Being able to see the night sky is something nearly everyone enjoys. In areas that are populated, lighting is necessary for our safety on the roads and in our neighborhoods.
Unfortunately the lighting designs of the past didn't have the night sky in mind as cities were growing. Street lights with globes, though often directed, had acrylic or glass globes that refracted light upwards. Many companies claim dark sky compliance by adding a solid spun aluminum top to these type of fixtures. These fixtures are not dark sky compliant as there is still a measured amount of uplight. This is also true for many pendants or teardrop styled fixtures that have a lens that drops below the brim.
Dark sky lighting encompasses being able to see the stars, making sure light goes where it's needed and reducing glare. Today there are many decorative street light designs that offer all of these dark sky benefits while still lighting our roads adequately for safety. These are offered in post-top and pendant style lighting, where as in the past, pendants were the only way to get a true dark sky approved street light. With the emergence of dark sky compliant post top fixtures, dark sky friendly assemblies become less costly as you no longer need an arm to hold a pendant fixture.
Another topic that often comes up when discussing dark sky lighting is kelvin temperature. Kelvin temperature is simply the color the LED is producing. When LED was first introduced, for it to be efficient it had to be extremely white, or around 5000 kelvin. This was in stark contrast to what street lights were before with high pressure sodium, which was a much warmer color. Today, LED's have come a long way and we are able to get those warmer colors without sacrificing efficiency. We often recommend being much closer to those warmer colors of 3000 kelvin or even down to 2700 kelvin. Not only is there a higher level of comfort at these levels, but there are reported health benefits when keeping LED's at these kelvin temperatures. For humans, white light can disrupt our sleep patterns, just as you hear about our cell phones causing problems with our sleeping habits.
Too white of light can also affect nocturnal animals and the way they go about their lives. Lastly, the lower kelvin temperatures produce less glare, which in turn creates a better environment when concerned about dark sky conditions.
Street lighting technology has come a long way in allowing us to have dark sky lighting in many different styles. If dark sky lighting is something that is important to your city, with new technology you can still keep your roads safe while keeping the skies dark.
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