Why is glass still the reference covering?

Two properties that compound over a project's life. It transmits more light than any alternative, and it does not cloud or yellow, so its optical performance holds across decades rather than decaying. In a sector where a percent of light is a percent of yield, an optical property that keeps its value is a commercial one.

Does choosing glass change the structure?

Yes, and it is routinely underestimated. Glass breaks when the frame moves, which places the house in the stricter of the two European cladding classes and tightens the deflection limits the steel is designed to. A glass house and a film house of identical span in the same wind and snow are not the same structure.

Glass Greenhouse — DutchGreenhouses

Q: Should the whole facility be glass?

No — material follows purpose. Glass goes where light governs, which is the growing area. Polycarbonate and insulated sandwich panels go where robustness or insulation governs: service buildings, side walls, and climates with severe hail or extreme heating demand. A well-specified facility uses both.

Q: How is the covering chosen for a specific site?

From the site rather than from a preference. Solar radiation, heating cost and exposure to hail and storm together point to the optimum for that location and crop. A high-radiation site and a cold cloudy one reach different answers from the same starting question.

The covering that transmits the most and holds it for decades

Glass remains the reference covering for the growing area for two reasons that compound over a project’s life. It offers the highest light transmission of any covering, and it does not cloud, yellow or degrade — so the transmission it is specified at is the transmission it still delivers many years later. Plastic coverings begin lower and fall further, and are replaced on a shorter cycle. In a sector where a percent of light is a percent of yield, an optical property that holds its value is a commercial one.

The choice also changes how the building must be engineered, and that consequence is routinely underestimated. European practice classifies a greenhouse by whether its cladding tolerates movement in the frame. Glass does not — it breaks — which puts a glass house in the stricter of the two classes and tightens the deflection limits the steel is designed to. A glass greenhouse and a film greenhouse of identical span, standing in the same wind and snow, are not the same structure: the glass one is stiffer, and that shows up directly in section sizes and in cost.

Which is why glass is not automatically the answer everywhere on a project. It goes where light governs, which is the growing area. Polycarbonate and insulated sandwich panels go where robustness or insulation governs — service buildings, side walls, and climates with severe hail or extreme heating demand, where a double-walled panel’s insulation outweighs its lower transmission. A well-specified facility uses both, chosen by what each space is actually for rather than by a single house preference applied everywhere.

The specification follows the site rather than a standard answer: solar radiation, heating cost and exposure to hail and storm together point to the optimum for that location and crop. DutchGreenhouses® selects and combines the covering materials with the structure and the climate systems so the light budget, the insulation and the structural class are settled together, around the crop and the local climate. Get in touch to specify the covering for your greenhouse.

From the knowledge base