This is a roll-around portable cooler, and not appropriate for permanent installation. If your thought is to just roll it into the greenhouse, you will have one of two problems. 1) if you use it in addition to an exhaust fan, the warm dry air you bring into the greenhouse will displace it and negate the cooling. 2) if you use it instead of an exhaust fan, the humidity in the greenhouse will increase, eventually defeating the cooling effect.
The way you should use an evaporative cooler is instead of an exhaust fan, drawing (relatively) dry air from outside, which will be cooled by evaporation and exhausted through a relief opening (hopefully high in the GH). I have no idea about maximum temperatures or temperatures in Saskatchewan, but any GH exhaust system should be designed for a minimum of one air change per minute (fan cfm = GH volume in cf.)
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