I've noticed that using misters, or just spraying down the floor on really hot days can cool it up to 5 to 10 degrees. I can't use misters because my hard well water turns all my plants white with mineral deposits, but I do spray the paver floors.
I'm sure you can find a small AC unit, or even a heat/cool one, but it sure would be expensive to run....but what's a bit more when it's already a big money pit?
I've found we'll do about anything to have happy plants!
