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What effect does condensation have on an energy screen?
Growers can limit heat losses in the greenhouse using so-called energy screens. That way they can save energy. However, the screens can get condense due to the difference between the cold top air and the warmer greenhouse air. The Greenhouse Horticulture and Flower Bulbs Business Unit of Wageningen University & Research is researching the effect this condensation has on energy saving.
An energy screen is located horizontally in a greenhouse, at a height of a few meters. If it gets colder outside, a grower can close the screen to decrease energy use. The air under the screen then remains relatively warm and moist, and the air above (under the ridge of the greenhouse) relatively cool and dry. This can cause the effect that the temperature of the screen falls below the dew point. Result: condensation.
This water layer influences the potential energy savings in a number of ways. For example, the material of the screen is less porous, so that less air can pass through. The water itself also retains heat, thus influences the thermal properties of the screen. But what these effects are exactly was not yet well known: there were no good research methods to calculate the effects.
WUR developed a number of methods to measure the effects of condensation on the temperature in the greenhouse. Energy screens from various suppliers are measured with this. The results are used in existing greenhouse climate simulation models. This makes the models more accurate. In addition, suppliers and growers have a better understanding of how the energy screens influence the greenhouse climate and therefore the energy requirement.
The research is funded by the Kas Als Energiebron program.