That plants grow better if grown in a greenhouse in the correct climate is nothing new. Dutch researcher Rachel van Ooteghem, of the Wageningen University and Research Centre, has designed a control system for an improved solar greenhouse that yields more. In the new greenhouse, good climate control with sustainable energy resulted not only in an increased crop yield but also a lower gas bill.

Factors such as temperature, carbon dioxide (CO2) concentration and relative humidity must be controlled as accurately as possible for optimum crop growth. Van Ooteghem designed an optimal control system for a solar greenhouse with an improved roof cover, heat regulation system and humidity regulation system. In current greenhouses the climate is often adjusted with the help of fossil fuels: the heating in the greenhouse is switched on. Furthermore the greenhouse can be ventilated to decrease humidity and reduce the temperature. Thanks to modifications and Van Ooteghem's new control system less energy is lost and excess heat is reused. This means that sustainable energy can be used to control the climate in the greenhouse efficiently.

Control system

Van Ooteghem has developed a control system that maintains the correct climate in the greenhouse, whatever the weather outside. Different climate factors in the greenhouse, such as temperature and relative humidity, can be measured. Subsequently the correct adjustments to the settings of the greenhouse are made to maintain the optimum climate. The precise nature of an 'optimum' climate depends on the objective. For example, the aim might be to maximise the crop yield while minimising the gas usage. With the aid of a model of the greenhouse climate and the crop the new control system can increase the crop yield by 39% while reducing the gas usage by 52%.

Rachel van Ooteghem's research was funded by The Netherlands Organisation for Scientific Research (NWO).