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Comment by Scoundreller | Hacker News Reader

> Isn’t this expensive to run? It draws about 2 kWh per day (assuming 8h of usage), which costs about $0.30 at typical rates. This is comparable to one day of a modern fridge or one load of laundry. Power is cheap, folks!

But it will offset your other heat sources.

If you live alone, you can treat it like a room heater and lower the temperature for the rest of your home.

Since the bulb is radiating heat some degree of heat, you may be able to keep the temperature of the room you’re in lower without feeling cooler.

The fan is a bummer though.

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2 kWh is kind of nuts. Yes, it's in the same order of magnitude than the fridge and washing machine, but those already tend to be the largest consumers of electricity in a household, unless you're doing cooling or heating with electrity. And a modern fridge suitable for 2 to 3 persons will be more like 0.5 kWh per day and a load of laundry is < 1 kWh.

Three standard 60 W incandescent bulbs will draw just under 2 kWh in 10 hours, and not too long ago it was completely normal to have many more of these on at the same time.

And if you're trying to light your whole house this way you may need three or four of these bulbs. I guess you'd just keep whichever is in the room you're in on though.

While LEDs do produce some waste heat, efficient ones convert 50%+ of the input power to visible light, so it's less than you might think (compare to ~10% for incandescents, iirc). The bulb I have doesn't have a perceptible effect on my room temperature (although I guess it probably does cause the thermostat to turn on a tiny bit less often).

That visible light is still mostly ending up as heat in your home though, other than what spills out of windows.

Can you give an example of an LED bulb installation with 50%+ luminous efficacy? Perhaps you are thinking of the raw lumens/watt coming out of lab-grade LED material without considering other system draws (cooling, power conversion)?

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