LED vs halogen vs CFL

The first two rows decide the argument for almost everybody. An LED producing the same light as a halogen draws a fraction of the power and lasts roughly ten times as long, and the U.S. Department of Energy's life-cycle assessment put LED and CFL life-cycle energy at around a quarter of incandescent for the same delivered light.

The EIA has tracked LED efficiency and quality improving steadily over the last decade, which is the reason the honest answer to this comparison has changed. Ten years ago the light-quality objections to LED were substantial. Most of them have since been engineered away.

What that means in money is on what does an LED bulb cost to run, which works the arithmetic through at an illustrative rate.

Dimming down to a glow. A halogen filament dims by getting cooler, so it goes warmer and softer as it goes down and reaches genuine candle levels smoothly. An LED dims electronically, and cheap combinations of bulb and dimmer drop out, flicker, or stop dead at 20%. This is the objection with real substance, and it is a compatibility problem rather than a technology one - the fix is in why do my dimmable LEDs flicker and leading edge vs trailing edge dimmers.

Color rendering. Halogen is a continuous-spectrum source and renders color essentially perfectly. That used to be a decisive advantage. It is now a narrow one, because a CRI 95 LED is widely available at ordinary prices, and 95 is good enough that the difference is invisible outside color-critical work. If you buy on CRI rather than on price, the objection largely disappears - the argument is in best high-CRI LED bulbs.

CFL has no equivalent argument in its favor. It warms up slowly, it dislikes being switched frequently, it dims badly if at all, and it contains mercury. It was a transitional technology and the transition is over.

Replace halogen that runs for hours. Downlights, kitchen fittings, a lamp you use every evening - the efficiency gap is large enough that this pays for itself in a way most efficiency advice does not. A 1,500 lumen CRI 95 bulb replaces a bright halogen without losing anything you would notice.

Replace CFL as it fails. There is no reason to buy another one, and no reason to rush a working one into the bin either. When it goes, an LED of the same output is better on every axis.

Buy on the published numbers, not the equivalence claim. "60W equivalent" is a marketing shorthand that different manufacturers apply differently. The lumen figure is the specification - 800 lm is a 60W-ish bulb and 1,500 lm is a 100W-ish one, regardless of what the front of the box says.

Match the rating to the fitting. The one place LED reliably underperforms its rated life is a sealed fixture, because heat is what kills the driver. Use an enclosed-rated bulb in anything sealed and the 25,000 hour figure becomes plausible again.