Attached lean-to greenhouse cooling

14 years ago

Hello. I recently started using a greenhouse on my university campus for growing plants and vegetables. It was constructed in the 1970s, and used as a plant lab until several years ago. I'm still learning the ins and outs of things. What type of shade cloth, and density, should I use to cool the greenhouse? There's a ridge vent and side vent, but they are placed beyond arm's reach. What type of fan should I use to cool the building, which is 32 ft by 18 ft, and about 13 feet tall where attached?

This is urgent, because it recently reached 115 F relative temperature inside, and that's only in June.

Thanks,

Yosef

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Comments (4)

calliope
14 years ago
I don't understand what you mean by the ridge and side vents being out of reach. Surely they were functional at one time. I have fan cooled g'houses except one, and it has a roll-up side assembly. A friend has ridge vents on his g'houses and he says he's very pleased with their performance and find them totally adequate for his vent needs and he doesn't have the electric bills I do in summer.

I have Acme wind fans in my houses........mounted through the wall and am very pleased with them. A couple of them are on their twentieth year and still cranking, and automated louvers on the opposing walls all on stats. The most common mistake most people make in their fans needs is underestimating their sizes. A fan should be able to pull out and exchange the air in a g'house in a matter of minutes, totally. This means, on a house that size, that you could probably call any of the major manufacturers and they'll help you out on sizing one for your needs.

However, I am not in your climate zone. I run forty percent shade on my summer houses and it still can get up to over a hundred on hot, sunny days. What are you growing in the dead of summer?
ykerzner
Original Author
14 years ago
The side vent is on the other side of 6-foot-side benches, and the ridge vent is only accessible via a manual pulley (and is half broken).
How big are your Acme wind fans? There are two store-bought fans in my greenhouse, each about 24 inches wide. There are roughly 5500 cubic feet of air inside.
Some of my tomato plants are still setting and fruiting. I grow eggplants, peppers, tomatoes, and some tropicals.
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calliope
14 years ago
I'm still trying to wrap my mind around how the g'house is set up. If you can't reach the side vents, and the top vent isn't operable, is outside air coming in through any opening? It needs to be intaking. You won't get much cooling if your fans are just circulating inside air around. Even when I don't have fans running, with the louvers slaved to them, I have manual vents I can drop. Sometimes I use them for passive ventilation when I don't want the big fans sucking air over my plants, like when it's a bright, but cold day in mid-winter. I can't see how you could even work in an unvented g'house in summer in Texas. Whoa.

Your cheapest and easiest option would be to fix the ridge vent, and move the benching enough to access the side vent. My wind fans are all different sizes, and the big selling house has dual fans and all my houses have venting for air intake clear across the back. You can't compare your g'house to mine for fan sizes. You can calculate the rating of the fan you need by figuring out the volume of air in the g'house in cubic feet, and then find a fan rated to move that in a minute and a half. Then you need to calculate how large an opening on the opposite side of the g'house you'll need for air intake. If it's not large enough, your fans will not work to capacity and you can burn them up.
ykerzner
Original Author
14 years ago
The greenhouse is like this:
____________________________________________
IF six foot wide benches................. I ^side vent
IA I 8 ft
IN I height
I ______ I
I I I I
I I I I
I I I I
I I I I
I___________________________I______I________I

Ridge vent at this end, 12 feet up

Attached to Building at this end and left end.

Dimensions: 32 feet long, 18 feet wide.
There's no opening on the side that faces out. Roughly 5400 cubic ft.

I know the diagram is not good.
As a matter of fact, after reading today about HAF, I repositioned one fan to blow at the side vent, so that air comes out. Not sure if that will help.

Attached lean-to greenhouse cooling

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calliope

ykerzner
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Attached lean-to greenhouse cooling

Comments (4)

calliope

ykerznerOriginal Author

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calliope

ykerznerOriginal Author

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ykerzner
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