Change A Light Day

What the day is

Change a Light Day is observed on October 4. The idea is deliberately small: replace one inefficient bulb, on the reasoning that a single easy action repeated across millions of households adds up, and that people who make one change often make more.

It falls as the northern hemisphere moves into the dark half of the year, when household lighting use climbs sharply.

Origin and background

The day grew out of the Change a Light, Change the World campaign run under the ENERGY STAR program, a joint effort of the US Environmental Protection Agency and Department of Energy. The campaign asked households to pledge bulb swaps and ran through the 2000s, when compact fluorescent lamps were the efficient option being promoted.

The technology moved on quickly. CFLs were a large improvement on incandescent bulbs but had real drawbacks: slow warm-up, poor color, and mercury content that complicated disposal. LEDs solved all three and then kept improving. A modern LED uses roughly a fifth to a quarter of the energy of the incandescent bulb it replaces, lasts many times longer, and comes in a range of color temperatures.

Falling prices and efficiency standards have done most of the work since. In much of the world the inefficient bulbs the campaign targeted are no longer manufactured, which makes the day partly a historical marker. It still has a point, though, because plenty of homes have halogen fittings, old CFLs and forgotten fixtures that were never changed.

How to take part

• Start with the lights you use most. A bulb burning four hours a day is worth changing; one in a closet is not.
• Shop by lumens, not watts. Roughly 800 lumens replaces an old 60-watt bulb.
• Pick the color temperature deliberately. Around 2700K is warm and suits living rooms; 4000K and above reads as cold indoors.
• Check for dimmable if the fitting has a dimmer. A non-dimmable LED on a dimmer circuit flickers and fails early.
• Recycle old CFLs properly rather than binning them, because of the mercury.