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Screen fans secures better climate and lower humidity
There are several methods to prevent high humidity in the greenhouse (which may cause diseases in the crop). More and more growers opt for a screen fan, which blows dry air into the greenhouse. This method is effective, according to research by Business Unit Greenhouse Horticulture and Flower Bulbs of Wageningen University & Research.
High relative humidity can be stopped by heating at a higher temperature: warm air can contain more water. However, this is not an energy-efficient solution. Another method is to make a gap in the closed screen. But this causes an uneven distribution of hot and cold air in the greenhouse.
That is why more and more growers switch to a screen fan. This small fan is mounted above the screen, where the air is cooler, and therefore contains less moisture than the air under the screen. By blowing that dry air into the greenhouse, the moist air is expelled.
At a rose nursery, WUR investigated the effect of screen fans on the temperature distribution in the greenhouse. Within the width of a trellis, the fans all blow in one direction: it was expected that the temperature at the end point (the facade) would be very low. This was not the case. Temperature differences averaged 1 ° C and these differences were caused by the wind direction outside, not by the blowing direction of the fans.
Last year, WUR investigated the effects of the use of screen fans in winter at a number of chrysanthemum nurseries. The first results show that both energy consumption and relative humidity decrease. In the coming year, WUR will investigate whether screen fans are also effective in the summer for lowering the temperature and humidity in the greenhouse.
This research is funded by the Ministry of Agriculture, Nature and Food Quality and the 'Kas Als Energiebron' program. from Glastuinbouw Nederland.