Light Pollution: Are you Part of the Problem?
Light pollution is "the glare from inefficient outdoor lights, especially around highly populated areas, making it difficult to discern the features of the night sky" and chances are that you’re part of the problem. *
If you live in the heart of a large American city, it’s entirely possible that you could spend most of your life without seeing any more than a handful of stars due to the skyglow that city lights create over the urban area. It’s not that the stars aren’t there. The billions of stars of the Milky Way shine brightly over Manhattan, but its beauty is completely obliterated by the blanket of light that the city creates underneath. Ask anyone who has been in a city during a massive power outage how beautiful the sky instantly became.
It’s easy to pass the problem off as due to the car lots, the stadiums, the shopping center parking lots, gas stations and street lights that blast out excess light, and it’s true that control of light pollution is a regional problem that can’t be solved by managing your porch light – but it’s a start.
Planning for outdoor lighting isn’t tough, it’s simply deciding where you need light to go and then selecting a fixture that will do that without sending extra light to places where it’s not needed – or wanted. Most lighting fixtures try to be as versatile as possible by directing light down, out and sometimes up so that they’ll shine wherever you might want your need is. But because it’s not directed, you end up using more energy than needed and waste a lot of light. Think of a typical front door. We mount lights on the wall by the door that shine right in the faces of approaching guests. How welcoming is that?
Much better is to illuminate only the areas that need it and to concentrate the light there. Just doing this has several positive outcomes:
1. Energy is saved;
2. Light pollution is decreased;
3. Light trespass (lighting your neighbor’s property) is reduced;
4. Safety is increased.
We all hate the glare that comes from an approaching car with its high beams on. It causes our pupils to contract so that when the light passes, we’re blinded for a moment until our eyes readjust to the night. Glaring house lights have a similar result and create harsh shadows where it’s easy for things to be unseen. When glare is avoided and illumination is uniform, visual perception is greatest.
So what kind of light fixture should be used? Very simply, one that directs light downward, is focused and not above the horizontal plane. This can be done with a fully shaded fixture or by mounting recessed lights in a porch ceiling or eave, using the structure of the house as a shield. This approach can be used at your home or entire neighborhoods and communities can tackle it for impressive results.
The first example shows a home with fully shielded wall lights that place light on the porch floor where it’s needed in a dramatic fashion.ã
The second photo shows a front porch with lights mounted in the ceiling. The lights are shielded by the frame of the porch and provide a soft and welcoming glow to the house. And although a second, evenly spaced ceiling light could have been used on each floor without being a problem, you could still easily sit outside on the upstairs porch and read.
Below is a before and after example of a typical wall mounted lamp replaced with a shielded one. The same light bulb was used in each photo. Note that with the improved lamp the light bulb does not extend below the bottom of the fixture, the house window is no longer lit up, light isn’t shining in the windows of the door and the walk in front of the door is actually better lit. There’s no glare, you can still look through the door windows and see who’s coming, but the visitor is no longer getting blinded.
Controlling your home lighting is only a small step toward decreasing light pollution. But many small steps make for great distances travelled. See one community’s response to controlling light pollution at: http://www.infobarrel.com/Central_Florida_Light_Pollution_and_the_Town_of_Harmony
* www.dictionaryofconstruction.com/definition/light-pollution.html; 11-19-2012