The same level of lighting in the same room can consume tens of times more energy, depending on the type of bulb used. This is one of the clearest examples that "working" is not the same as "efficient."
How do we fairly compare bulbs?
The correct measure for comparison isn't power in watts alone (since less wattage for the same light output is the goal), but rather luminous efficiency — the amount of light produced (measured in lumens) per watt consumed. Two bulbs with similar brightness (the same lumen count) can consume very different amounts of power depending on the technology.
Comparison of common types
| Type | Relative Efficiency | Approximate Lifespan | Note |
|---|---|---|---|
| Incandescent | Very low | ~1,000 hours | Most energy converts to heat, not light |
| Halogen | Low | ~2,000-4,000 hours | Slightly better than incandescent, high heat |
| Compact Fluorescent (CFL) | Medium-high | ~8,000-10,000 hours | Needs time to reach full brightness |
| LED | Very high | ~15,000-50,000 hours | Instant brightness, relatively low heat |
Why has LED become the default choice?
In addition to high energy efficiency, LED has a lifespan many times longer than incandescent or halogen bulbs, produces less heat (which reduces the air conditioning load in indoor rooms during summer), and unlike some older types (such as fluorescent), doesn't contain materials requiring special disposal. The higher initial cost of an LED bulb is generally offset quickly through savings on the electricity bill and less frequent purchasing.
Replacing a 60-watt incandescent bulb with an LED bulb at the same light level might use only about 8-10 watts — a savings exceeding 80% of that point's consumption. To see how this difference translates into money on your bill, see How to Calculate the Monthly Running Cost of a Specific Appliance.
Sample answer: The correct measure is luminous efficiency: the amount of light produced (in lumens) per watt consumed. Two bulbs with similar brightness (the same lumen count) can consume very different amounts of power — for example, an LED bulb might give the same light as a 60-watt incandescent bulb while consuming only 8-10 watts, a huge efficiency difference despite similar apparent brightness.
Choosing a bulb based on power in watts alone, assuming that "more watts always means more light" in a fixed way across different types. This relationship only holds within the same type; when comparing different types (LED versus incandescent, for example), you should rely on the lumen value (actual light output) listed on the package, not the wattage.
Want to master home electrical wiring and installations?
Follow trainer Fahad Refai's Electrical Wiring & Safety courses — practical, step-by-step guidance from the basics to safely installing distribution boards and protection devices.
Browse Fahad Refai's Courses