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Greenhouse humidity control | Avoid excessive humidity
Written by Eef Zwinkels | Last update 18-04-2020
Greenhouse humidity control helps you prevent a humid climate. A humid climate with excessive humidity leads to various cultivation problems, such as inequality and the onset of diseases in your crop. Therefore it’s important to control the humidity by dehumidifying your greenhouse air. Dehumidifying the greenhouse can reduce the humidity supply or increase the humidity output. In this article, our specialist explains how to control humidity level in greenhouse.
Determine humidity
To determine what the extent humidity is in the greenhouse, you should first know what the air humidity is in the greenhouse. The best way to measure the humidity in a greenhouse is to look at the absolute humidity. This indicates the amount of humiditythe greenhouse air contains, expressed as the number of grams per m³ of air (g / m3), or the number of grams per kilogram of air (g / kg). If you know what the humidity is in the greenhouse, you can determine if this is too much and if so, how to dehumidify.
Reduce humidity consumption
The more a crop evaporates, the higher the humidity supply, the higher the humidity in the greenhouse. Evaporation is of course important for the absorption of minerals, but excessive evaporation causes excessive humidity in the greenhouse. Water will begin to appear on ceilings or the plant themselves. This can cause diseases such as downy mildew, botrytis, alternaria and more.
Traditional greenhouse humidity control
Therefore, to reduce the humidity supply, you can choose to heat less or to open the greenhouse. This reduces the evaporation and the output of humidity. However, in many cases this will result in high energy costs. Please note: with this method you need to be aware that the evaporation doesn’t fall below the minimum, too little humidity is just as damaging as too much humidity!
Video: DryGair
Besided reducing the humidity consumption, there are also methodes to remove excessive humidity in the greenhouse is to increase the humidity output. When you have a screen cloth, also called greenhouse curtains, it will drain the humidity, which will condense against the cold roof. However in many cases this method doesn’t provide enough humidity removal. By creating a small gap in the screen the drain can be increased. The disadvantage of this method is that there’ll be a local cold trap.
Some growers choose to use greenhouse fans, instead of creating screen gaps. However, this causes problems as well. The windows have to be opened more often. This causes heat loss and thus a higher energy consumption. On top of that, it can also create a lack of climate uniformity.
Reduce humidity with DryGair units
However, there is an alternative for greenhouse humidity control - greenhouse dehumidifiers. This unit pulls moist greenhouse air through the installation, where the air gets heated and dried. The dry, warm air is then reinserted in the greenhouse and the extracted humidity can be reused. The advantage of this is that no energy is wasted: the used electrical energy and the released heat both come back in the greenhouse and the water is suitable as process water. On top of that, the unit also creates air circulation resulting in uniform conditions throughout the greenhouse.