In the Benelux and also in other Western European countries, many horticultural and ornamental crops are grown under glass. Growing vegetables under glass has the advantage that cultivation is not dependent on weather conditions and can take place all year round. The area of greenhouse horticulture in the Benelux is about 12,000 ha, of which about 2,000 in Belgium and 10,000 in the Netherlands. The area of greenhouses has been fairly stable in recent years which means that mainly replacement of existing greenhouses is taking place. Of all the glass greenhouses in Europe, 80% come from the Netherlands. There are two types of greenhouses that are the most common; the Venlotype and the Wide-Top.
The Venlokas is the most frequently built cabinet type worldwide. It is made of glass, with a skeleton of galvanized steel and aluminum for the glass parts. The Venlo greenhouse is originally typified by a hood width of 3.20 meters. Various other widths are now also available.
Usually two, three or four hoods are supported on one horizontal span (lattice), so that in the greenhouse the free space between the supporting legs is much larger: 8 to 12.80 meters. The distance between the columns in the direction parallel to the gutter has also continued to increase over the years.
Previously, this section size was 3 meters. Since the introduction of glass with a width of 1 meter and more, the section size has become 4.5 or 5 meters. The height of the legs is between 6 and 7 meters. This is also called the gutter height.
The wide-roofed house has essentially the same construction as the Venlo greenhouse. The span of the trusses is standardized to sizes with a roof width of 12.80 meters. Other sizes are also possible. The leg height is usually 6 meters.
The legs and frame of both cabinet types are steel sections. Each rests on a concrete foundation, which sometimes must also be underpinned. Horizontal trusses and diagonal support beams are also steel. The greenhouse deck containing the glass is usually made of aluminum.
The amount of steel per square meter of built-up area varies from 3 kg/m2 to 12.5 kg/m2 This depends on the height of the greenhouse and on the span of the girders.
Above all, the type of greenhouse to be grown largely determines the choice of type. Although the technical lifetime of the greenhouse exceeds 40 years, the economic lifetime of a greenhouse will often be between 15 and 20 years.
Duplex is the combination of a paint system (organic coating) on hot-dip galvanized steel. A paint system can consist of one or more layers of powder coating or wet coating. By applying an additional coating, better light reflection can be obtained. This also prevents zinc corrosion
NEN 3859
Horticultural greenhouses: design and construction – horticultural greenhouses for the commercial production of plants and crops
NEN-EN 1990
Eurocode: foundations of structural design
BRL 8000
Assessment guideline for design and construction of horticultural greenhouse, structures and installations
NEN EN ISO 1461
Coatings applied by hot-dip galvanizing to iron and steel objects – specifications and test methods.
