There are just four basic principles of responsible outdoor lighting. They are to use artificial lighting only:
1. Where it is needed, which means using properly directed and shielded fixture(s) that can target light – usually with zero up-light (no light directly into the sky) and not onto neighboring property.
2. When needed, which means using timers, motion sensors and/or switches as appropriate to light the target area only when it is useful to do so. Rarely is it useful to burn outdoors lighting all night.
3. In the amount needed. The Illumination Engineering Association has recommendations for how much light is required for most applications. Over-lighting wastes energy, generates unnecessary carbon, sky-glow along with other pollutants, and can reduce visibility into adjoining areas. Outdoors, when some light is good, more is at best a waste and maybe worse.
4. In the color needed. Blue light at night involves particular health and environmental risks and creates more sky-glow. While blue light can be good in the daytime, for high-resolution work and maximum alertness, night lighting should minimize blue content consistent with the task. Typically a warm or soft white light is more than sufficient for most outdoor purposes. These typically have correlated color temperature ratings (CCT) of 3000 degrees or less. All white light has some blue content. Where color rendition is not needed, an amber (bug light) is ideal. No blue light and it will not attract bugs, leaving them in your garden to pollinate instead of dying at your fixture will mean no bug carcasses to clean up. (Hint: Indoor amber night-lights with photosensors are great in bedrooms and bathrooms for those needing light to navigate at night.)
The International Dark-Sky Association, in cooperation with selected lighting manufactures, makes it easy for most residential consumers to select appropriate fixtures for most purposes. IDA approved lights will be appropriately shielded. IDA has provided an online selection tool to help with selection, and IDA approved fixtures can be found at most places that sell outdoor residential lighting fixtures.
Those with commercial lighting needs should seek professional lighting expertise. Relying upon a utility company to provide lighting advice is not recommended. In most cases, their expertise is in selling electricity not designing lighting.
If you have further questions we are glad to help. Send your questions to firstname.lastname@example.org
Or, consult one of the Lighting Specialist listed as Friends of Responsible Lighting.