https://www.youtube.com/watch?v=ZD_3_gsgsnkThese guys are using recessed greenhouses in combination with geothermal heat. They have pipes buried around the property and active air circulation system. In summer the cool air is pumped from underground, in the winter the same air is above freezing, keeping plants alive.
Greenhouse being partially underground means it has improved heat/cold buffer as opposed to it being fully above ground.
What they do as well is position the greenhouse perpendicular to where the sun is most of the year, and place a reflector wall on the opposite side to increase the amount of light the plants get.
This shit has any point in places that get quite cold in winter but have a ton of light at the same time, so most of the northern US, parts of continental Russia/China and the like. Europe is either warm enough for most of the year already to not need this (sans the cooling maybe), or places that get too cold to grow plants don't get enough sunlight due to them being way north anyway.
There are some places way up north like Iceland where they have geothermally heated greenhouses, but they also use supplemental light, electricity for which is also generated by using geo heat.
