What is Dark Sky Lighting?

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By Sue Pipal

Here in Tahoe, we take it for granted that we can look up on a clear night and see a sky full of thousands of dazzling stars. Communities all over the world, however, are increasingly worried about diminishing sky visibility. In dense cities and suburbs where a mix of streetlights, shopping center lights, and household exterior lighting flood nighttime ground level with ambient light, it is becoming increasingly difficult to see the stars. In fact, the night sky over many cities is hundreds of times brighter than the natural starlit sky.

That’s why DarkSky International, based in Tuscon, Arizona, is fighting to keep communities like Truckee and Tahoe’s North Shore dark. DarkSky is attempting to educate us on outdoor light pollution, or the human-made alteration of outdoor light levels from those occurring naturally. According to DarkSky, light pollution disrupts wildlife, impacts human health, wastes money and energy, contributes to climate change, and blocks our view of the universe. 

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Just as we’re always fighting the good fight to keep our gorgeous lake clear and blue, it’s equally important that we work to keep our night sky black. It would surely be a loss if our amazing starry sky visibility was diminished and dulled. Both residents and guests come to Tahoe/Truckee for the beauty of our forests, mountains, waters, and skies. We need to be vigilant in keeping nighttime artificial light levels low for the pleasure, good health, and quality of life for all of us. 

Our wildlife and forests deserve this protection as well. It’s not just about beauty. Well-documented scientific research shows the devastating impact of light pollution on virtually all flora and fauna. Too much night light can be harmful to the natural ecosystems of plants, animals, and insects. Birds use stars to help guide them during migration. Darkness helps the animal population to hide from predators. Insects often flock to artificial nighttime light, which can be fatal and impact entire ecosystems. As for us humans, bright lights at night can lead to interrupted sleep patterns, which harm our health. 

There are several things you can do. First, you can turn off exterior light fixtures whenever you are not actually using them. Use motion sensing lighting where possible. And make sure exterior lights go off for good by 10 p.m. Further, turn off excess lighting inside the house that may be adding to outside light levels by shining through windows. This will not only help darken our skies but save you money, too. It’s estimated that in the U.S. alone, consumers pay $3.3 billion annually in excess energy charges. 

Additionally, you can swap out old, out-of-date fixtures that shine light upward toward the skies to new, modern ones that are not only more energy efficient, but significantly reduce the broadcast of artificial light. Luckily, exterior lighting manufacturers have been working on this problem for some time now. Where light fixtures once shone upward, downward, and outward, new lighting has been developed to shine downward only. These new LED light sources shield light from pointing upward and direct light downward in compliance with dark sky regulations. Here again, energy efficient LED lighting will save you money on your electric bill. Thirty percent of outdoor lighting is wasted by lights that aren’t shielded. 

SEEING STARS: Examples of shielded light fixtures from the Town of Truckee’s municipal code. Image courtesy Town of Truckee

Dark sky lighting is typically a warmer lighting as opposed to a traditional, white/bluish light that is brighter and more glaring. Dark sky lighting is typically in the range of 2,500 kelvins to 3,000 kelvins color temperature with older lighting at about 4,000 kelvins. The lower the score, the longer the wavelengths, which creates the warmer, less intrusive light.

Many of our local Tahoe/Truckee neighborhoods do not require dark sky lighting on existing buildings, although some homeowners associations do. As for new construction, requirements vary by locale. 

The TRPA specifies that all parking lot, walkway, and building lighting be directed downward. This would affect all new construction and remodels in the Tahoe Basin. As Jeff Cowen of the TRPA says, “TRPA’s codes typically only come into effect through the permit process. So, yes, the new lighting standards will take time to be incorporated fully.” 

Placer County does not have a dark sky ordinance or regulations, although many homeowner associations in Truckee like Sierra Meadows and Martis Valley do, and the county highly encourages residents to be dark sky compliant. Inside the Tahoe Basin, however, Placer follows TRPA’s dark sky requirements.

As for the Town of Truckee, dark sky lighting is required on new construction and remodels, but existing homes are not affected by these requirements. Truckee looks at several factors in developing appropriate lighting for projects — over-lighting, energy waste, sky glow, glare, and light trespass onto neighboring properties. They require fixtures that are fully shielded, which shield “in such a manner that light rays emitted by the fixture, either directly from the lamp or indirectly from the fixture, are projected below a horizontal plane running through the lowest point on the fixture where light is emitted,” according to the town’s building requirements document.

As for existing houses that are not undergoing construction, the town is encouraging homeowners to swap old lighting for new, downward facing and energy efficient fixtures with a $75 rebate per fixture for up to eight fixtures per home. There is also a $50 rebate for commercial buildings for up to 50 fixtures. 

South Lake Tahoe is also affected by TRPA requirements which apply to the entire Basin. It’s interesting to know, however, that the city itself is making an effort to update its own fixtures. In May 2023, South Shore began a program of converting public lighting along the Highway 50 corridor into dark sky-compliant lighting. The city owns over 900 pedestrian light fixtures along roadways, walkways, parks, and trail networks.

~ Sue Pipal owns Dragonfly Designs in Tahoe City and tahoedreaminteriors.com. She works in all design styles including contemporary, but has a special fondness for Old Tahoe style and loves to mix modern conveniences and comfort with whimsical antiques and charming old lodge-style pieces that give the family cabin that welcoming look of “collected over generations.” 

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1 COMMENT

  1. Truckee and other jurisdictions should mandate downward lighting in existing STRs. STR users seem to be particularly likely to keep floodlights on at night and particularly oblivious to the effect of light trespass on the neighbors.