Light spilling beyond the area it is meant for, measured as illuminance at the property line, often vertically at eye height facing the source. Ordinances set limits by zone, and complaints about sports fields, car dealerships and security lights are a common source of disputes. It is controlled with optics that cut backlight, shields, aiming, mounting height and curfews.
Neighbor's bedroom gets 4 lux vertical from the dealership poles, that's light trespass well over the residential limit.
Also heard as
- trespass
Do not mix it up with
- Spill: Spill is any light outside the intended target; light trespass specifically means it crosses onto someone else's property.
Related terms
Spill
Light that falls outside the area it is aimed at, onto walls, ceilings, audiences or neighbors.
BUG rating
An outdoor luminaire rating for backlight, uplight and glare, each scored 0 to 5, used in light pollution ordinances.
Cutoff
The angle above which a luminaire emits little or no light, used to classify glare and light pollution control.
Illuminance
The amount of light falling on a surface per unit area, measured in lux or foot-candles.