Walking measuring box takes its first steps
Research into semi-closed greenhouses have shown that during the night the local differences in temperature and humidity can increase by 8 degrees and 30%. With one climate box per department, possible condensation in all spots of the greenhouse cannot be discerned. To prevent diseases, a wider margin has to be set on the climate computer and any additional energy consumption has to be taken for granted.
Within the Healthy Greenhouse project there is research underway to study whether the climate can be controlled based on more measuring points. The aim is to prevent condensation by controlling the area with the lowest moisture deficit and to save energy when possible with tighter control (a smaller margin). Because the climate can vary locally, this doesn’t always have to be the same place. In this way, there is a control system where the measuring box can take action and immediately intervene if the moisture deficit falls below the desired threshold.
A more homogeneous climate
In the spring of 2014, (Germany) researchers of Wageningen University Greenhouse Horticulture in Straelen controlled the climate based on several wireless sensors for temperature and humidity for the first time. The working of the new control unit (with 8 sensors) was compared to that of the single climate box in a tomato greenhouse of 250 m2. In two periods of a month wider RH margins of 3% and 5% were tested. In both situations the walking measuring box gave a more homogeneous climate and less energy was used, sometimes as much as 10%. These results are encouraging. Further research during other seasons and with other crops still has to be implemented to see whether these results are really feasible in all circumstances. The walking measuring box will be presented at the Demonstratiedagen Gezonde Kas 2014 (Demonstration Days Healthy Greenhouse 2014) in October.