Plus at least one thermostatically activated vent fan (at peak on the N wall? W wall? E wall?)
if you are venting, don't forget air intake. Put it the coolest place you can, as low as you can. Output fan at the highest peak in the building, wherever that is. If you have a lot of high peak, do both ends.
If you actually freeze (not sure of your climate) insulating the ground a couple of feet down keeps the frozen outside ground temp out.
Sun angle: 30 is probably fine. You want as much as you can get in spring and fall, summer will be a LOT of excess gain at best.
If you are doing metal and planning it to go underground, waterproof it. Those carports WILL rust out. Takes them a while, but dirt contact will accelerate it.
Something to take into account is water flow across the land, both above and below ground, above ground will flood your greenhouse out, below will possibly affect your plants and moisture issues.
MAKE SURE IT'S ANCHORED DOWN HARD!!!
Swamp cooler adds moisture, take that into account. If you want fans for air flow, input as close to ground as you can get for coolness, output as high as you can. If you run forced air at the bottom you don't need the top to have fans, unless you want them to run separate too.
Should my non-glazed area at the top of the roof be more than 6'? Less? I don't want to be dragging shade cloth around the structure's roof during the July-Aug heat wave next year ...
Do you really WANT much glazed area on the roof? Lets in more heat in summer, lets out more heat in winter. And you definitely WILL end up doing shade cloth if you do that. You might think on that hard.
Without a sketch it's hard to guess what your building angles are, so on the unglazed part of the roof I'd worry most about making sure the peak, wherever it is, is DEFINITELY waterproofed WELL. And waterproofed where it hits the glazing.
Double wall polycarb rocks, BUT be sure it's installed horizontally, it works like a solar chimney making air flow up it's tubes if you don't. Great in the summer, problematic in winter, depending on where it manages to find an air gap to pull in air as it moves heat up.
You also might consider thermal mass in there, as well as reflective surfaces, depending on how you are doing things.
I assume the North wall is totally unglazed? Depending on your climate heavy insulation on that wall may be wise.
:D
