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Heat pumps twice as efficient as fossil fuel systems in cold weather, study finds
(www.theguardian.com)
this post was submitted on 12 Sep 2023
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Technology
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Correct (although $0.063), and interesting to see you seem unfamiliar with this, this is the standard way of listing energy prices in Europe, it's not just that site. That site was just my first hit when I looked up Canadian energy prices. It's the low heat value and it's determined by the energy in a fuel if not allowed to condense (which is the relevant value for a traditional furnace, if you have a more modern condensing furnace you take the high heat value) and it makes it relatively easy to compare different sources of energy.
What people never realise is that being far up in arctic climates doesn't only impair an SCOP. Yeah the lowest temps are very cold, but that means temporarily bad COPs. An SCOP is made up of the whole heating period though, which in colder climates is longer, so in turn you have several months more of the time where heat pumps are extremely viable with temporary COPs above 5 or 6 saving loads of energy. The real problem is if your lowest temps are so low that a heat pump will stop working entirely, in which case you get a hybrid system or just leave your old furnace in as backup, which is even better for your SCOP because you omit the month(s) with the worst COP and only use the heat pump when it's most viable. Let's say you live in Tuktoyaktuk and heating period is basically all year, then you have your furnace on for 3-4 months but you're saving massive amounts of energy with your heat pump in the other 8-9 months of the year.
I actually tend to avoid using that term for heat pumps anyway, as it's not really correct in terms of physics. What makes heat pumps so viable is a coefficient of performance, their actual electrical efficiency isn't all that good at 50-60%, but it's also kinda irrelevant. It's sometimes easier to just call it efficiency, but like you say, once you go into the nitty gritty it falls apart.
It depends. It's certainly economically and CO2 efficient. Thermodynamically? That's something for physicists and engineers to worry about, not J. Random Bloke.
I've seen plenty of old houses over here in Germany which did have a gas furnance that was somehow under-dimensioned -- the idea is that in the real cold days you'd still have the good ole fireplace (or coal oven), as well as not so old houses which still have one because sitting in front of it.
Gets a wee bit more complicated with heat pumps and maximising the efficiency of everything as the fireplace needs to be hooked up to the heat exchanger or there won't be any hot water and modern units are closed and look rather different, but you still get a window and plenty of infrared radiation.
Then, last but not least, there's insulation. Especially up in the arctic you should be doing your darnedest to build passive houses. Certainly possible in Kiruna, I've heard that the Norwegians are trying on Svalbard.
Oddly enough I've never encountered that in Germany, I only ever see catastrophically oversized furnaces that start cycling in March... Seems to me plumbers never really worry too much about correct dimensioning, they just put the same 20 kW furnace that they know and love to install in every apartment and single family home. For some it will be somewhat adequate, for some it'll be oversized, who cares, customers never complain when the furnace cycles, but when it's too cold, you've got a problem. Same as they're never too worried about finding suitable supply water temps. Just set it to 80 and you're good, it's the customer who pays horrendous gas bills, not you lmao. That's also why everyone thinks their Altbau has to have 80°+ supply water when they have never really tried anything lower to see if it maybe suffices. My parents had their oil-furnace on 80C supply for the past 40 years and last winter when everybody was trying to save as much energy as possible they figured out you can set it to 55 as well.
I like you.
I agree, there's a lot more to it than just the argument that was presented. I am also woefully unfamiliar with measurements of energy in common use, and sort of come at things from a more physics mindset. I'm no physics major, but it just makes sense to me that way.
Personally I'm a fan of heat pumps. There's plenty of reasons not to go that route, but when it comes to electrically driven heating and cooling, you'll be hard pressed to find a better alternative.
I'm in the camp of going independent with power. Getting solar, a battery system, and converting everything to electric. That's the plan at least. If my power is free (from solar) then if I lose some efficiency in the conversation, that's okay, it's free power either way.... though, not "free".... just, I'm not paying per watt (or kWh) I just need to buy the material to make the system go.... that's not free, but day to day operations are. If I'm making sense.
I'm not where I want to be yet, everything is a work in progress for now. I still have several natural gas systems in the house, including the furnace. I can't afford to do everything all at once. My current plan is to buy and install a grid-tied solar system, with the option of batteries, in the near future. Maybe the next few years. We have a good South (ish) facing roof above our garage which will be ground zero for solar panels. It's sizeable, so hopefully 20+ kW of solar will fit.
After that's in, start working on electrification inside, make sure our grid connection is up to par, and start replacing and upgrading our furnace/water heater/whatever with electric counterparts and try to make everything as efficient as possible.
When finances allow, buy a battery system that can power the house for ~24-48h, based on usage, and add it to the solar system. Maybe start with 10-12h worth, and upgrade as we go. I'm thinking of getting the rack-mount LiFePO4 packs, and starting with around 4 (~20kWh), and go up from there. I'm an IT guy, so racks are a go to for me. As finances allow, pick up another pack to bring it to 5, and another, and another, etc, until we hit my goals. The goals are very specific and I have reasons to want 20+ kW of solar, and 2 days of battery backup. Our area supports net metering, so we should be good to start on the plan. It's going to take decades to get it done.
This is all very off topic, but I figure were so far down this thread and so deep into the bowels of post history that nobody but you and I will be reading it. I felt like sharing my plan; for no other reason than to say it out loud.... more or less.
Heat pumps are in my future. So regardless of all other factors, like "efficiency"... that's what I'll be doing. Hybrid is definitely an option, though, I'll probably go with "dual source" (heat pump + electric resistive) for my system if possible. We're pretty far south in Canada where I am (Niagara region) so I'm ok for the heat pump to provide 100% of my heating for over 99% of the year. We only occasionally get cold spikes into the -30c range for a few days at a time at most... but I'll get crucified if the inside temp drops too far (the Mrs will see to that). In the interest of electrification, I'm hoping to get a resistive electric heating system for the alternative heat system. It's not as "efficient" as the heat pump, but when the heat pump won't work because of the extreme cold, it's the next best thing IMO.
I want a battery system because I don't want to be down if the grid goes away, and I want enough battery that we don't have to rush onto the roof every time it snows, to clear the panels else we need to run on grid power.... having some leaway in how much time we have to deal with the problems that might prevent the system from working, will be perfect.