[thatcherc]

That 100% efficient figure is correct - you get one Watt of heat for one Watt of electricity. It's just that heat pumps can deliver 3 or 4 Watts of heat for each Watt of electricity (usually quoted at around 300% or 400% efficiency!). Compared to that, resistance heaters aren't as efficient.

The explanation that made the most intuitive sense to me is that it takes less energy to move heat from one place to another (air at 273 Kelvin to air at 300 Kelvin, like a heat pump does) than it does to create heat from nothing (like a resistor does). That's why the heat pumps can get deliver more heat to you from the same amount of electricity.

[haberman]

That makes sense, but GP was calling resistive heating inefficient compared with propane or wood heat, which doesn't make sense to me.

[bluGill]

The best natural gas power plants are 64% efficient. A modern furnace is around 95%. Sure electric restive heat is 100% efficient in your house, but the whole system us much worse.

Of course electric can come from many sources, if your is renewable at the time resistive is good. However you might also be using some old 1920s coal generator that is 10% efficient (these still exist, but are only used in the worst emergencies)

[anikom15]

Natural gas (not sure about wood; in most areas it’s abundant) is about 1/3 of the cost of electricity in America, so it’s economically less efficient.