Greenhouse vents and ventilation.

Here are many examples of greenhouse vents and how they work.
I hope one of these can solve your ventilation problem.
If you live in a mild west coast area, little frost, cool summers, then a passive vent made out of shade cloth might be enough.

Greenhouse side vent made of 2x2 cedar and polycarbonate with a gigavent. - grid24_12

Then we found these solar vents. (The little ones on the left.) which led to the one on the right.

Turbine vent on top of one of he greenhouses, it didn't work all that hot but this greenhouse had real problems. Too low and the wind could not get to it. A humid desert, if you watered much the moisture never left. - grid24_12

We even tried a turbine vent, but with our heat, forget it!

These small solar vents can't be used on bigger vents as they can only open a kg. or so. - grid24_12

We tried being cheap and using a small wax windo opener, the wind ripped it off and it wouldn't open much.

If you use small vents they will only work in cool climates, small greenhouses, and only if jammed to the top of the sides. - grid24_12

Here are more of the first vents we tried. They work ok for small greenhouses.

Then we started getting serious.

One of the greenhouse end walls with vents open. This solved most of our ventilation problems. That and keeping the greenhouse to 50 ft. instead of 100. Discovering you only have to carry plants 25 ft instead of 50 ft. also helped.

top vent of a polycarbonate greenhouse - grid24_12

Top vent of a polycarbonate greenhouse at an air temperature of about 90F.
The higher you can get the 'out' vent the better it will work, unless you have regular wind, then it needs to go high on the leeward end.

Outside of greenhouse looking at top vent. The higher you can get the 'out' vent the better it will work, unless you have regular wind, then it needs to go high on the leeward end. - grid24_12

Top vent of polycarbonate greenhouse from inside the greenhouse. - grid24_12

The vent structure from inside the greenhouse.

Two different type of greenhouse end vents - grid24_12

Poly greenhouses are a little trickier, you have to frame the vents.

Large end vent on greenhouse. This end vent is 4 foot tall and 16 feet wide - grid24_12

The end of a small polyethylene greenhouse at about 90F.

Greenhouse sides can be of pvc, polycarbonate, fiberglass or poly. We've found the best was polycarbonate for the first couple of feet. The rest of the greenhouse can be poly. Notice the polycarbonate vent. Greenhouses have to be vented. - grid24_12

With the large solar wax based vent openers you can open the wall. This vent is 8X8 feet. - grid24_12

Passive solar vents at end of greenhouse - grid24_12

polycarbonate end wall with vent - grid24_12

To see more how to build stuff go to our

How to build garden stuff
or
How to build a cheap and easy greenhouse
How to build a simple poly greenhouse.