Here's ours, started last summer.

http://miscellaneouspics.webs.com/

It's 18 x 33'. We used plastic barrels filled with water to help regulate the temps during winter. This was our first winter with the greenhouse, but I do think the barrels helped with the temps, which get down to 0 or below often.

Brendasue

Wow! That is a large greenhouse. You had to use a backhoe and all.

Glad to here about the rain barrels.

What about cooling? Do you do anything special?

Tey

We finished it last September so havn't gone through a summer with it yet. We've inquired about a shadecloth, but we are going to hold off for now. I don't think we'll be able to use it when it starts getting hotter unless we use install a mister-not worth the money to us as we're not getting any returns (personal use).
We have a large exhaust fan & automatic vents-it gets in the 90's * 100's on a 60 degree day without the fan. It is true though-you gain a whole month or more -we picked our first strawberries last week, normally it's the end of May.

On the southern wall, the concrete blocks the sun maybe 3 feet up, and there is a little v-like nook that stays cool. I think it's a combination of the blocks & the clay floor. Anyways I'm thinking I may be able to grow spinach or something shallow-rooted that will remain in that shaded nook. It would be neat to have spinach growing in mid summer!
Brendasue

Thanks Brendasue, for answering so many questions.

I've decided to go with a Rion greenhouse. I'm excited, but thinking I need a shade cloth.

tey,

Shade cloth + mist + exhaust will keep me about outside temp generally. You can go under with certain misters or evap cooler.

Ours is 11 x 16. We tried putting our 65-gallon black rain barrel filled w/water in the GH for winter. We monitored it for about 3 months and noticed no difference in temperature patters when we removed it so I doubt we'll waste the space again. It just doesnt seem to work in any appreciable manner-- even when the black barrel took full sun most of the day, it was cool long before the GH needed aditional warmth later that night.

Thanks fuzzymoto!

your mileage may vary but it didn't work at all for me and I've read many similar posts on here with the same experience.

After reading the follow up posts I just wanted to add a couple additional comments-maybe others will get some ideas for themselves.

We fixed the wasted space issue by cutting barrels at the 3/4 mark. The larger part became a barrel for unused soil (& a non-related hayfeeder), the top 1/4 became planters, which we placed on top of barrels filled with water. The result: strawberries starting April 11th. Sure, we probably would have gotten strawberries within that time frame anyways, however I do not feel the space was wasted (for our purposes). Oh, and by setting the planters up like we did, the chipmunk that stole my planted corn seeds wasn't able to access my strawberries. For us, it worked very well.

Those water barrels by no means heated the greenhouse, but I do feel that they kept the temps higher than if they weren't utilized.

Brendasue