Dehumidification

• Condensation refers to the formation of drops of water from water vapor.
• Condensation occurs when warm, moist air in a greenhouse comes into contact with a cold surface such as glass, fiberglass, plastic or structural members.
• The air in contact with the cold surface is cooled to the surface temperature.
• If the surface temperature is below the dew point temperature of the air, the vapors in the air will condense onto the surface.
• Condensation is heaviest in greenhouses from sunset to several hours after sunrise.
• During daylight hours, there is sufficient heating from solar radiation to minimize or prevent condensation, except on very cold, cloudy days.
• Greenhouses are most likely to experience heavy condensation at sunrise or shortly before.
• Condensation is a symptom of high humidity and can cause significant problems (e.g. germination of fungal pathogen spores, including Botrytis and powdery mildew.)
• Condensation can be a major problem – at certain times of the year, impossible to avoid entirely.