i have a pretty amazing crew of volunteers at work, several whom are engineers and take it upon themselves to fix things and come up with solutions to situations. the doors on the smaller hoop house down the street were starting to fall apart, and wonder volunteers dennis and gene took it upon themselves to make new doors. i mentioned off-hand that it would be nice if they were dutch doors, so i could open the top and vent the greenhouse.
this is what it looks like closed
and open. this way on cold sunny days i can get some of the hot air out, without having to open the door fully or rolling up the side vents. this helps keep the plants from getting too much chilly air on them.
construction is pretty simple for the vent, the top door frame has a rabbit going around the edge for the top panel to lay down in, and then a couple of simple clasp to hold it in place. at the bottom is a hinge, which you can see in the top picture, and the whole thing drops down when the clasps are turned up.
pretty great simple design, of course it would be better if we made it out of something that had good light transmittance, but it works well enough.