The solar greenhouse : a highly insulated greenhouse design with an inflated roof system with PVDF or ETFE membranes

In a co-operation project of Wageningen University (Wageningen UR), Agrotechnology & Food Innovations B.V. (A&F), Priva Hortimation B.V. and Hyplast N.V. (Belgium) a greenhouse for the future has been developed. The project has four lines, namely 1. lowering the energy demand, 2. using solar energy for heating (greenhouse as solar collector), 3. modifying climate control and dehumidification and 4. developing of the highly insulated greenhouse. This paper deals with the development of the so-called Solar Greenhouse, the structure and cladding material and the (natural) ventilation openings. The aspects that play an important role in the process of development of the greenhouse are the strength of the structure, the light transmittance, the material consumption and the expected greenhouse climate. The high demands for energy savings lead to a greenhouse covering with a high insulation value and at the same time a high light transmittance. Advanced materials like fluor polymer films in double or more layers with the space in between inflated have these qualities. The most perspective greenhouse geometry is a saw-tooth roof structure with roof inclinations of 200 and 300, a span width of 10m and a vertical opening of 2 m for natural ventilation. The module for the greenhouse is repeatable in both directions to a big area. Caused by the asymmetric geometry of the greenhouse (openings oriented on one side) the influence of the wind and wind direction is extensiv