How to make a greenhouse work in Zone 7B

Has anyone used a greenhouse all year in a Zone 7B?  I am wondering if shade cloth. venting and heating is all I would need or should I go further and look at ground heating/cooling?  I get around 5 to6 hours of sun in this location.

I have a high water table but also a lot of boulders just below the surface (2 to 3 feet).  Summers are brutal June through August and there is a short winter where a couple of weeks it gets around 20F or lower.

I am willing to spend a couple thousand to build something that will last and maybe keep insects out and am looking for innovations.  Air to water heat exchange or other?

How to make this work?

Thanks
Dennis

Hi Dennis, I'm guessing many people have greenhouses in your climate.  I saw a tropical greenhouse on youtube in Texas that seemed pretty simple (from a mechanical systems perspective).  I guess the biggest question is how warm do you want it on your coldest night and how warm do you want it on your hottest/sunniest day?  That could help generate some ideas.  If all you need is 33 degrees on the coldest night, I'm guessing some thermal mass and a double inflated poly hoop house would do the trick.

Keeping insects out could be trickier.  My greenhouse vents in the summer so the bugs come and go as they please.  

I think shade cloth plus moving air (natural breezes or fan) should keep it reasonably cool in summer. Am in 7a and have a neighbor who keeps a greenhouse with a fan that way - have been in it and it is bearable.