This is an interesting study about the efficiency of two kinds of evaporative greenhouse cooling designs for non-hermetic (unsealed) greenhouses like they use in Spain to cultivate vegetables and flowers extensively. It seems like more efficient than the big evaporation pads are these cooling boxes that look like they could get found used at industrial salvage or maybe DIYed pretty easy, basically the fan to the inside draws hot air through a honeycomb type matrix of plastic that has drippers running down through it and it’s far more effective:
As others have mentioned without low humidity the swamp coolers and misters loose a lot of their efficiency. If you are in an area with large humidity and temperature swings you will really want a more advanced system that will determine whether or not the misters come on depending on the temp/humidity/light schedule, otherwise you are just asking for large humidity swings and mold. If you are in an area with constant medium to high humidity, you really just want to make sure you have enough air exchange through the greenhouse with larger intake and exhaust fans to keep it cool.
If you are really set on the misting send me a DM and I can explain a little more of what’s required.
Well I already did the misters and kinda abandoning it to a point. I installed a swamp cooler this weekend and while it doesn’t seem to be the answer to all my issues, it’s doing pretty good right now. I’m going to leave the misters installed. I’m mostly looking for an improvement over last year, where I had very low humidity and very high temps, like 105-110F for a few hours. Even with those extremes I did pretty good.
You could still use the misters to add humidity via a small humidistat like an inkbird, just try to keep the misters from directly spraying the plants.
Yeah I have an ink bird temp controller, should probably get a humidity one. In my set up the misters were in the non-plant half, but the fans blew some on the plants and would run way too long, leaving a TON of water all over… not good. Lol
I fabricated a swamp cooler type set up I guess it could be called. It was for a buddy down the road that has an artesian well on his property that they have piped and plumbed for thier household water. It also has an overflow that forms a small creek on the property so there is lots of water on hand. He installed a seperate jet pump and plumbed it to the greenhouse where it splits into 2 large truck radiators with a 20" blade box fan between them, mounted in a sheet metal box frame. The outflow from the radiators is plumbed to a hose that fills 3 x 100 gallon water tanks he uses to water his garden and then overflows back to the creek. The water supply is on solenoid control that is ran by an inkbird temperature controller.
It’s a genius set up and even in last years low 40C heat wave, his greenhouse was holding at 26C. Gotta have a cold water supply to make it work though.
