Earth Sheltered Greenhouses use the fact that the earth is a stable temperature all year round to greatly extend the growing season. These were known to native people as walipini or “place of warmth”
http://www.inspirationgreen.com/pit-greenhouses.html
There are so many different types of greenhouses and clever adaptations that books upon books have been written on the subject. Has anyone seen really clever designs in action?
The Housing Lab 
I think this is so interesting and I’ve linkked it with my my friends and followers!
Thans for this thought provoking info.