Greenhouses are great at retaining heat and raising temperatures to provide ideal crop-growing conditions when it's cold outside. However, during the summer months, many growers face the opposite issue. The temperatures outside rise higher than what is ideal for the plants, and heating and retaining heat are no longer beneficial but may be destructive.

During summer days, greenhouses absorb a lot of heat. They then need to cool down during the night to provide a balanced daily temperature average. Failing to do so may slow down growth, lead to smaller yields, and lower quality output.

Cooling the greenhouse when it's hot
So, in order to continue to optimize your cultivation, you may need cooling during the summer. "But investing in HVAC, or other air conditioning systems, often requires a large investment," the team with DryGair says. "These systems can require extensive infrastructure, making them expensive both to install and to maintain. Understandably, many growers prefer not to invest in complex cooling systems that are only necessary for a short period."

The problem with humidity
"The problem with high temperatures becomes even greater when humidity is high outside, as is common during the summer. In this case, ventilating to release moisture may lead to even higher temperatures in the greenhouse, which can harm the plants", they add. "So, the only effective way to control humidity in this case is to use active dehumidifiers. These extract water vapor from the air to efficiently reduce humidity in the space. By using dehumidification to control humidity, you can keep the greenhouse closed and avoid introducing more heat."

How cooling connects to humidity control
"The need to both cool and reduce humidity actually holds the key to effective cooling at a relatively low cost," they add. The company, a dehumidifier manufacturer, offers an innovative solution to this issue. All DG dehumidifiers are equipped with a patented air circulation mechanism that utilizes powerful fans to expel the treated air in all directions to reach the entire space.

The company offers a variation on their most popular units, the DG-12 and DG-6, which allows it to cool the outgoing air. Using this system, growers can distribute cool air throughout the greenhouse without requiring ducting or complex HVAC systems. The units only require a cold water source, for example, from a chiller.

According to the technical details, DryGair combined with cooling can provide as much as ~32kW of cooling (110,000 BTU/h). In this example, cold water is fed into the unit at 7°C (44°F) at a rate of 80 liters per minute (21 gallons). This was tested under greenhouse conditions of 24°C (75°F) and 80% relative humidity.

By combining dehumidification with cooling, you can lower greenhouse temperatures when necessary, using the same system that controls humidity.

The same system can also be utilized during the winter to provide additional heat. By simply introducing hot water to the system instead of cold water, you can easily switch from cooling to heating.

DryGair's team offers free consultations, and is available through the company website.

For more information:
8 Hamanofim St, Herzliya
Tel.: +972-9-7730989