[Cynthia, Prescott, AZ]

Kelly, percent sun, transmission, may be standard for the double and triple walled poly. It is just the shade cloth that I know is percent shade.

Nothing beats an evaporative cooler in summer, in fact, I run mine all year in spite of going down to 10F. I replace the batting and water in spring, and by fall/winter, the water is saturated with minerals, and acts as anti-freeze. When it starts getting cold, I throw a cooler cover over the evaporative cooler, and pull a corner back on mild days. Since I spend a lot of time in my GH, I can 'feel' the need to adjust the cooler cover. I buy a 2 stage thermostat to run the 2 stages of my cooler motor, and hard wire it into the GH.

I recently bought a solar powered vent fan to install in the eve of the GH from Harbor Freight, since I usually baffle the vents in winter, leaving open the possibility of it getting too hot in the GH. Last winter a killed a few plants, operator error, having the cooler off for 2 days in January, or there abouts. Haven't installed it yet.

You never want to put the shade cloth inside the GH, as you will at least double your heat load on what ever system you use to cool your GH. Having said that, I do have extra shade cloth inside the GH where my Phals are to give them the lower light they need. But the outside shade cloth takes out most of the heat. On my old redwood and glass GH, I just had the cloth laying on the structure, with slats of similarly stained wood holding it down. Actually, I stapled the cloth to the underside of the slats, then used some studs in the GH ribbing facing up to slide the strips with appropriate holes over the studs and held them down with wing nuts. But, not much clearance between shade cloth and glass. I viewed it as OK in southern California, but would never be acceptable in Phoenix, where the max 20F drop in temp the cooler is capable of is just not enough when the day temps reach 125F to 130F.

Currently I just throw the shade cloth over my temporary GH, and just hold it in place at the corners.