the parent was not talking about geothermal, but storage which would come as interesting to store winter cold for the summer, I have no idea whether it would work.
Based on some guesses and uninformed searches if a house spends 200MJ on cooling and there is a 20 C delta between winter temperatures and desired cooling temperature and assuming a specific heat capacity of ~800 J/(kg*K) you would need 12.5 tons of rock as battery which would be around 6~8 m³ which sound very small.
I am sure that there are hundreds of complex factors at plays (eg rain water and aquifers reheating the battery during spring) but it came out to be a far smaller number than I would have guessed.
Based on some guesses and uninformed searches if a house spends 200MJ on cooling and there is a 20 C delta between winter temperatures and desired cooling temperature and assuming a specific heat capacity of ~800 J/(kg*K) you would need 12.5 tons of rock as battery which would be around 6~8 m³ which sound very small.
I am sure that there are hundreds of complex factors at plays (eg rain water and aquifers reheating the battery during spring) but it came out to be a far smaller number than I would have guessed.