Software Measures Light Pollution, Optimizes Lighting Design
In response to the growing concern of light pollution in urban areas, researchers have developed a system that automatically measures light pollution and optimizes lighting design. This quantitative data is the first published information that the researchers know of showing how much light escapes from outdoor lighting installations.
Called Outdoor Site-Lighting Performance (OSP), the system helps engineers plan lighting designs in commercial areas, and can also help homeowners optimize their outdoor lighting. As Mark Rea, lead developer and director of the Lighting Research Center at Rensselaer Polytechnic Institute explains, too much lighting can cause problems for human and animal health (such as making it harder to sleep well) as well as making stargazing less enjoyable. Too little light can compromise an area's safety and security.
The researchers identified three factors in light pollution: sky glow (the total amount of light leaving a property), light trespass (the amount of light crossing from one property to an adjacent property), and glare (the amount of light that causes discomfort to human eyes). The OSP system quantifies each factor, each of which is independent of the others.
To find out the amount of light pollution in an area, the software establishes a "box" around the property line and up to a certain height (10 meters is the standard, or the highest point on a taller building). Then the system measures the three factors: the average luminance on the sides of the box gives the sky glow, the maximum luminance on the sides gives the light trespass, and three luminance values calculated at the property line give the glare.
Using this system, the scientists studied 125 lighting designs for four common nighttime lighting applications: car parking lots, roadways, sports fields, and plazas. The researchers hope that the software will help manufacturers (who initially approached the team requesting a light analysis system in 2005) to compare different lighting design alternatives and experiment with creative lighting solutions.