Dutch greenhouses move toward energy independence

Using GE’s new Lexan ZigZag sheet polycarbonate roofing material, Hydro Huisman is constructing the first greenhouse that will produce more energy than it uses. Lexan ZigZag sheet double-wall roofing panels provide higher light transmission than single glass, and insulation similar to multiwall glass or PC sheet. These energy-efficient properties will enable approximately two-thirds of the heat generated in the greenhouse to be sold as surplus.

In the Netherlands, greenhouses are currently among the largest consumers of fossil fuel. Concerned about environmental implications and costs, the Dutch greenhouse industry is looking for a way to free itself from energy dependence. With an experimental widespan greenhouse constructed using GE’s new Lexan ZigZag sheet double-wall PC roofing panels, Dutch horticulturalist firm Hydro Huisman aims to turn energy consumption into energy production. Lexan ZigZag sheet roofing raises light transmission levels above those of single glass, especially during non-peak hours/seasons, while ensuring outstanding insulation to retain heat. The Lexan material also provides lighter weight than glass, excellent flame retardance and easy installation.

With its double-wall, zigzag configuration designed specifically for greenhouses, Lexan ZigZag sheet roofing offers a number of key properties. First, its angled design enables the capture of light reflected from the sides of the roof surface, thus increasing the total amount of light transmitted into the greenhouse to 90.9 percent – one to two percent higher than with single glass. Further, when the sun is low on the horizon – during winter months and at dawn and dusk – the material’s channels catch more light than flat glass. Second, Lexan ZigZag sheet offers insulation properties that are similar to those of double-wall glass; the material retains 45 percent more heat than single glass for substantial savings on energy demand: these savings can range from 20 percent to 40 percent.

Further, the Lexan sheet roofing material provides resistance to UV light on the exterior side, an Easy Clean coating, and anti-condensation properties. It is more than 50 percent lighter than glass and virtually unbreakable, making it resistant to hail and easy and safe to work with.

The experimental greenhouse, located in Huissen, will be completed in the latter part of 2005.