Reducing light pollution

Michael Siminovitch, a director of UC Davis' California Lighting Technology Center, and his colleagues have developed a novel system that uses about 20 per cent of the energy of conventional parking lighting systems while reducing light pollution.

The system, unveiled this month in a UC Davis parking garage after two years of development and field testing, is a highly efficient and innovative package of technologies.

The system includes light-emitting diode (LED) lights that give off bright white light but use little electricity.

Each lighting fixture - called a luminaire - has three light bars containing 60 LEDs.

Compared to conventional metal-halide lights, LED lights use less power (85W versus 175W), last longer and contain no mercury.

The system also includes motion sensors that detect the motion of a person or vehicle within about 35ft.

When no motion is detected for a designated period of time (30 seconds to 30 minutes), the sensor switches the LED light from a high level to a low level that uses half the energy.