Comment by jfengel
9 hours ago
I'm surprised that cooling takes less energy than heating. I imagine that depends a lot on the temperature range; they only need so much to cool a room even on a "hot" day in the UK.
Still... AC still feels like magic. I know how it works and understand the over-unity factor. But it feels like it ought to take enormous energy for it to work at all.
I think specifically it's comparing gas heating vs AC. Heat pump heating would probably do better. In other words, it takes less energy to move heat inside/outside than to "create" it
(With caveats like heat pumps are much less effective in extreme cold)
You can select gas heating vs electric heat pump. The heat pump looks to be about a third the cost of gas.
Yeah without knowing the climate, temperature delta and insulation these values don't really mean much.
You can reject 4 watts of heat with 1 watt of electricity using vapor-compression refrigeration.
You can get that up to 7 or 8 watts (or more!) per watt with evaporative cooling towers and vapor-compression combined.
AFAIK you can’t move heat into somewhere using cooling towers, they only increase cooling efficiency.
Heat pump heating is limited to around 4W of heat moved for every 1W of electricity, with the efficiency dropping as delta T drops (aka as it gets colder outside)
You can generate 1 watt of heat with 1 watt of electricity and a resistive heater, they’re more or less 100% efficient.