No it just sits on the ground. I went down a whole rabbit hole recently about how to keep a greenhouse warm in winter. Being below ground would probably help

No it just sits on the ground. I went down a whole rabbit hole recently about how to keep a greenhouse warm in winter. Being below ground would probably help somewhat. A lot of people do something like this- https://ceresgs.com/environmental-controls/gaht/ https://ceresgs.com/environmental-controls/gaht/ I did the math and used a kill a watt to monitor the usage and just doing a little space heater hooked to an Inkbird temperature controller was plenty economical for me. I have cheap electricity where I live though. About 30 cents a night when it is freezing outside. So absolutely worst case scenario would be $9 a month which I can handle for how much joy it gives me to be able to grow plants in the winter.