- cross-posted to:
- technews@radiation.party
- cross-posted to:
- technews@radiation.party
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.
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The Oxford study is really good. But I can’t say the same about this article.
A COP of ~2 is not great for a heat pump, calling this a triumph is really weird. But from a journalist saying that a COP above 1 means the heat pump “creates energy”, I am not sure I should have expected more.
But what’s great is that this COP of 2, while bad, is not catastrophic. That’s still in territory where gas boiler are more cost efficient that a heat pump, but unless you are living in a place that is consistently under -10C for several months, then a heat pump has lower running costs than a gas boiler. And you are starting to hit pretty northern territories with this.
What’s important is also to be able to store heat during the day so that the heat pump runs at its most efficient time. But that can unfortunately coincide with the higher consumption time, so the timing needs to be adjusted properly to avoid using it during consumption peaks.
a journalist saying that a COP above 1 means the heat pump “creates energy”
But what’s great is that this COP of 2, while bad, is not catastrophic. That’s still in territory where gas boilers are more cost efficient that a heat pump, but unless you are living in a place that is consistently under -10C for several months, then a heat pump has overall lower running costs than a gas boiler. And you are starting to hit pretty northern territories with this.
I actually have a hybrid furnace/heat pump system, and I live in southern Ontario, Canada. The furnace is the auxiliary heat source and it only kicks in when the outdoor temp is below -6C. I’ve only had this system through one winter so far, but I think I could count the number of days the furnace ran without running out of fingers. My electricity bill went up some of course, but my winter gas bill went down a lot.
Edit to add: I wasn’t shopping for a hybrid system in particular, but I got this upgrade through the Canada Greener Homes Grant and there were limitations on which units qualified for rebates. For my install (forced-air with existing duct-work), the hybrid systems were the ones that qualified.
Was there any specifig brand/seer rating restriction with the GHGrant? I just applied and will be going this route, but I don’t want to be paying $15000 for a specific brand or something if I can get similiar equipment that might not be on a list.
Was there any specifig brand/seer rating restriction with the GHGrant?
It’s more complicated than that. The major components of the system all have to be qualified for the rebate, down to the component model numbers. There’s a lookup tool to see which model numbers qualify. For a hybrid setup like mine, there are three parts:
- Outside model number: this is the actual heat pump component that gets installed outside
- Inside model number: this is the condenser coil that gets installed on top of the furnace
- Furnace model number: this is the model number of the furnace itself
A ductless system would only have two part numbers involved, the outside heat pump unit and the inside wall unit (though a ductless install can have multiple inside units in multiple rooms). No furnace for a ductless system of course.
Every HVAC company I talked to was pretty knowledgeable about the GH program, so if you tell them you’re an applicant then they should put together a quote that qualifies. Multiple HVAC reps advised me to make sure that all rebate-covered part numbers were listed clearly on the invoice. Apparently if that info is missing it can derail the rebate until the invoice is updated with full info.
That’s a useful tool, thanks for linking that. How much did your hybrid system end up costing?
The total install was $12k. I also did another 1k in retrofits under the Greener Homes program, but I did the Greener Homes loan as well. I had to outlay the $13k up front, but then I got all of that back in a 10-year, 0% interest loan, plus $5600 in rebates on top ($5k for the heat pump, $600 for the furnace). The loan processing company debits my account $110 a month, which is low enough that it doesn’t really sting.
I debated doing solar as well, since the Greener Homes loan goes up to $40k. Solar would gave easily soaked up the remaining $25k available in the loan. My roof isn’t ideal for solar though, and I didn’t want to triple the loan’s monthly payments for a solar install that wouldn’t have paid for itself over time.
TY. I’m considering solar as I picked up 2 pallets of panels for our farm, and I don’t need all of them there. I assume there’s all sort of permit issues in the city for that though, so I might just skip it.
Even the study could have used some better clarification on geothermal HVACs, which is the direction we should all be heading towards:
Ground-source heat pumps typically provide a very high level of efficiency, even during cold weather. The reason is that soil temperature does not change significantly between seasons, resulting in a higher—and more constan—COP. In addition, ground-source heat pumps do not need to expend energy on defrosting.
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”.
No, why?! Gimme the COP on geothermal. Google tells me it’s 3 to 5, but I would have liked a better source.
Regardless, while I understand that we should spread out our solutions, I don’t understand why we’re not talking more about geothermal HVAC systems. Household solar is all the rage, but my gas company is still charging me $25 a month just to have the gas on, never mind the winter costs.
If we’re talking about $5K a hole to dig for geothermal, that seems like a hell of a lot more cost-effective solution than either gas-based HVACs, or these air-based heat pumps. If it’s an area with only mild winters, you probably only need the one hole, which will last for 100 years at least. At most, we’re talking about 3-4 holes for a large house in Canada, and that’s going to pay for itself in 10-15 years.
Geothermal has advantages, but air source is getting so good that it’s really becoming a niche.
Spending $5K on insulation or heat recovery ventilation will be more effective than spending it on a hole.
I saw an awesome home refurbishment in Montreal, they just went all-in on insulation. The heating was just done with a 500W resistive heating coil, just for the coldest days. They didn’t even have a heat pump, except for the heat pump boiler. The heat recovery ventilation did the rest.
What is HRV? I thought it meant a ground loop heat exchanger. I’ve heard about it in the passivhaus model but don’t understand it.
Houses need fresh air and need to expel dirty air.
The dirty air is warm, while the outside fresh air is cold. With heat recovery ventilation, the heat is transferred into the incoming air and the exhaust air becomes cold. This warms up the air in a very efficient manner.
It can also be combined with a heat pump to extract even more heat out of the exhaust.
What if you already have good insulation? It’s already well-known that old houses have shit insulation, so of course it’s worth investing money into that if you already need it. But, even heating a new house can be expensive.
If you have good insulation then the weakest link is usually heat lost through ventilation, or an inefficient heating system.
Ground source heat pumps have their place, but it’s really a niche. It is possible to cheaply heat a home without them.
That’s still in territory where gas boilers are more cost efficient that a heat pump… a heat pump has overall lower running costs than a gas boiler
You just contradicted yourself… what did you mean here?
Electricity is 3x the cost of gas, so unless the heat pump has the COP of 3 or above it is more expensive to run. Once you factor in the high cost of installation people aren’t installing these things to save money.
It’s not a contradiction if you put my whole sentence. When it is really cold, a heat pump will be more expensive than a gas boiler. But over a full winter (hence “overall”), the period where it is more efficient make up for it, especially since that when it is bad, it is not that bad.
But you are right to mention the high cost of heat pumps. I would not advise anyone to get a heat pump with a goal of saving money, the return on investment is slow and rather small.
I don’t agree with generalizing that ROI is slow and small. There are too many variables here specific to each market, location, and home. Someone with an old propane or oil boiler that is already planning to buy a new AC will absolutely see massive ROI going with a heat pump. In the US, federal standards will make furnaces more expensive (condensing only soon) and heat pump costs can be heavily subsidized. I bought a new HP that was cheaper than my neighbors new AC/furnace after incentives, and my running costs will be lower.
Heat pumps are A/C in reverse. It makes total sense instead of using fire to heat air.
WELL FUCKING OBVI-
Oh right, I forgot some people are really pulling for this fossil fuel think to pull through.
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).
Under the conditions you describe, a hybrid setup will work best.
In a hybrid setup, the heat pump is providing most heat when it isn’t very cold, while the traditional heat source is providing heat on really cold days.
A few years ago, the temperature where the system would switch was 5 C. Nowadays it’s more like -10 C. As heat pumps get better, hybrid loses territory, so you could also just wait a few years and then switch.
Hybrid gives best of both worlds at the cost of added complexity.
If you have A/C then the cheap way to do hybrid is to keep the traditional heating system but use the A/C in heating mode on mild days.
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)
For sure look into any subsidies available to you and see if they make a dual fuel system feasible. In your situation if you buy a high efficiency furnace, it may never make economic sense to run the heat pump, but things could always change and it’s a simple enough task to find your break even (economic balance) point when fuel prices change. My current break even point is well beyond the temperature you would consider running heat, but I still run my heat pump in the shoulder seasons to exercise it.
They’re only two to three times more efficient if they aren’t frozen solid. Don’t know how it works in Canada, but my mini-split heat pump can’t handle a week of 10F let alone -20 C - sure it will put out some heat, but it absolutely needs to be supplemented with my wood stove. And I live in the South. Maybe there’s some new high tech heat pumps that cost a fortune and don’t freeze over in the insane temps of the great white north? EDIT: some idiot downvotes me when I make an open-ended comment with no position stated at all. lol.
Your mini-split isn’t designed to function as a heat pump at low temperature.
In places like Sweden, they also use heatpumps that are designed for those conditions.
In other news, don’t drive in a Swedish winter with summer tires.
Excellent. Now I know that there are different classes of heat pump. Mine is not for prolonged crazy-low temps, others are. Thank you.
Indeed, but yours is probably cheaper and more effective at cooling when it’s hot and humid out.
For people up north, they will buy a “cold climate air source heat pump”. In temperate regions, an “air source heat pump” will suffice, while down south you will buy an “A/C with a heating mode” (also called reversible A/C).
And it’s not just about whether the coils can defrost. The whole machinery and refrigerant are different. A cold climate heat pump has a setup that is more similar to a freezer than it is to an A/C.
Sorry about the downvotes. People need to re-learn internet etiquette.
This is the most informative answer yet. Thanks.
Thanks for spreading correct knowledge, as someone who works for a manufacturer of heat pumps it’s refreshing
I have never seen so many winter tires, and studded winter tires, as I did on my trip to Sweden last winter.
I think they are mandatory there.
You used two temp scales in the same sentence
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You asked, you got it.
Educated adults know not to do that, and now you’re educated. Good luck out there
My air heat pump has been ticking away happy for 15 years with no issues. It’s worked fine warming up the house when it’s -20°C in the winter and cooled nicely in the up to +30°C in the summer.
I do supplement it using electric heating and a fireplace though.
Thank you for responding and sharing your counter-experience. Greatly appreciated. What keeps your unit from icing over? Are they designed differently in northern climates?
Here’s a good video showing how the heat pump will reverse and basically dethaw the coils when it freezes over: https://youtu.be/7J52mDjZzto?t=1317
They’re spreading all over the Alps too. Easily a 50° temperature difference between summer and winter, and they tick over nicely for years with no problems
I think in Europe it’s a fairly common method now so reliability has been sorted out.
Generally the US is a decade or so behind everyone else though so it might take a while
The COP coefficient falls down drastically to 1 as soon as temperature drops below -5C and they basically start working as an electric heater. It wouldn’t be a problem if I wasn’t living in a country with the most expensive electricity in Europe which is produced mainly from coal…
Yeah that’s just incorrect. People wouldn’t use them then. All new build chalets have them
Then you’re looking at the wrong models.
The Mitsubishi H2i has a COP of 2.88 at -15 C (5 F).
There are also models with COP above 2 at -30 C.
Yes, a typical A/C isn’t designed for subzero temperatures. But you gotta get the right heat pump for the right climate.
For cold climates, it does get more expensive and less efficient and at some point it will always be cheaper to just burn wood or fossil fuels. But with the right heat pump, even very cold climates can get most or all of their heating cheaply with a heat pump.
Hah look at the downvotes, you can’t have civilized discussion these days.
Your last paragraph and my last sentence is the whole culprit for me. The money I have to pay here for good heat pump with COP 2 at -30 and the associated electric bills have currently no chance here to ever be cheaper than burning gas either nor more friendly for the climate where my government burns coal to produce electricity.
And no, I cannot install enough solar to power this heat pump in the winter or offset the cost of electricity during summer (inverters already turn off in the summer, no electricity is produced as too many neighbors have solar and voltage rises above shutdown threshold in the grid)
Solar in winter for high latitudes is never gonna work, fully agree on that.
But at some point a hybrid system will be cheaper for part of the year than a pure gas system, at any latitude.
Whether it justifies the investment is indeed a cost/benefit analysis.
Downvoting on Lemmy is toxic, fully agree on you there. It really stifles healthy discussion. It seems Lemmy is engineered by communists who only want agreement lol. 😂
Yes, there are cold weather heat pumps that can thaw the coils to keep operating. There is a point where they just can’t continue to operate.
When I design a heat pump system in cold climates, I always include a secondary hear source that kicks in if the heat pump gets overwhelmed. Might be a gas section in a furnace. Might be an electric heater in a fan coil. Might be electric baseboards or wall heaters.
Theres different technology but there are some that can function to -32° F and they often have a feature that allows them to detect when theyre frozen up and defrost and then automatically switch back to heating
Many parts of Canada will regularly see colder than -40F, so I can sympathize easily with a view that solely relying on them might not be safe in that environment.
It’s fine. We use geothermal heat pumps with the lines buried below the frost line. (6-8 feet below the surface.) I know quite a few houses and even a few factories (30,000 square feet+) that use them in temps that drop well below -30c to -40c without any issues.
The initial setup cost is a fair bit more because of having to bury the lines, but after that they’re fine.
Oh I have no idea, I just got to this thread and see you’re at -6.
It’s weird because I thought it was an informative post. Made me want to look more into it and if it was just a subsection of heat pumps that was affected.
I think because I left open the possibility that there’s any utility at all to fossil fuel usage, they’re treating me like a whacko that’s hoarding incandescent light bulbs because I believe LED light bulbs are distributed computing nodes for mind control space lasers or something. I’m not - I was reacting to the article based on my experience with a mini-split heat pump that can’t handle a week of 15F weather without freezing into an iceberg, even with a defrost cycle.
Mind me asking what yours cost?
Just got a Toshiba unit installed in Norway and it was $3500.
Built in de froster.Price might be what makes yours strugle in colder temps.
Mine has Toshiba guts. I don’t know what I paid for it - now it appears to be selling for $1100. Mine defrosts but its defrost cycle just turns on AC for a bit instead of heat. Edit: Mitsubishi guts.
Man they pitchfork mob came out in full force for this one. I also live in the south and during the freeze of 2021 it was a struggle for it to deal with those low temps.
That’s precisely the freeze that led me to experience the inability of my Senville mini-split heat pump to keep up. So glad I had a wood stove. Even then, my shower drain trap froze solid. I was living in an “insulated” yurt at the time - good floor insulation, and somewhat okay wall/ceiling insualtion.
My attic insulation needs work. I swear I’m gonna get that sorted this year now that the heat has (hopefully) calmed down.
There absolutely have been new heat pumps hitting the market in the past year or two that are blowing away the previous generation.
Your mini split probably doesn’t have a defrost function. This would all be specified in the users manual.
Oh it does, it’s just that it the defrost cycle in 15F gets off just enough ice for it to barely work, and this was when it was brand-new and verified to be working properly. I now understand that it is just not designed for ultra-cold weather, and that some are better suited for such demands.
That does kind of only it could need a recharge. These cheaper units don’t actually have active monitoring for ice buildup - they just do it on a schedule based on temperature (and sometimes humidity). If you are getting ice buildup, it’s either outside the rated performance envelope, or it is not functioning as intended.
I think this really highlights the crux of the issue, which is just that the “tribal knowledge” of how to operate the equipment isn’t there and it’s something that education would probably help.
Like, many people’s fathers have probably shown them how to relight the pilot lights on their furnaces and hot water heaters. And if not, the “handy person” on your block would know.
Understanding how to own and operate heat pumps effectively might not be as second nature.
Understanding how to validate the extreme weather functionality of your heating system is super important. Knowing the difference between “normal” and “something is fucked up”… especially before an extreme weather event is pretty important. I’m pretty handy, but absolutely nobody in my area runs heat pumps residentially…
… but that’s probably just because of a lack of uptake rather than a real economic reason. Solar is exploding in my area as a result of increasing power costs and a great environment for it.
As it’s adopted and as people learn how to use, maintain and troubleshoot them I expect problems like that will become more sparse.
Yes, most installations do require a backup heat source in the event outside temperature is too low for optimal heat pump usage. On my ecobee thermostat, you can set what this temperature threshold is (i.e. 20F) and then if the outside temperature falls below this value, the heat pump is stopped and the natural gas in my case kicks in. Granted, this doesn’t happen often where I live, but for those few weeks in the winter, it is not something I even have to think about. And the rest of the time, I am saving money using the heat pump and not natural gas.
I doubt there can ever be high tech heat pumps which can operate at -25 C or less, because there’s so little heat energy outside and the heat pump would probably spend a majority of the time running in reverse to dethaw the unit to prevent it freezing over.
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?
create energy
Ummm… that’s not how it works.
Here in Massachusetts, the belief is that heat pumps do not heat well when the temperatures reach 0F
That’s -17.8 C, so pretty close to the limit mentioned here
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.
So this is exactly what the article is about and up to -4 f heat pumps are more efficient.
If your the son of an hvac guy maybe your information is based on older installed units. I had a heat pump installed in my fathers home in the northeast ( non coastal) and I was shocked it ran well all year. I had heard the some rumor that you had.
Technology advanced and facts change.
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.
That doesn’t say anything about gas prices.
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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.
Continue? You can’t stop it even if you wanted to, unless you pervert the natural climate cycles somehow. We are exiting a cold period and it has nothing whatsoever to do with using gas or come farts.
You mean this natural climate cycle?
[After setting your car on fire] Listen, your car’s temperature has changed before.
Oh fuck! Are you a climate change denier?! Are you joking, too? or do you still believe this is a natural change?
The climate changes. There’s no denying it. No it isn’t caused by cow farts so everyone needs to? eat bugs instead, and no it isn’t caused by driving your car so you must become a serf and be bound to your lords 15 minute plantation.
Dont know what happened, but i can’t see this comment thread anymore. Maybe it’s been deleted.
Whatever happened, you are absolutely full of shit.
Maybe you should try listening to scientists instead of talking about cow farts. There is an insurmoutable amount of information and proof that the climate has warmed drastically in the last 20-100 years and it doesn’t follow any recorded pattern of warming and cooling since the dawn of humanity ~200000 years ago.
Heres a nice image showing the data in simple terms.
You xan continue to dwny it all you want, but any rational person will ignore you.
Incidentally, dont pay attention to mass media, i hear a claim i look at the facts and draw my own conclusions. You should do the same.
If you’re on propane, it’s more likely to be cheaper.
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.
Well, some people don’t put money higher than the ability of humanity to survive.
So the cost is less relevant than the pollution.
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.
Maybe your information was just not factual?
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…
