Ive thought of the winter as well. I live in the carolinas, so right now my AC has been going non stop all summer. What I thought of doing was placing a manual valve on my air handler so I could have no AC in the main house when its cool and just AC in the grow if needed. Today is the first day its not hiting 90 and should be in the 70's for awhile, THANK GOD. This has been the worst summer! And I have been waiting for it to cool down so I can get to building up there. I even thought about getting the grow room its own system. You can get units just like in hotels that can be for heating and cooling. To be honest, I dont know what the best way is going to be yet. I guess I'm just going to do some trial and error and see what works. Thats the only thing that sucks about the south, no body builds basements if you dont have too. I grew up in PA, and just about every house has a basement. Thats why I was hoping I could get with someone on here that have ventured in the attic and had some pointers. It sucks that its my only option. Thanks for your thoughts.