ABSTRACT

The advantages of using optimal instead of conventional greenhouse climate control can be summarized as follows. An optimal control approach to greenhouse climate control fully exploits scientic quantitative knowledge concerning the greenhouse, the greenhouse equipment, and the crop. These are all captured in a mathematical dynamic model. Furthermore the goals of a grower, which usually come down to maximizing prot, are also stated quantitatively and explicitly in terms of a mathematical cost function that is maximized. This cost function is based on auction prices obtained for the crop as well as the costs associated with greenhouse climate management, such as heating costs. The latter costs are often underestimated by growers that focus on the welfare of the crop. Optimal control reveals that crop welfare may be retained against less operating costs such as heating. Sometimes a slight loss of crop quality may save a lot of operating costs leading also to higher prots. These outcomes are partly due to the fact that the optimal controller cleverly exploits weather predictions and measurements. The tuning of an optimal greenhouse control system is performed by changing something in the order of ten settings that all have a clear meaning and interpretation. Conventional greenhouse climate controllers usually have several hundreds of settings the meaning of which is usually not very transparent. Growers often use only a few of these settings. In general, however, no two growers use the same settings to control their greenhouses.