How Humidity Affects Greenhouse Energy Usage
But humidity control doesn’t have to be so energy intensive. Using a dehumidifier designed for horticulture will extract water from the air with much greater energy efficiency, in terms of liter or gallon per kW.
Additionally, simply monitoring relative humidity levels, or VPD, and your dehumidifier’s extraction rate can help conserve energy. Reduce humidity only when necessary and avoid unnecessary energy expenses.
Traditional Humidity Control Methods Are Inefficient
One of the most common ways greenhouse operators reduce humidity, is by ventilating to let the moisture out.
The problem with ventilation is that it requires an exchange of air with the outdoors, making weather much more impactful in affecting the conditions inside the greenhouse.
If conditions outside are humid, it may fail to reduce humidity inside. But more importantly, when it’s cold outside, ventilation will cause greenhouse temperatures to drop.
That’s the biggest issue with ventilation. It creates a vicious cycle in which growers heat, to provide comfortable temperatures for the plants, and lose heat, through ventilation, requiring more heating. That’s a lot of energy just to maintain the same temperature.
That doesn’t mean growers shouldn’t ventilate. It’s a great way to reduce humidity levels when conditions allow it. But during the night, or when it’s raining, or cold outside, ventilation isn’t as effective, and is much less efficient.
Using Dehumidifiers to Control Greenhouse Humidity
Dehumidifiers reduce humidity by physically extracting water from the air. By using dehumidifiers, you can reduce and control humidity, without opening windows, or ventilating. That means you can keep the greenhouse completely closed, with no air exchange.
This allows you to heat the greenhouse until you reach a comfortable temperature and maintain it without reheating. In fact, by using thermal screens as well, you can further insulate your greenhouse, and reduce your heating requirements even more. Using this method to control humidity, you can save as much as 50% on energy.
A closed greenhouse is a win-win. It also makes humidity control much more effective, as fluctuations become far less common, creating a more uniform climate. This helps eliminate humidity related diseases, increase yields, and promotes uniform, high quality produce.
Monitoring Humidity for Added Greenhouse Energy Control
Using dehumidifiers in a closed greenhouse is just the first step in creating an energy efficient greenhouse operation protocol.
The next step is to introduce monitoring. Using sensors, you can track the relative humidity levels (or VPD) in different areas of the greenhouse. So, you can turn on your dehumidifiers only when it’s objectively necessary, without relying on estimations.
Another factor you should keep an eye on is your dehumidifier’s water extraction rate. Simply knowing the amount of water being removed from the air can help you make better decisions regarding humidity control, as well as irrigation. Your entire water cycle will become much clearer, allowing for better decision making.
Managing humidity is a balancing act. To provide plants with the optimal conditions, your water cycle should be balanced. Plants transpire more than 90% of the water they take in. So the amount of water you extract, both through dehumidification and drainage, should be just a bit less than your irrigation.
Keeping greenhouse conditions balanced is a critical part of plant empowerment, which gives growers the tools to maximize growth and improve crop quality.
For more information on humidity control and greenhouse energy efficiency, contact us.