How Exhaust Fans Work
Greenhouse exhaust fans create negative pressure that pulls hot, humid air out of the greenhouse. So cooler outside air can enter through side vents or an evaporative cooling-pad wall.
How it works in a greenhouse
- Wall-mounted exhaust fans pull warm, humid air out of the greenhouse.
- Negative pressure draws cooler outdoor air in through side vents or a cooling-pad wall.
- Used with evaporative pads, this forms a classic pad-and-fan cooling layout for hot weather.
Applications
- Film, glass and polycarbonate greenhouses — single-span or multi-span.
- Summer ventilation and tunnel-style airflow when pads are installed on the opposite end.
- Projects that need matched fans and pads quoted as one climate package.
Selection notes
- Share greenhouse length, width, eave height and location.
- Describe crop type, peak summer goals and whether you already have pads or vents.
- We recommend fan type and count for your air-exchange target, then quote by project.
Related resources
Pad-and-Fan Cooling
Greenhouse Air Circulation
Greenhouse Exhaust Fans
Frequently asked questions
What size exhaust fan do I need for my greenhouse?
Size depends on floor area, eave height, crop heat load and local design temperature. Summer pad-and-fan or tunnel layouts often target about 45–60 air changes per hour. Send length, width, height and location to [email protected] for a model recommendation.
How is an exhaust fan different from a circulation fan?
Exhaust fans remove air from the greenhouse and create negative pressure. Circulation fans move air inside the house to even out temperature and humidity. Most commercial greenhouses need both.
Can ClimaSpan supply a full pad-and-fan package?
Yes. We supply matched exhaust fans, evaporative cooling pads and circulation fans for greenhouse projects and can quote them as one climate package when you want a complete layout.