Optimal control of a solar greenhouse

A solar greenhouse has been designed that maximizes solar energy use and minimizes fossil energy consumption. It is based on a conventional greenhouse extended with a heat pump, a heat exchanger, an aquifer and ventilation with heat recovery. The aim is to minimize fossil energy consumption, while maximizing crop dry weight and keeping temperature and humidity within certain limits. These requirements are defined in a goal function, which is minimized by optimal control. A greenhouse with crop model is used to simulate the process behaviour. It is found that open loop optimal control trajectories can be determined. The boiler use is reduced to a minimum, thus reducing fossil energy use. Compared to a conventional greenhouse it is found that the energy costs are decreased and the crop dry weight is increased.