Plastic glazing yield surplus green energy

By adopting double walled polycarbonate roofing panels, Dutch greenhouses are being constructed that will produce a net energy surplus instead of requiring heating. The Dutch greenhouse industry recently invited builders to create solutions that would free growers from dependence on fossil fuel. The challenge was taken up by Hydro Huisman, a large hydroculture company, which has built a 6,000 m2 area experimental greenhouse, with 12.6m spacings between vertical supports. The roofing will be 'Lexan' polycarbonate double walled 'Zigzag' sheeting made by GE - Plastics. The makers claim that the material provides greater light transmission than conventional single sheet glass, and insulation similar to that of multi-wall glass or PC sheet. It is also said to provide resistance to UV light on the exterior side and anti-condensation properties as well as retaining 50 per cent more heat than single glass. It is lighter in weight than glass, hence the wide spans, and is hard to break as well as being flame retardant and recyclable. The angled design enables the capture of light from the sides of the roofs, increasing the amount of light transmitted into the greenhouse to 90.0 per cent, one to two per cent higher than with single glass. The greenhouse will be equipped with a special heat exchanger that can either heat or cool water from climate control. The excess energy will be used to heat conventional areas of the 26,000 m2 area structure and can also be sold to nearby greenhouses. Stef Huisman, general manager of Hydro Huisman said, "Our industry has a vision of independence from fossil fuels and we believe Lean Zigzag sheet roofing can make that vision a reality." GE Plastics Hydro Huisman