DESIGN, CONSTRUCTION AND MAINTENANCE OF GREENHOUSE STRUCTURES

In this paper a review is given about the effects of different parts of the solar radiation and its importance for plant growth in greenhouses. Besides the most important visible part of the light (PAR), ultraviolet (UV), near infrared (NIR) and far infrared (FIR) are discussed. The strength of the greenhouse structure can be calculated following the new European Standard for Greenhouses EN 13031-1. The orientation and the roof inclination at the greenhouse have limited influence on the light transmittance. The most important material properties of greenhouse cladding materials are presented for glass, plastic sheets (PMMA and PC) and plastic films (PE, PVC and ETFE). These properties can be modified in the different materials, which leads to improvements of the materials with respect to light transmission, heat transfer, condensation behaviour, etc. Some recent results of research of greenhouse cladding materials and structures are described, like `floating greenhouses?, `closed greenhouses?, ETFE membrane, a greenhouse for tropical lowland, zigzag-shape double PC-sheet and microstructural coated glass.