跳至内容 
Greenhouse Ventilation Systems
Ventilation removes heat and humid air and brings in fresh air. A commercial greenhouse uses roof and side vents, fans, or a mix of both. FANGCHENG designs and supplies the vents, drives and controls for your climate and crop.
Why greenhouses need ventilation
Remove heat on sunny days
Release humid air, which lowers disease pressure
Bring in fresh air with carbon dioxide for the plants
Even out temperature from one end of the house to the other
Natural, mechanical or hybrid
Wind and rising warm air.
Exhaust fans and circulation fans.
Uses little energy.
Uses power, so it works in still, hot weather.
Depends on the weather.
Works whatever the wind does.
Roof vents, sidewall vents, roll-up sidewalls and louvered openings.
Fans, inlets and controls.
Tap a side, or the photo, to compare.
Hybrid
Natural vents in mild seasons, fans in hot or humid periods, and reduced ventilation in winter with minimum air exchange kept.
How natural ventilation works
Two forces drive it.
Wind across the roof
Wind blowing across the roof pulls air out of the ridge opening.
Warm air rises
Warm air rises, leaving through the top while cooler air enters low.
Hot, still days
Wind usually does most of the work. On hot, still days the second effect weakens, because inside and outside are almost the same temperature.
Taller houses
Taller houses use rising warm air more effectively.
Roof vents and side vents
Roof vents.
Let hot air out at the top of the house.
Side vents.
Let cooler air in at the sides.
Placement.
Vent area and position are set from floor area, house height, wind direction and climate. Taller houses ventilate more easily because warm air rises.
Ridge and sidewall openings work together
Air needs a way in and a way out. Sidewall openings let it enter, ridge openings let it leave, and the two should be matched. The house is best placed so the usual summer wind crosses the ridge.
Air in low, out highVent designs in plain terms
Ridge vent.
A continuous opening along the top of the house for warm air to leave.
Sidewall vent.
An opening along the side for fresh air to enter.
Roll-up sidewall.
Film that rolls up to open a large part of the wall, common in tunnels.
Louvered opening.
Adjustable slats used at fans and inlets.
Drives and accessories
- Rack-and-pinion drives, gearboxes and motors
- Pull rods
- Insect screens
- Shutters and louvers
- Wind-resistant vent structures
- Controllers that open vents from temperature and wind readings
How vents are driven
Vents can be opened by hand, by a crank, or by a motor with a rack-and-pinion drive and gearbox. Motors give you automatic control from temperature and wind readings. Manual vents depend on someone being there at the right time.
By hand, by crank or by motorProtecting the house from wind and rain
When natural ventilation is not enough
- Very wide or large gutter-connected houses, where air cannot cross the whole width
- Hot, still weather with little wind
- Crops that need tight humidity control
- Houses with insect screens on every opening
Screens, crops and seasons
Insect screens and airflow
Insect screens keep pests out but slow the air. A screened opening has to be larger to pass the same air as an open one. Plan screens and vent size together.
What the crop needs
Crops differ. Leafy greens call for frequent air exchange, flowers for gentle airflow, and seedlings for mild airflow with low humidity. We set the ventilation plan from your crop list.
Ventilation in winter
Heated greenhouses still need some air exchange, because trapped humid air causes condensation and disease. The aim is the minimum ventilation that keeps humidity in check without wasting heat.
Ventilation and carbon dioxide
Plants take in carbon dioxide from the air. A closed greenhouse in strong light can use it faster than it enters, so air exchange helps growth as well as temperature. Where CO2 is added, vents and injection are coordinated so the gas is not blown away.
Air carries CO2 to the leavesKeeping it working
- 01
Keep vents, shutters and fan housings clean
- 02
Check belts, bearings and fan blades
- 03
Calibrate sensors from time to time
- 04
Adjust settings by season
Common ventilation mistakes
Openings that are too small for the house
Vents only on the sides, or only on the roof
Screens added later without enlarging the openings
Vents closed in winter, so humidity builds up
Manual vents that are not opened in time
Common questions
Straight answers. If yours is not here, ask us.
It depends on climate, house size and crop. We size vent area from your conditions. Send us your details.
Roof vents are usually more effective because they release hot air at the top, and most houses use both. We design the mix for your site.
In large gutter-connected houses, fans are usually needed for reliable cooling in hot weather. Tell us your house size and climate.
The openings may be too small, the wind may be weak or the sun load may be too high. Shading, larger openings or fans can fix it.
In commercial production, usually yes. Automatic vents respond to temperature and wind, which saves labor and protects the crop on days when no one is on site.
Run them in step. Climate control opens vents only as far as needed while heat is on.
Roll-up sides are simple and cheap for tunnels. Rigid vents suit multi-span houses and give tighter weather protection.
Yes, through climate control with outdoor sensors.
Explore other systems
Plan your ventilation
Send your location, crop and greenhouse type. We reply within 24 hours.
Consultation and project proposals are free.
What to include
- Location
- Crop
- Greenhouse size
