@Appelmoesje @givenup The partially underground building technique makes a ton of sense to me. It's geothermal in a nutshell. I think it would make sense to use closed loop heat pump systems for a small scale geothermal directly below the house (under the basement) and I often wonder why this isn't done at building. Seems it wouldn't cost a ton more to just dig another foot or two down and drop a few coils of PEX full of alcohol in water solution, another foot or two of dirt and then normal foundation or French drain work.