A pub owner was recently asked to take down the LED parking lot lights he installed to light his parking lot. The lights were installed after complaints about the lack of light. However, he started receiving different complaints! One neighbor complained to the city council that the 16 foot high white LED lights shine into her bedroom and make it difficult to sleep.
She said, “I feel that local residents needs would be better served by the floodlights being replaced with lights of a more considerate design, height and light intensity.” The city intervened and decreed the LED area lights have to come down, adding the lights have an “unacceptable overbearing and visually intrusive impact” on area residents.
What went wrong here? I, Dr. Bulb, enjoy a well-lit parking lot, but was this such? Were the LED parking lot luminaires the issue? Was the neighbor unjustified in her complaints? To answer the last question, probably not. She was a victim of light trespass.
Light trespass is basically light emitted by a luminaire that lights an area where the light is not wanted and probably not intended. In this case the bright light may have been welcome in the parking lot but not on her pillow. The height of the luminaires was probably not the issue. Most likely the way the luminaires were being used was the issue.
If the luminaires were higher and aimed down in a dark-sky compliant manner, the light would be well distributed and be emitted in an area under and around the luminaire. If the luminaires were aimed across the lot, in an attempt to light the lot with a few fixtures, the light will go across the lot and continue on to other people’s property. The result would obviously be infuriating. If the light was the type that throws light 360 degrees, it obviously would end up everywhere.
What the pub owner should have done is had a photometric analysis done for his parking lot. The photometric analysis should take into consideration the foot candles required in the lot by code, light trespass generated by the light, and if there any other ordinances restricting lighting such as dark sky compliance. Then, complying with local regulation and after attaining a permit to proceed with the work, the pub owner could have the parking lot lighting installed.
Simple? Simple enough if approached correctly.