It's not just the waste heat. If you're well positioned, the radiant heat off an incandescent can heat a human body very effectively. Remember the "heat lamps

It's not just the waste heat. If you're well positioned, the radiant heat off an incandescent can heat a human body very effectively. Remember the "heat lamps" some bathrooms used to have? The same effect is found in regular lighting incandescents, especially if you're directly below an overhead fixture. "Radiant heating of humans" is rather substantially more efficient, in terms of "human happiness per watt used," than heating the entire house. I've got some radiant heat panels that get used heavily in the winter, and there's nothing like a good radiant kerosene heater (mine is 10k BTU, about 3kW, almost entirely as heat) on a cold winter night.