Developed as a practical system for assessing outdoor lighting performance, the OSP method can be used with any commercial lighting software. Using this software, the designer establishes a calculation "box" following the natural division between a public and private space, the property line.
For purposes of standardization, scientists in the LRC set the top of every calculation box at 10 meters (33 feet) above the highest luminous architectural element on the property, or the highest point on a building that might be illuminated with flood lighting.
With this basic framework in place, OSP can be used to analyze sky glow, by measuring the overall average illuminance on the side and top planes of the box; light trespass, by calculating the maximum illuminance on any of the side planes; and glare, by computing three illuminance values obtained at the property line, according to Rea.
In order to provide insights into the values of glow, trespass, and glare produced by nighttime lighting, Rea and LRC scientists Jennifer Brons and John Bullough worked with application engineers to study 125 lighting designs for four common nighttime lighting applications car parking lots, roadways, sports fields, and plazas.
"Project participants used OSP with their preferred lighting calculation software programs, documenting the area of each side of the box, average illuminance on each side of the box, and the maximum illuminance on the vertical sides of the box," said Brons. "The measurements were then used to calculate the three aspects of light pollution. These empirical results are the first ever published that we know of showing how much light leaves a sample of outdoor lighting installations, measured in terms of glow and trespass. Once application engineers had these data they began to find creative solutions to reduce light polluti
|Contact: Amber Cleveland|
Rensselaer Polytechnic Institute