The notion that heat pumps don’t work at low temperatures hasn’t been true for years. I think you may be surprised to find that just about any heat pump you look at has good efficiency down to very low temperatures.
That’s true, but still doesn’t always make heat pumps the most cost effective choice to operate. For example, last winter I paid an average of $0.24/kWh for electricity vs $0.05/kWh for natural gas. Even if a heat pump had a perfect 4.0 COP all winter, gas would be ~15% cheaper. Electricity prices really need to come down before it will be viable for everyone.
This varies quite a bit based on location for instance here in Florida natural gas is $0.13/kWh while electricity is about $0.12/kWh, also where I live there is no piped NG so it would be propane delivered to a storage tank which is even more expensive.
Also the winters are mild here so basically everyone has either a heat pump or the further south you go it's just heat strips because heat is rarely used so not worth the cost.
So any kind of blanket statement about heat pumps vs gas heat would be folly, but due to improvements in cold weather heat pumps and solar power are allowing them to make much more sense in more places.
There are many advantages to decoupling fuel combustion from its energy use, burning NG at a power plant relatively efficiently with much better emission controls, then distributing on electric grid for use more than just heating, while allowing the home to heat from many different energy sources and allow for grid down backup as well.
Does your 0.05/kWh include the distribution costs? The thing to do once you go to heating with gas is to just switch completely to electricity and turn off gas. In my experience (admittedly not in the US, but several other countries) distribution cost often more than double the $/kWh for natural gas (especially if you only heat part of the year).
Not to mention, lots of places have time of use electricity pricing which makes it even worse. This is the problem with running my heatpump when its cold, some of the coldest times (right before dawn) coincide with peak time-of-use prices
ASHRAE—an HVAC organization—has data on the coldest and hottest days for areas so that you can design things for the coldest or hottest 1% of the year (4 hottest/coldest days):
I think that if you have an older, leaky/ier, less-insulated house you may need to 'brute force' heating your (probably older) domicile. But if you have a <4 ACH@50 air tightness, and reasonable insulation levels, a good portion of the US population could make do with a heat pump.
Mitsubishi publishes data were they have 100% heating capacity at -15C, which some models being 100% at -20C and -23C:
That's one of the older style units. Starting in 2007 when Mitsubishi introduced their "Hyper-Heating Inverter" heat pumps, and continuing with Fujitsu and Daikin following with similar technology in the 2010-12 timeframe, and others a few years later, heat pumps got way better in the cold.
Mitsubishi's maintain 200%+ efficiency down to -4℉ (-20℃) and 150% down to -22℉ (-30℃) [1]. Only a few towns in the continental US get below that, and even those aren't going to get cold enough long enough to make it worth it an an all electric home to switch to your emergency electrical resistance heating.
Their capacity doesn't start dropping until you get down to 23℉ (-5℃), dropping to 76% at -13℉ (-25℃).
I've got one about 8 years old, and it does just fine down to 0°F (it hasn't gotten colder than that here). It doesn't even have any kind of auxiliary heat.
It's fine. The only difference when it's super-cold is that the air coming out of it isn't as warm, so the heating cycle stays on for a longer proportion of the time. But it keeps it 70°F inside no problem at all.
crgwbr|4 months ago
SigmundA|4 months ago
Also the winters are mild here so basically everyone has either a heat pump or the further south you go it's just heat strips because heat is rarely used so not worth the cost.
So any kind of blanket statement about heat pumps vs gas heat would be folly, but due to improvements in cold weather heat pumps and solar power are allowing them to make much more sense in more places.
There are many advantages to decoupling fuel combustion from its energy use, burning NG at a power plant relatively efficiently with much better emission controls, then distributing on electric grid for use more than just heating, while allowing the home to heat from many different energy sources and allow for grid down backup as well.
https://www.eia.gov/dnav/ng/ng_pri_sum_a_EPG0_PRS_DMcf_m.htm
https://www.eia.gov/electricity/monthly/epm_table_grapher.ph...
cycomanic|4 months ago
doctorhandshake|4 months ago
etimberg|4 months ago
kragen|4 months ago
sokoloff|4 months ago
The CoP is often around 2.0 at those very low temps, though (and of course the heat energy demanded is higher).
Loughla|4 months ago
Mine struggles if it gets below 30, and might as well not exist below 10. They're not great at low temps.
throw0101a|4 months ago
What percentage of the (US) population gets temperatures like that? That's generally mostly IECC Zone 7 (though cold snaps in Zone 6) can happen:
* https://basc.pnnl.gov/images/iecc-climate-zone-map
ASHRAE—an HVAC organization—has data on the coldest and hottest days for areas so that you can design things for the coldest or hottest 1% of the year (4 hottest/coldest days):
* https://ashrae-meteo.info/v2.0/
I think that if you have an older, leaky/ier, less-insulated house you may need to 'brute force' heating your (probably older) domicile. But if you have a <4 ACH@50 air tightness, and reasonable insulation levels, a good portion of the US population could make do with a heat pump.
Mitsubishi publishes data were they have 100% heating capacity at -15C, which some models being 100% at -20C and -23C:
* https://www.mitsubishielectric.ca/en/hvac/home-owners/zuba
At -25C they have 80% capacity:
* https://www.mitsair.com/wp-content/uploads/2024/10/MEM-20240...
tzs|4 months ago
Mitsubishi's maintain 200%+ efficiency down to -4℉ (-20℃) and 150% down to -22℉ (-30℃) [1]. Only a few towns in the continental US get below that, and even those aren't going to get cold enough long enough to make it worth it an an all electric home to switch to your emergency electrical resistance heating.
Their capacity doesn't start dropping until you get down to 23℉ (-5℃), dropping to 76% at -13℉ (-25℃).
[1] https://www.coolingpost.com/world-news/study-proves-heat-pum...
doctorhandshake|4 months ago
Mitsubishi hyper heat is indicative of a contemporary inverter design - 100% efficiency to -5f: https://www.mitsubishicomfort.com/articles/mythbusters-heat-...
crazygringo|4 months ago
It's fine. The only difference when it's super-cold is that the air coming out of it isn't as warm, so the heating cycle stays on for a longer proportion of the time. But it keeps it 70°F inside no problem at all.