Better building codes for insulation & air sealing, and air source heat pumps, which can provide 5kW of heat for 1kW of electricity depending on the weather & unit.
As far as I hear the operating performance is mostly there with the heat pumps, now they just need to bring down the unit cost (and do a little more work on performance in very cold weather)
There's still the problem of powering the heat pumps with clean energy in winter. It has to come from somewhere. These polar vortices aren't getting any milder. This is a massive slice of the energy pie that requires discipline and planning to decarbonized. I worry because I perceive complacency due to cheap natural gas and I fear we won't come close to decarbonizing enough unless we're serious and quantitative. How many new kW of heat pumps would it take to heat the US Midwest through a winter?
I'm not close enough to the problem to identify the solution with authority, but there are many options. Most significantly to me, long distance transmission lines will hopefully allow sunny Arizona to sell power to wintery Minnesota. But I do agree about the pitfalls of complacency.
The beautiful thing about electrification is its source agnosticism. You can put in heat pumps today, power them off natural gas turbines for now, and switch out to something better in the future at will. As long as your heat pumps can achieve COP of ~2 or better for most of the winter, they should have comparable overall efficiency if we assume the electricity from the natural gas plant is in total about 50% efficient.
Over here heat pumps are quite popular (both ground source and air). Problem is people size them so they can get through most of the winter, but for cold spells they're not enough and you need supplemental resistive heating.
Sure, cost optimal for the individual consumer, but for the entire grid?
Depends where you are: in a lot of places, it only gets cold when a weather system moves in, which means lots of wind power available.
The backup power could be propane, but electric-resistive is still cheaper.
The other issue is that air source heat pumps should really create blocks of ice from municipal water and then dump them in the yard, instead of trying to squeeze heat out of cold air.
Where I live, cold spells unfortunately tend to coincide with very low winds.
And yeah, adding a supplemental resistive heater to a heat pump is certainly a lot cheaper than adding a separate combustion based backup heating source.
For some reason, we don't really use propane over here, except for running grills in the summer, or for boat stoves etc. Fossil fuel heating for houses tends to be fuel oil, though that is on the way out.
As far as I hear the operating performance is mostly there with the heat pumps, now they just need to bring down the unit cost (and do a little more work on performance in very cold weather)