@Thomas75, I don't know why your post does not show you are a new ATP member, but regardless,
I have owned greenhouses for almost four decades, from a really grand 15'x32' one, a 3' skirt built of brick, marine aluminum framing, and glass (two hurricanes finally took that one away). I now have two, 10x12', BIY ones. I have these two with 60% and 75% shade cloth (one gets more afternoon sun), multiple fans, and vents and doors wide open. About the only thing I can use those greenhouse for in the summer is to grow succulents, root plumeria, and start seeds. It is not unusual for those greenhouses to get110-120F when the ambient temperature is 90F. We are often in the mid to upper 90's and two summers ago, we had a string of two weeks with temperatures above 100F. The only way I could lower that temperature would be to install swamp coolers or AC, or have full afternoon shading via dense trees.
