Climate Control

Greenhouse Ventilation & Cooling

A greenhouse without ventilation cooks the crop. Natural roll-up curtains, exhaust fans and evaporative cooling pads keep the temperature and humidity in the range your plants need, so you can grow through the heat instead of losing to it.

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Interior of a ventilated commercial greenhouse

The basics

Ventilation is climate control

Inside a closed greenhouse the sun pushes the temperature far above the outside air, and the crop breathes out moisture all day. Without a way to move that heat and humidity out, you get heat stress, condensation and disease. Ventilation is how you take control: it swaps hot, damp air for fresh air, and holds the climate in the range where the crop actually grows.

There are three tools, and most greenhouses use a combination. Natural ventilation moves air for free with roll-up curtains and roof vents. Forced ventilation uses exhaust fans to pull air through on demand. Evaporative cooling adds a wet pad wall that drops the incoming air several degrees. We size the right mix for your structure, your crop and your climate.

Where it applies

Gutter-connected greenhouses Gothic greenhouses High tunnels & hoop houses Propagation & nursery Tomato & pepper houses Leafy greens & floriculture

What good ventilation does for the crop

Temperature is only half the story. A well-ventilated greenhouse also controls humidity, disease and air quality.

Controls temperature in peak heat

Removes built-up heat and, with evaporative cooling, drops the incoming air by several degrees.

Lowers humidity, cuts disease

Refreshing the air prevents condensation and excess humidity, the number-one cause of fungus and foliar disease.

Fresh air: more CO2 for photosynthesis

Air exchange replaces the CO2 the plant consumes, which sustains photosynthesis and growth.

Uniform climate across the house

Circulation fans prevent hot spots and humidity pockets, for a uniform crop end to end.

Less stress, more yield

A plant that avoids heat shock sets fruit better and yields more. A stable climate pays for itself at harvest.

Natural ventilation, no energy cost

Roll-up curtains and roof vents ventilate using the wind and rising hot air, with no electricity cost.

The three ways to ventilate

Each method solves a different part of the problem. The best result usually comes from combining them.

Natural ventilation

Roll-up side curtains and roof (ridge) vents that let rising hot air out and fresh air in. The cheapest to operate, ideal for temperate climates. Combines with insect netting to keep pests out.

Forced ventilation (exhaust fans)

Exhaust fans that pull air through the greenhouse on demand, plus circulation (HAF) fans that move air between the plants. Essential when climate or house size make natural airflow alone insufficient.

Evaporative cooling (pad & fan)

A wall of wetted pads at one end and exhaust fans at the other: incoming air passes through the water and cools by several degrees. The most effective way to drop temperature in hot, dry climates.

Gallery

Climate under control

Greenhouse with roll-up side ventilation

Tomato crop in a climate-controlled house

FAQ

Frequently Asked Questions

What type of ventilation does my greenhouse need?

It depends on the climate, the size of the house and the crop. In temperate climates natural ventilation, roll-up curtains and roof vents, is often enough. In hot climates or large houses you usually need forced ventilation with exhaust fans, and in hot, dry climates evaporative cooling with a wet pad wall is the most effective. We size the right combination for your case.

How does evaporative cooling work?

A wall of water-wetted pads is installed at one end of the greenhouse and exhaust fans at the opposite end. The fans pull outside air through the wet pads; as it passes through the water, the air cools by several degrees before reaching the crop. It is the most effective way to lower temperature in hot, low-humidity areas.

Does ventilation help against disease?

A lot. Excess humidity and condensation on the leaves are the main cause of fungus and foliar disease. Refreshing the air lowers relative humidity and dries the environment, which directly reduces disease pressure and the need to apply fungicides.

Can I ventilate without letting pests in?

Yes. The ventilation openings, both the side curtains and the air inlets, are covered with insect netting of the right density. The greenhouse breathes and stays cool, but aphids, whitefly and thrips stay out. It is a very common combination and we recommend it in almost every project.

Do you help design the ventilation system?

Yes. We consider your structure, crop, climate, humidity and house size, and design the system, natural, forced, evaporative or a combination, with the right capacity. We work with the leading manufacturers in the market and support you from design to start-up.

Keep your greenhouse in the right climate

Tell us your structure, your crop and your climate, and we will design and quote the ventilation and cooling system your greenhouse needs.

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Two minutes, three fields

Tell us what you grow and where

That is enough for an advisor to come back with something useful: the structure that fits your climate, what it involves, and what to plan for. No obligation.