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This week I went to an event where they had this amazing machine that demonstrated the workings of a heat pump: taking a unit of heat from the right side and transferring it to the left side, the beers are cooled and the (vegan) sausages are warmed. I think it's brilliant and should be used to overcome any doubts or resistance to heat pumps, especially in Germany. Maybe they should be mandatory in every beer hall?
@ddrake@mathstodon.xyz(tl;dr we replaced our natural-gas-only furnace with a dual-fuel gas and heat pump one and it's great.)
On the subject of heat pumps and mathematical modeling: in summer 2022, I got a heat pump furnace/air conditioning unit. Here in #Wisconsin it gets very cold in winter, so the furnace needs to be dual-fuel: both a heat pump and natural gas.
We were replacing a natural gas furnace, so I wasn't expecting any large difference between the old furnace and the new one when using gas. So I wanted to compare energy usage between situations when the old furnace would be running (using gas) and when the new one would be using the heat pump.
I have an Ecobee smart thermostat, and you can download all your usage and temperature data in CSV format. I used that to estimate that the heat pump would replace about one third of our gas usage. I made a nice #Sagemath notebook and everything. :)
That was summer 2022. I then tracked our gas usage last winter -- and was pleased to find my estimate was right!
Yay for data and modeling and heat pumps...
@ddrake @burger_jaap I live in silicon valley, California (mild weather all year) and the 1950s gas furnace is ~50% efficient at turning natural gas into warm house (the rest goes up the flue/chimney). 6 months of 2022 we used 15 therms/mo for hot water, cooking, and clothes drying. The other 6 months add in space heating, raising that to 37 therms/mo. My estimate is that we would save $200/yr with a heat pump ($4.27/therm, $0.12/kwh). Your climate and energy price will vary! PV changes the math
@trouble @burger_jaap looking briefly at my data: the year before our new furnace, during the heating season we consumed 534 therms; the first heating season with the new furnace, 331! (I didn't account for any temperature differences, but the two years were roughly similar.)
And we do have solar panels. During the summer, they generate nearly as much as we consume.