In Tenderloin district of San Francisco, U.S., the city government has installed "smart" LED (light-emitting diode) street lights, which is part of a wide effort by the city to cut spending and reduce energy use.

The LED panels are connected to servers over existing power lines, from which the city manages the operation of the LEDs. Based on data retrieved from the panels, management consoles can remotely turn off or dim lights depending on time, weather and traffic.

"We have installed 50 panels in the Tenderloin district as a demonstration," said Tony Winnicker, a spokesman for the San Francisco Public Utilities Commission. "It's an area where reliable street lights are important for public safety. They last longer, and it's brighter at street level," he said.

The energy savings will help the city reduce greenhouse gas emissions by 2012 to the levels of 1990, he said. Shutting down individual or a group of lamps on a situational basis -- like time of day -- also prolongs life of LEDs. In the long term, that will cut greenhouse gas emissions and reduce lamp acquisition costs.

The city is also equipping panels with traffic and weather sensors to determine LED behavior. For example, lamps could stay on during a rainstorm based on data gathered by weather sensors. The sensors also provide fringe benefits like the ability to flash lights for first responders to quickly locate emergency scenes.

Additional savings come through remote management of the street lights. The management console is also available as a Web service, so street lights could be managed over the Internet using mobile devices like the iPhone, said Steve Nguyen, director of corporate marketing at Echelon.

Many cities -- especially in Europe -- are taking a phased approach in implementing smart street lamps, Nguyen said. Cities usually don't want to put all their eggs in a single basket, so they break up implementations over multiple vendors.

The need to cut costs may seem crucial during the recession, but San Francisco is taking a phased approach in LED deployment. Winnicker said the technology needs to be fully evaluated before implementation. A heavy up-front cost is also involved in deploying the new technology, so it may be appropriate for the city to take a gradual approach.