Greenhouse Air Circulation
Greenhouse circulation fans move air inside the structure so temperature and humidity stay more even from end to end and from canopy to gutter. They do not replace exhaust fans; they complement exhaust and pad systems by reducing hot and cold spots.
How it works in a greenhouse
- Horizontal-flow fans move air along the length of the greenhouse above the crop.
- They remix indoor air so temperature and humidity stay more even from end to end.
- They complement — they do not replace — exhaust fans and pad-and-fan cooling.
Applications
- Vegetable, ornamental and nursery greenhouses that need gentle continuous air movement.
- Houses with heating or CO₂ enrichment where even distribution matters.
- Layouts where hot or humid pockets form between bays or at the canopy.
Selection notes
- Share bay width, gutter height, crop height and hanging obstacles.
- We suggest fan count and spacing for a light, continuous breeze rather than a strong draft.
- Most models work with on/off or variable-speed control from a climate computer or thermostat.
Related resources
How Exhaust Fans Work
Pad-and-Fan Cooling
Greenhouse Circulation Fans
Frequently asked questions
Where should circulation fans be mounted?
Usually along the length of the greenhouse above the crop, aimed to create a gentle horizontal loop. Exact height and spacing depend on bay width, gutter height and hanging obstacles.
Do I still need exhaust fans if I have circulation fans?
Yes for summer cooling. Circulation fans remix indoor air; exhaust fans exchange indoor air with outdoor air. Pad-and-fan cooling requires exhaust capacity sized to the greenhouse.
What air speed is typical above the crop?
Many vegetable and ornamental greenhouses aim for a light, continuous breeze rather than a strong draft. We set target speed from crop type and leaf wetness risk when we size the fan count.