What is the correct order of lightbulbs from most to least energy-efficient?

• A. LED, CFL, Halogen, Incandescent
• B. Incandescent, Halogen, CFL, LED
• C. CFL, LED, Halogen, Incandescent
• D. Halogen, Incandescent, CFL, LED

Answer: (A)

Energy efficiency means how much light you get for the electricity you use, usually measured as lumens per watt. LEDs are the most energy-efficient because they convert electricity into light with very little waste as heat. CFLs also use electricity more efficiently than traditional bulbs by producing light through fluorescence, so they’re less efficient than LEDs but more than incandescent or halogen. Halogen bulbs are a step up from standard incandescent bulbs but still waste a lot of energy as heat, making them less efficient than CFLs and LEDs. Traditional incandescent bulbs are the least efficient because most of their energy ends up as heat rather than light. So the order from most to least energy-efficient is LED, CFL, Halogen, Incandescent.