Model-based decision support system for greenhouse heating temperature set point optimization

Temperature set points for greenhouse heating affect not only greenhouse crop growth development, but also energy consumption for greenhouse climate control. A greenhouse crop growth model and an energy consumption estimation model for greenhouse heating, both were validated under subtropical climate conditions, were integrated to develop a model-based decision support system for temperature set point optimization for greenhouse heating. The system consists of a database(including information about greenhouse, crop and climate data) and three models(a crop growth simulation model, an energy consumption estimation model and a set points optimization model). The input of the system includes greenhouse information, crop information, and outside climate data. The output of the system includes biomass production and energy consumption for heating at different temperature set points for greenhouse heating. The temperature set points for greenhouse heating can then be optimized according to the highest ratio of biomass production to energy consumed or highest biomass production. The scenario study results show that, in the greenhouse cucumber production from the flowering to early harvesting stage in Shanghai, the highest biomass production can be achieved when daytime and nighttime temperatures for greenhouse heating are set at 23℃ and 17℃, respectively; while the highest biomass production EUE for cucumber production can be achieved when the two set points are set at 20℃ and 15℃, respectively. From a practical point of view this system developed in this study may permit improvement in greenhouse climate control in subtropical climate conditions.