I want to put a fan to move cooler air into the greenhouse

[Guest]

Is it best to put a fan at the bottom of the nouth wall pulling in, or high in the wall south pushing air out?

[Andy]

Firefighters have been moving smoke out of buildings for many decades. We used to use "smoke ejectors" which were put in a window and meant to suck smoke out of the building. But studies of air movement physics taught us that it's better to pressurize a building to move as much air as possible. So, we switched to large fans that are usually placed at an exterior door blowing in.

With the building pressurized you can select which window to open, and thus what path the air takes.

The most efficient way to move hot air out of a building would be to place the fan low, on the coolest side of the building (normally north for a greenhouse), and have the opening on the opposite end, high up.

[Owensboro]

Common practice is to have an exhaust fan at the top end of a greenhouse and louver/louvers in the opposite end near the bottom.

This exhausts the hot air near the peak and draws in cooler fresh air from the opposite end.

Another common practice is to have mounted fans inside the greenhouse to push even more air if needed and causes air to circulate better.

I take my greenhouse panels off in the summer and drape the frame with shade clothe. This allows me to have a shade structure. Summer growing in a greenhouse can be very difficult due to the high levels of heat. Many people don't use their greenhouse in the summer because plants can thrive outdoors.

[Dale]

Bring air in from the low side facing your prevailing wind and exhaust out the roof or as high as possible on the opposite end. Trying to exhaust into the prevailing wind is counter productive. Also remember this will not cool the greenhouse below the outside temperature.

[Jeremy]

On the gable ends, fan mounted high on one end.
Louvers mounted low on opposite end.
Double the louver size versus fan.