The design of modern greenhouses is based on a compromise between a maximized transmission of solar radiation and a minimized heat loss within an economic context. This could be satis"ed by the use of transparent double-layered zigzag plates as a covering material. The MatLight computer model was de
Review Paper (SE—Structures and Environment): Radiometric and Thermal Properties of, and Testing Methods for, Greenhouse Covering Materials
✍ Scribed by G. Papadakis; D. Briassoulis; G. Scarascia Mugnozza; G. Vox; P. Feuilloley; J.A. Stoffers
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 467 KB
- Volume
- 77
- Category
- Article
- ISSN
- 0021-8634
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✦ Synopsis
In this paper, the most critical physical properties for the greenhouse covering materials are reviewed. The physical properties considered include the radiometric properties (transmissivity, re#ectivity and absorptivity) over several radiation bands and also the K-value (the overall heat transfer coe$cient). Only a few standard methods for testing these physical properties of covering materials for greenhouses exist. Usually, some of the testing methods used for plastics in general, are also applied to greenhouse covers despite important functional di!erences. These testing methods are reviewed with regard to their suitability for application to greenhouse covering materials. Also, reported values of the most important physical properties of greenhouse covering materials are presented and reviewed. The values presented are found to vary considerably among the materials considered. These variations are attributed mainly to the testing method employed and also to the type of the material. Existing testing methods are used arbitrarily and technical information is presented in a rather confusing way. Modi"cation of existing testing methods is required because, in most cases, they are insu$cient for greenhouse covering materials. Also new testing methods should be elaborated, and specially designed for greenhouse covering materials. 2000 Silsoe Research Institute * Symbols in this column are explained in Appendix A.5 (1) According to ASTM D 570 water adsorbance; (2) According to DIN 53122 (water adsorbance); (3) According to DIN 53473 (water adsorbance); (4) According to DIN 53495 (water adsorbance); (5) ASTM D 3985. R thermal conductivity value, W/mK). S new sheets without condensation. A di!use part of direct transmittance.
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