Tomatenteelt in de hooggeïsoleerde VenLow Energy Kas

In the research program Greenhouse as Energy Source aims at having energy-neutral operated greenhouses by 2020. Therefore, a reduction of the energy use is important. The highly insulated VenLow Energy greenhouse have shown a low energy consumption for several years and in 2014 it was attempted to bring it below 10 m³ of natural gas equivalents per m² without a lowered production. To achieve this the leakage had to be reduced further and the screen quality was improved and a high humidity control setpoint was accepted. This in order to reduce the evaporation. Also the manipulation of the EC in the slab could lower the crop transpiration related energy consumption. The experiment showed an energy consumption of 8 m³/m² per year without a decreased crop production. This is far below target, but 2014 was a historically warm year. However, simulations showed that even in an average Dutch year the measurements taken would have met the target. The manipulation of the EC of the slab worked adversely, meaning that it increased the crop transpiration. The conclusion reads that the measures taken in the greenhouse make a productive tomato crop with less than 10 m³ of gas equivalents per m² per year realistic. With respect to the climate, a high humidity must be accepted and a shortened growing season running from mid-January to late November. A tomato variety like Komeett will yield at least 70 kg/m² can be expected, providing that CO2 dosing is not related to gas consumption for heating.