The Solar Greenhouse; technology for low energy consumption.

摘要

High energy consumption is still an obstacle for sustainable greenhouse production. Therefore reduction of absolute energy consumption has high priority. In the Solar Greenhouse project, the ultimate goal is to develop a greenhouse system with a fully sustainable energy supply. The first step in the project is to decrease greenhouse energy demand substantially. Therefore, new covering materials have to be developed enabling the combination of high insulation with high light transmittance. New flexible or rigid plastic materials with geometry designed for high light transmittance are promising. Also coating of glass is promising. In connection to improved insulation, the greenhouse itself and its climate conditioning has to be redesigned. Active, energy friendly dehumidification has to be developed. Progress on this field is reported. On a year round base, sustainable solar energy is sufficient to cover the low heat demand of well-insulated greenhouses, even in North Western Europe. Long term energy storage in aquifers can link available surplus of sustainable energy in summer with energy demand in winter. Then energy is available at low temperature levels, so a heat pump has to be applied. From crop science, insight is given in potentials of a crop to integrate temperature. In this way the overall heat demand of a greenhouse can be decreased too. Crop tolerance has to be quantified to exploit it in control strategies. In these strategies, costs and benefits can be optimized applying optimal control theory. The implementation of models is essential in greenhouse climate control enabling the prediction of systems behaviour. The accuracy of the models can be improved by updating and tuning them through actual greenhouse climate and crop measurements. Therefore crop (soft) sensors have to be developed enabling phytomonitoring.