What you have described is geothermal heating, only using less total energy due to not having to heat for human survival. This tech is also used on buildings t

What you have described is geothermal heating, only using less total energy due to not having to heat for human survival. This tech is also used on buildings to keep from frost heaving. https://canada.constructconnect.com/joc/news/technology/2016/09/thermosyphons-use-simple-physics-to-lick-cold-climate-challenges-1018682w https://canada.constructconnect.com/joc/news/technology/2016... It's not that big of a deal, consider the thermal difference between the ground and air. Also, consider it is not using any input energy to do it, simply the evaporation of ammonia!