Oxford study proves heat pumps triumph over fossil fuels in the cold::Published Monday in the scientific journal Joule, the research found that heat pumps are two to three times more efficient than their oil and gas counterparts, specifically in temperatures ranging from 10 C to -20 C.
If you are comparing gas to heat pump efficiency, it is more like 85-90% vs 350-500% efficiency.
Because in the gas furnace efficiency they only calculate the efficiency of burning gas but miss to include the auxiliary electricity that is needed to run the system.
In a heat pump system everything (running fans etc.) is included in the efficiency calculation. The efficiency itself is depending on the source of the heat pump. In a really harsh climate a ground / geo thermal source might make sense. But usually the average temperature is higher than you might think.
And for the environmental effect: modern gas power plants run at 50-60% efficiency so with a heat pump you are always burning less gas even if the gas plant is less efficient then the gas furnace.
It would be interesting to know what extreme cold means.
That’s a good point about the furnace fan!
I’m using what the study calls extreme cold, which would account for about 3 months of the heating season where I live, and that’s where I got the lower efficiency numbers from too as they state the COP is around 2.75 (roughly 3 months of the year here) in the “mild cold” and only around 2 at best in the colder months.
We have a bit of an unusual climate here with fewer people so most of the info I find tends to focus on where more people live and the climate is different so it’s tough to figure out. There’s a good three months where no heating is required at all (and increasingly, ac units are in demand). A couple of years ago we had close to an 85°C temperature swing from the end of February to mid June!
Natural gas is plentiful and cheap so it’s used for central heat and hot water here, sometimes clothing dryers too but that’s less common. I still end up paying a gas bill in the summer months essentially just for admin fees and such, so the temptation is to go fully electric (would have to change the HWH) with a heat pump system and resistive backup heat. The problem is from what I can tell, the additional cost isn’t quite worth it yet (the system might not even save any money and is more expensive to install/maintain), and the emissions difference is tough to calculate when a third of the power comes from coal and over half from natural gas…
You’re right to be concerned about emissions, if you live in a place where a significant portion electricity comes from coal its almost certainly cleaner to just burn the natural gas. Which area of the world is this if you don’t mind saying?
I’m in Alberta (Canada)
Haha yeah that would do it. Even here in Ontario we still have a lot of houses with gas hookups despite our clean and (relatively) cheap electricity, but I see more ads for heat pump installs now so it’s definitely changing.