientation

Bleacher path floodlight

Bleacher path floodlight

Bleacher path looking towards the bleachers

 

Bleacher path looking towards W. Chapel St.

 

Bleacher path at night

Bleacher path floodlight lighting up the disc golf course. Also note how much brighter the illumination is from the newly-installed blue-white LED streetlight as compared with the orangish light from the older high pressure sodium (HPS) luminaire.

Bleacher path floodlight lighting up the disc golf course and basket

Large tree being brightly illuminated all night long with bleacher path in foreground

Sub-optimal parking lot lighting at Dodgeville High School

Overflow parking floodlight

 

Two additional overflow parking lot floodlights

Overflow parking floodlight

 

Overflow parking floodlights

 

Overflow parking floodlight glare and spill light

 

Overflow parking floodlight glare onto W. Chapel St. in Dodgeville

Overflow parking glare and spill light onto W. Chapel St. in Dodgeville

Solutions

Pedestrian-scale 2700K LED “soft” lighting could be installed along the bleacher path

https://i2.wp.com/www.rabweb.com/images/features/ledbollards/bollard-hero.png?resize=840%2C615&ssl=1
Or vandal-resistant bollards could be used—even low voltage lighting

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If floodlights must be used, shield them, point them more downwards, and turn them off after 11:00 p.m. each night (or have them on only while evening school events are in progress)

In fact, regardless of the lighting solution, the lights should be either turned off or dimmed down to a lower level later at night.  (Security cameras will see just fine at lower light levels if that is a concern.)

Good neighbor outdoor lighting means minimizing GLUT:

Glare—never helps visibility
Light Trespass—no point in putting light where it is not needed
Uplight—sending light directly up into the night sky is a total waste
Too Much Light—use the right amount of light for the task, don’t overlight

The LED Lighting Revolution

Solid state lighting, namely light-emitting diodes (LEDs), are completely revolutionizing indoor and outdoor lighting.  Here’s why:

  1. White LEDs on the market today have a system luminous efficacy ranging from 50 (least efficient) to 80 (average) to 140 (most efficient) lumens per watt.  This far exceeds the luminous efficacy of incandescent (5-35 lumens/watt), and generally exceeds compact fluorescents (45-60 lumens/watt).  Prototypes of the next generation of white LEDs have luminous efficacies up to 150 lumens/watt, and theoretically 200-250 lumens per watt may someday be achievable.  Since the traditional white light source of choice for outdoor lighting has been metal halide with a luminous efficacy of 65-115 lumens/watt, white LEDs are well on the way towards replacing metal halide.  Even the more efficient orange high pressure sodium (HPS) lights, with an efficacy of 150 lumens/watt, are nearly matched by the best white LEDs.  Only monochromatic low-pressure sodium (LPS) with an efficacy of 183-200 lumens/watt will give more lumens per watt than the best white LEDs.
  2. White LEDs last much longer than other light sources: 50,000 to 100,000 hours (between 12 and 24 years, operating dusk-to-dawn 365 days a year).  In comparison, high pressure sodium typically lasts about 5 years, and metal halide a little less at 4 years.
  3. Unlike high-intensity discharge (HID) sources such as metal halide, HPS, LPS, and mercury vapor, white LEDs are “instant on / instant off” with no warmup time to full brightness, so they can be switched on and off as often as you like with no shortening of bulb life; and they are easily dimmable. LEDs will render dusk-to-dawn lighting a questionable option rather than an operational necessity.

My only concern is that we finally “get it right” with LEDs instead of blindly following the “more is better” philosophy as we have with every lighting efficiency improvement in the past.  Low levels of white light (fully shielded to minimize direct source glare) is the most effective and efficient way to provide adequate illumination.  This shouldn’t come as a surprise, however.  Think of the light provided by a full moon as we have this week.

Unfortunately, most places that is not what is happening.  Light levels are increasing, as is the amount of lighting.  We seem well on the way towards eliminating anything resembling a natural nighttime environment for most people.  I don’t know about you, but that is not a world I want to live in.

References
DIAL (15 June 2016). Efficiency of LEDs: The highest luminous efficacy of a white LED.  Retrieved from https://www.dial.de/en/blog/article/efficiency-of-ledsthe-highest-luminous-efficacy-of-a-white-led/.

Kyba, C., Kuester, T., et al. 2017, Science Advances, 3, 11, e1701528

Two Predictions About Outdoor Lighting Technology

Here are my (ever hopeful) predictions about the future of outdoor lighting technology.

(1) Dusk-to-dawn lighting will soon become a thing of the past.

Ever see the irony that as outdoor lighting efficiency has greatly improved over the last several decades, we have moved from “light only when you need it” to “lights on all night long”?  An incandescent light, if operated less than 3 hours per night, will use less energy than even the most efficient light source operated dusk to dawn.  Yes, that’s right.  Three hours of incandescent light (which is horribly inefficient) each night throughout the year uses less energy than an LPS, HPS, Metal Halide, or LED source of comparable lumen output operated dusk-to-dawn.  Just think of the energy savings we could realize by using an efficient light source that is used only when it is needed!

Passive infrared (PIR) switches, which are rather prone to false triggering, will be replaced by image analysis software that will do a much better job of deciding when a light needs to be on and when it does not.

The HID (high intensity discharge) light sources in common use today such as HPS (high pressure sodium) and metal halide have two drawbacks.  They prematurely age if you frequently turn them on and off, and they take a while to reach full brightness after having been off for a while.  These drawbacks do not exist with efficient “instant on” sources such as LEDs, which are even dimmable.

These new technologies in lighting and control will make it both easy and affordable to have reliable light only when it is needed.

(2) Security lighting will soon be replaced by much better crime prevention technologies.

Soon, flooding a premises with light will be one of the WORST things you can do to deter and prevent crime.  As security systems improve and become more sophisticated and affordable, security lighting will only be needed when an intrusion is detected, and maybe not even then if you want the perpetrator to be detected without them knowing they have been detected.  Fixed visual recognition systems or even mobile peripheral devices (MPDs)—as Bill Gates likes to call “robots” to avoid all the anthropomorphic connotations—that operate with ambient light (visible, infrared, etc.) will soon obviate anything so primitive as security lighting. And, if the stationary or mobile sensing device is inactivated by a hostile (or non-hostile) event, its connection with the base station inside the home or business would be broken and appropriate action could be immediately taken.

As both lighting technology and lighting control technology improve, it is my hope that dusk-to-dawn lighting will be rendered obsolete.