One of Schenkeveld Tomatoes' new greenhouses is equipped with a ventilation system. This allows greenhouse air to be mixed with outside air, reheated to greenhouse temperature, and then blown above the crop via hoses. The purpose of such a system is to accurately dehumidify the greenhouse air. In any case, more accurately than with screen vents or window vents. At Kas als Energiebron, Marcel Raaphorst of Wageningen University & Research's Glasshouse and Flower Bulbs business unit shares an update.
Every m3 of outside air you exchange too much costs energy, and every gram of moisture you drain too little puts you at risk of disease or physiogenic abnormalities, he writes. "Moreover, with trunks, it is easier to blow in the same amount of air everywhere, so horizontal temperature distribution is better than if it is left to chance with gaps."
Wageningen University & Research monitored this system in its first year of use. Smoke tests and the deployment of a sensor network showed that temperature distribution is indeed good. However, some areas for improvement did emerge. For instance, the distribution could be even better if more air were blown out to the sides of the air handling units. The loss of light from the hoses is a disadvantage, but that disadvantage is small because there is only one hose per 40 meters, and it is transparent too.
Schenkeveld's cultivation manager also sees the benefits of the system on the greenhouse climate. Read the whole item at Kas als Energiebron here.