there is another option, it depends on your geo stratification. I am getting engineering started this September for a smart system greenhouse heating and chilling system. the cold can be pumped into a layer of sand with clay then extracted in form of chilled water using mixed power source (for us micro hydro+ wind+ solar) we have a layer of sand 7+ meter thick 20 meters down. it is sort of like geo mass with a heat pump but so much more, in a zone 3 temp wise i will be able to have a tropical green house for citrus and other warm climate edibles. The green house is only half green house other half is closed heavily insulated structure, angling to catch sun can change the temperate zones inside a green house.
It is a proven technology http://groundswellnetwork.ca/ is a smaller working model with no cold pump, using the same engineering company to model 4 more different types of greenhouse to be able to produce all year using part of the heated building for my bee colonies. It will allow me to produce fresh produce all year and sell it locally, including some exotics by next year.