Generic article


Freesia is a cold, well-lit cultivation in which the crop differs slightly in terms of greenhouse design to other crops as soil cooling is needed to initiate flowering. The cultivation temperature is relatively low forwith 8°C in winter time. The energy consumption for heat is 13m3 natural gas equivalent m3/year. Only 51% of this is needed to keep the greenhouse at the right temperature, but it is estimated that this can be reduced considerably with good insulation. 46% of the heat input is needed to dehumidify evaporated moisture from the crop (50%) and from the soil (50%) at low cultivation temperatures.

In 2011, an energy-efficient cultivation concept was designed. One interesting result from the cultivation concept is the great energy-saving potential of covering or insulating the soil. Another interesting result is that with Freesia, switching from chiller to heat pump turns out to be energetically and economically attractive. The cultivation concept can serve as input for a recalculation of the required capacity when the SON-T lighting is replaced by LED.

Additional lighting with LED has only been examined as a steering light with extremely low intensities in practice. The results were positive, but there are no large-scale experiences with LED, which means that the research can also count on a great deal of interest.