To change the bulbs in the 60-foot-high ceiling lights of Buckingham Palace’s grand stairwell, workers had to erect scaffolding and cover precious portraits of royal forebears.

So when a lighting designer two years ago proposed installing light emitting diodes or LEDs, an emerging lighting technology, the royal family readily assented. The new lights, the designer said, would last more than 22 years and enormously reduce energy consumption and carbon dioxide emissions  a big plus for Prince Charles, an ardent environmentalist. Since then, the palace has installed the lighting in chandeliers and on the exterior, where illuminating the entire facade uses less electricity than running an electric teakettle.

In shifting to LED lighting, the palace is part of a small but fast-growing trend that is redefining the century-old conception of lighting, replacing energy-wasting disposable bulbs with efficient fixtures that are often semi-permanent, like those used in plumbing.

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.