Backyard greenhouse

[Ray]

Originally Posted by Selmo

In the summer we opened the doors at each end and placed a fan in each doorway and blew air through the house.

I recommend you take a somewhat different approach.

Install shutters in one end, and make sure they are covered with window screen to block the entry of insects. I have mine automated with solar-powered vent openers, so they open as the greenhouse warms to allow some passive ventilation.

In the opposite end of the greenhouse, you could install a swamp cooler to push the warm air out and blow cooler, humidified air in. I only have an exhaust fan in the rear, pulling the air in through the shutters. That fan shutter is screened, as well.