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Comment by danek_szy | Hacker News Reader

What technology are these heat pumps using that make them "energetically basically free"?

They have very good thermal coeffiency: ground source heat pumps will typically generate 3-6kWh of thermal energy from 1kWh of electricity. By reversing the flow you can also use ground source heat pumps for cooling as well.

Doesn't sound like "basically free" to me... It still uses electricity, which doesn't help with climate change (even if it mostly comes from renewables).

Hard to see how you can read what GP said as anything other than "basically free", and failing to quantify, like you are doing here, and just categorically calling all electricity use bad is not coherent or helpful either.

Swedish electricity generation is 99% low-carbon sources.

Install 8kWp of solar panel on your roof (£5k), add a battery (£3k) and AC (£3k)

Charge the battery from the solar and it powers the AC in the evening.

You'll generate more than enough during the day to run AC and fill the battery to run it overnight.

Still using grid sources in winter, but you aren't using the AC. Although you might find air-air AC in heat mode is better than your gas boiler.

More or less the only people who can do that in Europe are rich people with detached homes in the suburbs, which is a vanishingly small minority. European governments could do a lot more to invest in photovoltaics, but it's a bit complicated with how cramped the continent is.

You can replace farmland, but that seems like a really bad idea with Globalism's decline. Who knows what's going to happen to the food supply chain over the next 30 years. The only other option is attaching them to the exterior of historic buildings, and heaven forbid! Think about the character of the neighborhood!

Plenty of semis and terraces have solar. Including the semis I can see out the window right now.

In the UK Semi, Terrace and Detached is about 75% of households and 80% of people.

If you look only at owners it's about 90% of households (and even higher for population)

And anyone who owns a home is rich. If you can afford 300k for a house you can afford 15k on reducing your electric bill.

Now rental of course is a separate matter, and the real problem.

As housing is so constrained landlords can extract all the money from tenants regardless of the quality, but even if it isn't, renters tend not to value things like solar or aircon. You can spend £10k adding solar to a house, but you probably aren't going to get enough from extra rent to offset the cost of installing it.

In the US a property owner has to provide AC because renters will expect it, same as you have to provide a washing machine connection in a rented place. This is a mindset thing which can't be changed.

In other European countries, but its not changing. Among owner-occupiers its France 80% houses, Germany and Austria 70%.

However the rental issue is far more in those countries, where nearly half the country live in rental. Things like balcony solar work well there, and they can power a portable AC.

Normally with ground heat exchange you cool down the hole so the system becomes less efficient over time. With cooling of your house that extra heat goes down the hole again. That ends up being almost free over the lifetime of the entire system.

Run on solar (sun usually shines when it's hot) and use geothermic energy. The ground below your house is significantly cooler than the surrounding air.

I'd still favour the fan, I've lived in India for longer periods with consistently around 32-36 C and a fan is perfectly enough after a little while of adapting.

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