Guys! The OP lives in Anchorage Alaska! I don't think a green-house - with some good ventilation - would be too hot in the short Alaskan summer. I would be more worried about tbeing too cold in winter. PolyCarbonate is not a good insulator, you might have to cover some of the surfaces with styrofoam.
I did see the location.
Here in balmy Colorado my car will heat to well above 50° when outside temps are in the low teens so long as the sun is shining.
