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Comment by londons_explore | Hacker News Reader

Numbers from 1 hour ago... From the UK, and assuming UK climate for COP figures. ~True with both retail capped prices, and wholesale market prices.

There are still people in the UK installing heat pumps. Either they have a very rose tinted view of the future direction of electricity prices Vs gas, a rose tinted view of future government taxes/incentives, a rose tinted view of the environmental benefits (eg. By looking at aggregate CO2 emissions instead of marginal CO2 emissions), or they have been misled by installers/builders who make substantially more money if they install a heat pump.

Either that or I got my maths wrong. But I don't think I did.

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from the UK - groundsource vs air-source heat pumps makes a huge difference. Last i checked:

- ground source was roughly parity with gas (with something like an 8x higher install cost)

- air source heat pumps were more expensive to operate but similar on install costs

However comparing on cost only misses the point, a heat pump is generally capable of cooling as well, which is becoming more of a necessity in the summer.

P.S. You can do silly things with ground loops like use excess solar power to cool during the summer or daytime storing that heat in the ground, then removing some of it in the winter/nighttime.

I'm installing heat pumps in the US.

* I'm tired of tenants installing window air conditioners.

* I pay for steam heat myself whereas tenants will pay for electricity used by their heat pump.

Thank you! And I can venture a few more hypotheses (from least to most likely):

1. Altruism

2. Already committed

3. They have a pessimistic view of future gas prices.

4. They have solar.

5. They're in a long tail/corner case/different use case from the one you computed.

I'd put my money on 5, depending on how big a % difference. Eg. I've noticed more and more people switching to solar as prices come down and hit an inflection point for them in their use case. Wouldn't be surprised if heat pumps are the same.

Can you expand on the aggregate CO2 vs marginal CO2 part ?

I’m looking into installing a ground heat pump in a new house (coupled with solar panels) mostly for environmental reasons and all the critics I’ve read so far were about the costs.

If you turn on a light and use some extra electricity, some power station somewhere will need to increase power output to provide for you.

It's the CO2 production of that extra generation, known as marginal generation, you should care about, not the nationwide average.

Most of the time, in most of the world, that extra generation is combined cycle gas turbines at ~50% efficiency.

For most people, the only time a new use of electricity is eco-friendly is when all the energy in a country is already supplied by wind/solar/hydro, and therefore a newly switched on thing also gets supplied by wind/solar/hydro.

Obviously the decision to installation a heat pump depends on the marginal generation in 15 years when you are still using that heat pump. That's very hard to predict.

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