Only in Texas. Everywhere else they’d raise the rates.

COP is the ratio of moved heat to electricity used. Modern air-to-air heat pumps can maintain a COP of 2.5 or more below 5 def F. The 2.5 COP is important because it’s the efficiency cutoff where, above that, even using methane (natural gas) to generate electricity, send that electricity to the home, and use that electricity to power a heat pump, you will use less methane than you would if you burned it directly for heat in your home.

A COP greater than 1 will still be better than resistive heat, and many modern heat pumps can maintain a COP above 1 well below 0 deg F.

Now, wherever you live, methane could be subsidized for homeowners, so the direct costs to the homeowner don’t pencil out directly at the 2.5 COP cutoff, but that’s no longer a question about efficiency, but around local government not correctly pricing methane.

EDIT: there was a week in January where it stayed below -10 deg F where I live, and my heat pump kept my apartment at 70 deg F with no issues, and only needed to run 27% of the time.

In addition to Thejevans points, your cost estimate is very high. That cost would be in line for a geothermal heat pump, which is far more efficient. Air to air heat pumps can be installed for more like $3-10k in most residential homes. And on the higher end that is a big house that is probably saving more than $550 a year.

I had a new multistage NG furnace, a heat pump, and a garage heater installed for 24000$, with a 6k rebate coming my way. Where did you get your numbers?

I did this about a month ago.

We hit 0 degrees a month ago and the heat pump was not running. Only the furnace would run when it was that cold. I’ve read that they can work down to 0 though, so I think the installer might have configured it wrong. I’ve been meaning to call them to get that looked into.

What you’re missing is that heat pumps move heat, instead of just turning electricity into heat. How efficient they are at this varies by heat pump, and by outside temperature. During extreme cold, you might really spend more, but the rest of the year, you end up moving 3-5 kwh of heat for each kwh you consume, so your overall bill over the course of a year ends up being lower.

first you would need to know what COP you could reasonably get, which among other things depends on the average outside temperature during heating season if you want to use an air sourced heat pump.

The COP can be in a largish spectrum depending on these factors but typical values are 3.5 for average homes in temperate climate. Higher if you live in a warmer climate and lower if you live closer to the arctic. If you want to really do the math it might be good to get help from a professional specialising in heat pumps.

Edit: this is for heating use only. A heat pump can also be used for cooling but then the climate effect is inverted.

Why does -10f mean you MUST have a gas furnace? Most modern cold temp heat pumps still have COP’s 2.5 to 3 at that ranges. Just look at the energy star database and then find a spec sheet for one of the cold wether ones.

Secondly, look into the actual cost of the unit, the largest air source ones like you mentioned are often in the 7 to 10k range, so take that, subtract the 2k fed subsidy, then the 3 to 4k of the one way heat pump (ac) it replaced. Admittedly, if your getting multiple weeks of -10 the benefits of such a high efficiency AC probably don’t have much effect.

Although, if your building new in zone 5, you probably should be looking at ground source rather than air source. It’s is actually a lot more expensive to lay the pipe and install, 20 to 30k, but that is a lot easier to do that before landscaping. Obviously the benefit is a lot higher efficiency at cold temperatures, given that the outside air temperature doesn’t have any significant impact on the output efficiency or capacity, as well as much lower energy useage.

Solar is also something to poke at if you have yard space or are planning a decent roof, especially if you’re not afraid of technical documents and at forum posts to do it yourself as diy often haves the cost. Pannel and inverter prices keep coming down, to the cost will probably be better by the time you actually build. I have supper cheap electricity (10c) and still a sub ten year net profit.

The extra 30 to 60k (depending on diy or cash grab company) is steep, but in the context of building your own house, the extra 50 to 100k for both geothermal and solar mean basically negligible utility payments for the rest of your life, outside of water if you don’t need a well, as compared to still having to pay in thirty to forty years, but now with that many years of price increases and inflation. Especially if we end up getting a carbon tax in fifteen to twenty years and utilities do what they did in Australia and massive jack up prices in protest, not that they saw anything but massive windfalls or lowered prices after it was repealed of course.

Given the large number of gas export terminals already approved and under construction, I’m expecting US gas prices to at least double over the next few years, bringing them up to match the international LNG price.

Is solar an option to offset the cost?

It’s not a huge change in unit design to be able to do that, but most AC units sold in the US have historically not had that capability built-in.