A really cool example of how efficient a house can be built to supply full solar heating. If you cannot watch the full video then at least check out the first 10 min, and at 40 min he gets into his year round garden, which even grows chia :) He is at a Latitude of 40 Deg
https://www.youtube.com/watch?v=T0zaiWJSHSw&feature=autoplay&list=UUnF2pFCQbYgxmqx3imNsTCQ&playnext=1
https://www.youtube.com/watch?v=T0zaiWJSHSw&feature=autoplay&list=UUnF2pFCQbYgxmqx3imNsTCQ&playnext=1