[woutgaze]

Does anyone know something similar for Europeans (I live in The Netherlands)? Common units used here are all metric; for heating I've seen Natural Gas Usage (in m3) used and GigaJoules. Also almost no-one here seems to use air conditioning.

[8fingerlouie]

The easiest (and very crude) solution is probably to find the amount of gas you use per year in m3, then calculate the amount of kWh heat that yields. 1m3 of gas produces approximately 10.55 kWh of heat, depending on the type/age of your furnace.

That is the amount of heat you require over a year.

Through the magic of heat pumps, you can find the COP value of any model you plan on purchasing, but in essence the COP value tells you how much heat the pump will produce when using 1 kWh of electricity, for instance a COP value of 3.62 means the heat pump will produce 3.62 kWh of heat for 1 kWh of electricity.

So say you have a yearly gas usage of 1600m3, that equals 16880 kWh of heat. Assuming a heat pump with a COP value of 3.62, you can then divide the 16800 by 3.62 to find the amount of electricity you will need with that particular heat pump to produce the same amount of heat, in this case 4663 kWh.

As i said, this is a very crude calculation, and it doesn't take into account that the heat pump efficiency drops as temperature drops to around it's lowest efficiency temperature (for mine it's -25C). When that happens, it has a built in backup heating device that will do regular electric heating, meaning 1 kWh per 1 kWh.

It also doesn't take into account climate control built into many european heat pumps (and maybe american as well ?). Mine has an outdoor sensor that simply shuts off the heatpump whenever outside temperature goes above a certain point.

And then there are all sorts of after market upgrades you can buy, like Tado, who produces a "sensor" for certain heat pump models, which will further reduce consumption based on local weather forecasts, AI and other readings.

[bake]

I'd suggest asking the folks at https://lun.energy, to start.

You're right that our site doesn't yet work for homes outside of the US, unfortunately. The approach would be similar, but some different equipment and home configurations to consider along with different data sets (fuel pricing, weather, grid emissions, etc.) -- I'll keep an eye out for good resources, and would love to help anyone who wants to try to build it!

[pjc50]

Interesting site, although once you go deeper than the front page it's in Swedish.

[Glawen]

In Europe we have water based heating system, be it radiator or floor heating. That changes the equation quite a bit, and also impact what type of heat pump you can install (low temp or mid temp).

The best is to have a hybrid system: a heat pump and a gas/oil/wood boiler which will fire up when it is freezing.

[pjc50]

I'm .. suspicious of hybrid systems. I've encountered a company which was pushing them, and I don't like the idea that I'll be paying gas standing charge and installation cost for a very rarely used boiler.

[bake]

I am as well. I started out my own journey convinced that we should keep our existing high-efficiency gas furnaces for backup heat, but when we finally did the math, it would have saved us a whopping $3 over the last twelve months vs. using electric resistive backup, and that was using last year's cheaper gas prices...

In the US, if you need backup heating (and you may not, with the heat pumps that are on the. market today), electric resistive heating (heat strips/coils) is indeed more expensive than high-efficiency gas furnaces BTU-for-BTU, but remember that resistive heating runs in parallel with the heat pumps, whereas furnaces have to take over entirely for dual fuel systems. Natural gas might be cheaper than electric resistance alone, but electric resistance plus the heat pump even at diminished capacity can be a very different story.

[sokoloff]

By the point that heat pumps are going to need supplemental heating, the heat pump is probably operating under a 2.0 CoP (and maybe close to 1.5), so at some point, electric resistant heating (CoP of 1.0) isn’t that much worse than a heat pump in super-cold temps.

(The huge win is the 99% of the year where supplemental heat isn’t needed.)

[vba616]

>The huge win is the 99% of the year where supplemental heat isn’t needed

People advocating for heat pumps seem to be convinced the normal climate, if it isn't warm all year round, is in-between for most of the year. I have never learned why.

Where I live, and it's not Alaska, northern Minnesota or Maine or something like that, there can't be any "win" for six months of the year because there's essentially no need for burning gas anyway. That's separate from the question of exactly how cold a heat pump can be effective.

But from November through April, lows here range from the high 30s to below zero (F). Based on some poking around .gov websites, that is plausibly well into the resistive range.

And again, it doesn't matter how well it works above 40F, because all of the months (6) with lows above 40 require virtually no furnace use.

I've been told that my experience with a heat pump in an apartment where it had to be set to "emergency" (resistive) heat all winter is outdated...but I can't shake the feeling that people are not understanding climates where heating is needed in the first place.

[sokoloff]

Even at 17°F OAT, a modern heat pump can be over 2.5 CoP and deliver 90% of its rated capacity. [1]

Even on a day with the low in the teens, the high was probably 10-15° higher. Look at the hourly bin data for your location, not just the daily/monthly lows.

The key with a heat pump in a heating dominated climate (on top of insulation which is needed for any energy source) is sizing it right, creating the ducts right, setting the control strategy to not use H2 (emergency heat) too liberally, and not using deep setbacks that will flip you into H2.

Just as you are rightly skeptical of people who can’t comprehend not installing AC, you might be skeptical of drawing too strong and long conclusions from one heat pump install in a rental of unknown quality and where the incentives aren’t aligned to trade-off capital vs operating costs.

[1] https://www.pacificairconditioner.com/files/Hyper_Heat_for_r...

[ars]

> whereas furnaces have to take over entirely for dual fuel systems

Why is that? I see no reason you can't run both, other than a more complex thermostat setup - probably something with an outdoor reset, that kicks in when outside temperatures are too low.

[brnt]

The Koevlaas formula: https://nl.everybodywiki.com/Koevlaas_formule