IMPROVING RESISTANCE OF GREENHOUSES TO WEATHER HAZARD THROUGH STANDARDS ENFORCED BY INSURANCE COMPANIES

About 2000 ha of greenhouses are operated in Israel.
More than 20 different designs are offered by some 10 manufacturers.
In addition, some of the simple types are manufactured by unexperienced local contractors and operators.
Most of the greenhouses (nearly 90%) are covered by polyethylene sheets which are replaced every season.
The use of reinforced P.V.C. sheets, rigid P.V.C., polycarbonate and glass is rare due to economic reasons, especially for non-heated greenhouses.
Only about 10% of the greenhouses (200 ha) are heated, mainly with hot air from oil fired heaters.
Expansion of greenhouse area is considerable and reaches about 5% (i.e. 100 ha) per year.
The policy of the government is to support, by subsidies and loans, expansion of greenhouse horticulture.

Insurance of farmers against weather hazard is also supported by the government.
This support is implemented by a government insurance fund which operates in a similar manner to an insurance company.
Greenhouse structures are usually made of light galvanized steel.
Reputable manufacturers use certified designs that meet Israeli standards.
These standards specify a design wind velocity for a certain duration, on which the strength calculations are based, assuming a rigid envelope.
Lighter and cheaper structures are calculated for a reduced wind velocity and duration.
They are used for greenhouses in areas in which the incidence of strong winds is not so high.

II Workshop on Greenhouse Construction and Design

I. Segal, G. Felsenstein

https://doi.org/10.17660/ActaHortic.1990.281.12