Comment by szvsw

A lot of what you said is intuitively/directionally correct, but misses a lot of important physics related to heat transfer in buildings and operational questions of space heating equipment.

This is your most accurate/relevant point:

> All of this is ignoring the fact that it’s easy to create a tiny personal heated environment around an individual (it’s called a woolly jumper).

Whereas this is plainly wrong:

> It’s much easier, and consumes less additional energy, to heat an occupied space, than to cool it.

And then the following is correct but the marginal reduction in load is minimal except in relatively crowded spaces (or spaces with very high equipment power densities):

> Thanks to the fact that your average human produces 80W of heat just to stay alive.

The truth is it is generally easier to cool not heat when you take into account the necessary energy input to achieve the desired action on the psychrometric chart, assuming by “ease” you mean energy (or emissions) used, given that you are operating over a large volume of air - which does align with your point about the jumper to be fair!

Generally speaking, an A/C uses approx. 1 unit of electricity for every 3 units of cooling that it produces since it uses heat transfer rather than heat generation (simplified ELI5). It is only spending energy to move heat, not make it. On the other hand, a boiler or furnace or resistance heat system generally uses around 1 unit of input energy for every 0.8-0.9 units of heating energy produced. Heat pumps achieve similar to coefficients of performance as A/Cs, because they are effectively just A/Cs operating in reverse.

Your point about a jumper is great, but there are local cooling strategies as well (tho not as effective), eg using a fan or an adiabatic cooling device (eg a mister in a hot dry climate).

> So cooling a living space is always more costly than heating a living space.

Once you move to cost, it now also depends on your fuel prices, not just your demand and system type. For instance, in America, nat gas is so cheap, that even with its inefficiencies relative to a heat pump, if electricity is expensive heating might still be cheaper than cooling per unit of thermal demand (this is true for instance in MA, since electricity is often 3x the price of NG). On the other hand, if elec is less than 3x the cost of nat gas, then cooling is probably cheaper than heating per unit of demand, assuming you use natural gas for your heating system.