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.
WELL FUCKING OBVI-
Oh right, I forgot some people are really pulling for this fossil fuel think to pull through.
create energy
Ummm… that’s not how it works.
They actually added a correction at the end for that
Maybe someone can help me answer this question as I’ll be replacing my old furnace in the near future and am curious about the heat pump systems.
Studies like this are only looking at efficiency and not total energy usage or heating capacity so how do you compare apples to apples? A high efficiency forced-air furnace using natural gas is something like 95% efficient, and a heat pump can be something like 150%-200% (because you’re moving the heat instead of creating it), but the total output capacity matters as well as the efficiency of generating and transmitting the electricity. Also, I don’t think the power needed to run the fans gets factored in from what I can tell and I expect a heat pump system to need fans running far more often and for longer. Since heat is constantly being lost to outside then whichever can work faster might have an advantage keeping ahead of that entropy too…
I’m living in a climate considered “extreme cold” in this study btw. Best I’ve been able to figure out, a gas furnace is still much cheaper to install/operate (it’s pretty cheap here) but is also still be better for the environment as my electricity tends to be generated primarily from natural gas and coal (at an efficiency lower than a natural gas furnace does).
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!
This commentary focuses on the performance of air-source heat pumps in mild European winters with average January temperatures above −10°C. We refer to these heating conditions as “mild cold climates”, whereas those with average temperatures below −10°C in the coldest month are designated “extreme cold climates”.
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.
I don’t know that we really needed a study for this. You can find the COP vs temp vs capacity curves for every heat pump out there. This will tell you exactly how many BTUs of heat the pump will produce given a watt of electricity input. I guess they were just validating that the curves were accurate?
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People think that’s a killer argument against heat pumps when it absolutely isn’t.
In that sort of climate you get a hybrid system or just leave your old furnace in as backup. You’ll use the furnace for the couple of days/weeks when it is below -25c/-13f and use the heat pump for the 6 months around that time window and save huge amounts of energy because you only use the heat pump when it’s most efficient. A hybrid system will improve efficiency because it combines the technologies at transition temps while just keeping the old furnace as backup is obviously much cheaper, since you can also get a smaller unit than you normally would because you don’t have to worry about the coldest period.
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Okay, I suppose you wouldn’t do that when replacing and old furnace but rather go for a hybrid system. In Europe loads of people are reacting to hiked gas prices and have perfectly fine furnaces in place that they don’t want to get rid of.
You might not be totally out of luck:
- More modern units do pretty well down to -20f.
- Ground-source systems don’t care about air temps (but are more expensive)
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I don’t think Siberia counts as a place where people want to live.
Yowsa! That’s cold.
That said, ground-source systems have been used to good effect in climates like that! But, of course, do what’s right for you 🙂
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Which is the absolute minority on that regard, most people live in climates where it doesn’t get that cold.
it doesn’t get that cold.
For now.
I’d also add that like, for a lot of Scandinavia heat pumps work just fine? Like does America just have some really bad heat pumps or something?
I think the only reason why you wouldn’t install one here (aside from obvious cost issues) would be if you already have a robust heating system built into your home, like a hot water system. And if that’s the case, you can use the heatpump of the earth - geothermal! Use the power of the earth’s molten core to heat and cool your home!
(… geothermal isn’t as ubiquitous as I make it sound it’s just, really fucking cool)
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1.25% of population. The minority point stands
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Like consistently? Or just one or two days a year? Because I feel like bringing out the electric heaters a few times a year is way better than just giving up and using fossil fuel all the time
Also I’d mention that heat pumps are super common over here in Scandinavia so I have my doubts that it’s an issue with the medium and not something else. Maybe you guys have like, heat pumps that are more designed for the heat rather than the cold?
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Not in January in Central New Hampshire.
They work in Sweden… and Canada…
Sure it does. Unless your average temp in January is under 5F? And on those really cold days the gas furnace kicks in anyway, so you get the most efficient heating no matter what.
So you still need a gas furnace…
A/C guy who’s the son of an A/C guy here. Heat pumps lose efficiency the colder it gets. I wouldn’t bother with one if you’re in a northern climate. Lower midwest, you might be able to save money with a heat pump over natural gas, but it will depend heavily on the cost of the respective energy. For me, in the central US, we have great prices on gas and somewhat crappy prices on electricity (vs most surrounding regions) and it’s definitely cheaper for me to stick with gas heat.
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Your information is outdated. It is even clearly mentioned in the one-sentence summary in the OP:
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.
This is the correct take for a conventional heat pump. However, there are relatively new geothermal heat pumps that can heat down to -30°C (-22°F) and are much more efficient.
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Thankfully heat pumps have gotten better since your father’s day. And natural gas is only going to keep getting more expensive. For a price of equipment that will last you 15-25 years it’s becoming harder to justify gas heating.
For new builds ground source heat pumps should become more standard, they cost more, but they’ll save a lot in the long run.
But its all irrelevant because the most effective way to keep warm is to continue with global warming. Soon we wont have a cold season to worry about. 😜
I know you’re joking but the reality is we’ll probably get worse cold weather alongside the warmer weather - the weather will be more extreme at either end.
Scary, isn’t it?
Yet there are still people out there denying it.
If you’re on propane, it’s more likely to be cheaper. Particularly over the course of an entire heating season, because they’re more efficient in fall and spring than the coldest part of winter.
But yeah, this study wasn’t looking at cost per therm but just raw COP, which is a pointless metric. It doesn’t even compare the number of watts of heat from burning natural gas in a furnace vs in a modern power plant that supplies a heat pump. Although since we don’t have a carbon tax, that’s only a theoretically interesting comparison.
Heat pumps work fine for most people in the north. Mitsubishi’s cold climate heat pumps supply 85% of their rated heat at -13F. Buffalo is a city known for its winters, and the last time Buffalo’s lowest temperature was below that was 1982. They’re just going to be a more expensive option for most people right now.
My father in law went to a heat pump instead of propane this year. No natural gas where he lives.
But he also dropped 20k on a solar system to power it.
How long would the return on cost savings take for it to pay itself off?
Ditto. At least with gas I’m not paying Alabama Power’s rates.
If you posted that earlier today you would have gotten a spanking for saying anything critical about heat pumps. Or people just don’t like me in particular. Hard to tell.
