The way modern heat pumps work, I can't answer your question yet. What's the outside temperature? Let's say that taking your room from 15C to 20C takes 1.0 ener

The way modern heat pumps work, I can't answer your question yet. What's the outside temperature? Let's say that taking your room from 15C to 20C takes 1.0 energy unit. If it's 15C outside, then I can use a heat pump to gain a bunch of efficiency, say only using 0.2 units of electricity to heat up the inside by one unit. If it's 25C outside, I can do the same in reverse, but I do have to also cool the A/C. We'll say taking the room from 25C to 20C when it's 25C outside takes 0.25 units. The problem happens when there is a big difference in outside temperature. All of the gains of heat pumps disappear. So cooling from 25C inside to 20C inside when it's 30C outside might take 0.5 units of energy, which is a pretty common case. Heaters generally have to deal with much bigger swings, though. It's not uncommon to heat from 15C inside to 20C inside while the outside is at -10C, which takes (asymptotically approaching) 1.0 energy unit. So the inefficiency of the A/C producing heat does matter, but not as much as the difference between the desired temperature and the outside temperature. The rate of heat transfer of the house also depends on the difference in temperature. Keeping a house 10C cooler than ambient takes less energy than keeping a house 20C hotter than ambient. Considering that temperatures on Earth vary from about -90C to 50C, and humans like to keep indoor temps around 20C, cooling is generally more efficient than heating.