RESEARCH ON INSULATING GREENHOUSE CLADDING MATERIALS

In the development of these panels the relevant manufacturer and greenhouse builder have placed particular emphasis on attaining a high insulation value and an acceptable light transmittance. Not enough specific research has been carried out on the strength, impact strength, ageing, etc. However, practical experience has shown more than clearly that it is wrong to turn a blind eye to one or two properties and to pay insufficient attention to the remaining properties.

With this type of PVC sheeting with an acrylic coating the impact strength is clearly one of the properties that is definitely inadequate. Of the 20 ha (49 acres) 5.6 ha (about 14 acres) have been destroyed during hail storms by falling hail stones. Many holes are produced especially in the outer skin of these panels (to give some idea 5 – 10 holes per m²).

This great damage gave a direct impetus for the setting up of the Committee for the Research on Insulating Greenhouse Cladding Materials and Constructions. The objectives of this committee are:

1. the determination of the relevant material properties of insulating greenhouse cladding materials by means of research;
2. the development of standard testing procedures for these materials;
3. the preparation of guidelines for the construction of insulated greenhouses with an adequate durability and safety, as well as with a well predictable insulation value and light transmittance, so that the grower can make a considered choice.

The main objectives in this are the development of standard testing procedures and the preparation of guidelines. New materials being introduced and materials not included in the research program can be tested, once the test procedure has been laid down, with respect to the criteria before they are used in practice. The committee is made up of representatives from the following bodies: the Ministry of Agriculture and Fisheries, growers organizations, the banking world, insurance societies, research and advisory services.

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