The Incredible Shrinking Energy Use of a Light Bulb
Thanks to rapid gains in efficiency, home lighting accounts for a much smaller share of the world’s power consumption than it used to.
A worker demonstrates various LED light bulbs.
Photographer: Udit Kulshrestha/BloombergLast month, new lighting energy efficiency rules took hold in the US, requiring new light fixtures to provide at least 45 lumens per watt of electrical input. While that does not ban incandescent bulbs per se, it has set a standard that is effectively impossible for them to meet. It also puts paid to the familiar illumination device dating back to Thomas Edison.
The new rule is not as dramatic as it might sound — 45 lumens per watt is actually well below the efficiency of light-emitting diodes. LEDs are about nine times more efficient than old incandescent bulbs. Forty-seven percent of US homes use mostly or only LED illumination already. It wasn’t the case just a decade ago, but consumers in the US are now tilting toward LEDs and away from every other light source.