Studies suggest that a complete conversion to the lights could decrease carbon dioxide emissions from electric power use for lighting by up to 50 percent in just over 20 years; in the United States, lighting accounts for about 6 percent of all energy use. A recent report by McKinsey & Company cited conversion to LED lighting as potentially the most cost effective of a number of simple approaches to tackling global warming using existing technology.
LED lighting was once relegated to basketball scoreboards, cellphone consoles, traffic lights and colored Christmas lights. But as a result of rapid developments in the technology, it is now poised to become common on streets and in buildings, as well as in homes and offices. Some American cities, including Ann Arbor, Mich., and Raleigh, N.C., are using the lights to illuminate streets and parking garages, and dozens more are exploring the technology. And the lighting now adorns the conference rooms and bars of some Renaissance hotels, a corridor in the Pentagon and a new green building at Stanford.
LEDs are more than twice as efficient as compact fluorescent bulbs, currently the standard for greener lighting. Unlike compact fluorescents, LEDs turn on quickly and are compatible with dimmer switches. And while fluorescent bulbs contain mercury, which requires special disposal, LED bulbs contain no toxic elements, and last so long that disposal is not much of an issue.
Another issue is that current LEDs generally provide only “directional light” rather than a 360-degree glow, meaning they are better suited to downward facing streetlights and ceiling lights than to many lamp-type settings.
And in the rush to make cheaper LED lights, poorly made products could erase the technology’s natural advantage, experts warn. LEDs are tiny sandwiches of two different materials that release light as electrons jump from one to the other. The lights must be carefully designed so heat does not damage them, reducing their lifespan to months from decades. And technological advances that receive rave reviews in a university laboratory may not perform as well when mass produced for the real world.
The lights are also rapidly moving indoors, where they could have an enormous effect on climate change. About 20 percent of carbon dioxide emissions associated with buildings in the United States and the United Kingdom are related to indoor lighting; in some houses the number is as high as 40 percent.
This month, LED lights were for the first time the centerpiece at two of the world’s major trade shows for lighting, Lightfare International in New York and EuroLuce in Milan. A growing number of builders are starting to fit them into public buildings, offices and homes.