Ventilation is one of the most important components in a successful greenhouse. If there is no proper ventilation, greenhouses and their growing plants can become prone to problems. The main purposes of ventilation are to regulate the temperature and humidity to the optimal level, and to ensure movement of air and thus prevent build-up of plant pathogens (such as Botrytis cinerea) that prefer still air conditions. Ventilation also ensures a supply of fresh air for photosynthesis and plant respiration, and may enable important pollinators to access the greenhouse crop.
Ventilation can be achieved via use of vents - often controlled automatically via a computer - and recirculation fans.
Improvements to natural ventilation systems result in an increase in production without significant cost compared with other climate control systems. The ventilation capacity of the Almería-type greenhouse must be improved, since it is still currently insufficient despite the improvements in recent years. The average window surface is 14.4%, which is far from the minimum window surface value of 30% that is required for correct ventilation or even the value of 25%, which is recommended in the Regulation for Integrated Production.