It makes sense as a long term move because now you have a single point of change to switch to renewables. Suppose there is an unprecedented improvement in solar efficiency or power storage tech in 5-10 years or a nuclear power plant gets built. Then you cut natural gas usage to zero at once, which would have been impossible if all the houses still depended on it.

You can use the same argument for electric vehicles.

Sort of?

We don't use electric vehicles for heat, so they are sort of fuel agnostic when it comes to where the electricity is coming from; we burn fossil fuels to make heat or electricity.

The future proofing argument makes some sense for California. Coming from the Northeast heat is a lot more important, I'll do a new HE Gas Boiler for 12k in a single family this year, converting from oil...save me probably 2k a year. If that were electric heat I'd be paying 400% more every year which would be insane.

https://www.mass.gov/info-details/household-heating-costs#co...

Agreed. I used to live in Alaska, and when my wife and I bought our first home there, the furnace was broke and we couldn't afford to replace it right away. The electric baseboard heaters cost us $900 to run just for that January!

And that's exactly why this is being done in California, isn't it?

It can be more efficient to burn gas at the generation plant because electrical heating can be 3-500% efficent by using the energy to move, rather than create heat.

A similar argument applies to electric cars. Electric motors are so much more efficient that they still beat the alternative after being transmitted and stored in a battery even if the original source is burning gasoline to generate electricity.

That's before getting into carbon and pollution.

Heat pumps are only efficient down to a bit below freezing temperature, so it may make sense for Berkeley, but it gets really expensive if winter temperatures get much colder.

"efficient" is a little vague.

Ground and water source source heat pumps can keep their efficiency down to extreme temperatures as their source maintains its temperature. Air sourced heat pumps can go down to -20C and still be above 100%,(though this is notably below their peak in warmer ambient temperatures) and they often have fallback resistive heaters that are independant of outside temp and are 100% efficient (though probably not sized to work alone generally).

So whether they are efficient and expensive really needs a complex comparison including up front investment in digging trenches for geo or pipes, ongoing costs of fuel, predictions of heating and cooling days for the region, whether insulation makes more sense than more heating and so on. I don't think there's anything that strictly rules out heat pumps in most places people live or restricts them to California.

Stockholm getting heat from the North sea is a good example of their counterintuitive potential in colder climates.

Ground-source heat pump installation is expensive - estimate by a vendor near Boulder, CO $30k/14 year pay-off for residential - http://www.energyhomes.org/pricing.html but a bit light on details of their assumptions.

A heat pump being "efficient" can casually be thought of as "multiples better than just resistant heating" (but is measured in cooling and heating efficiency, seasonal performance, etc.)

This drives whether the heat pump is economical or not, because the more heat you have to produce directly from electricity, the less economical your installation is, compared to other heat sources. A gas vendor in Washington, DC area estimates annual savings of $1,500+ by using natural gas heating and water heating over electric, including air-source heat pumps, and significantly lower lifetime costs: https://html5.dcatalog.com/?docid=2db77d07-d752-43b8-bfaa-a8...

Even the gas vendor in a country with famously low gas prices and an aversion to pricing in carbon seems to put it as a close second, well ahead of propane or oil on operating costs.

You say $1500 saving but that's against resistive heat, not heat pumps, which are only 150 to 350. Which could be small enough a difference that providing cooling with one system may cover it.

And those are only operating costs, and I'd guess if you didn't have a gas grid magically installed for no cost, then propane or oil are the two options you'd more realistically go for rather than pay build a gas connection, whereas a house without an electric grid connection is pretty rare and could be considered a sunk cost in most cases.

Obviously for many existing homes you do magically have gas pipelines for free, but in the context of new builds, you'd want to compare those costs.