The research project which produced a window with improved insulation properties was carried out by the Danish window manufacturers Pro-Tec Vinduer A/S and designed in close co-operation with the Danish architects Friis & Moltke A/S.
The window is part of a large development programme known as “Windows of the future for houses of the past” initiated by the Copenhagen-based urban renewal company SBS on behalf of the Land-owners’ Investment Association. The idea is to kick-start the development of new and better types of windows, since many windows need to be replaced after a relatively short number of years due to either the use of wrong materials or poor workmanship.
”The project gave Pro-Tec the opportunity to enter an entirely new field,” says Bjarne Haulrik, Managing Director of the company, “and we found the material we needed at Fiberline Composites in Kolding, Denmark, which is one of the world’s leading manufacturers of state-of-the-art GRP profiles. Fiberline employs a high-tech production process known as pultrusion and manufactures GRP profiles with high insulation properties for many different industries.”
”Together with the architect, we decided to reinvent the window,” Bjarne Haulrik continues. “Instead of updating familiar profiles and products, we began searching for a new material that would provide all the properties necessary for the window of the future. This was when we became aware of GRPs as a strong and rigid material that would enable production of narrow and complex profiles. GRP profiles have enabled us to design windows with narrower, more elegant frames and still incorporate all the functions of a modern window.”
The engineers involved in the project set themselves the goal of designing a new window devoid of thermal bridges. In Denmark, figures indicate that nearly half of the energy used in heating new buildings disappears through windows and doors that have poorly insulating frames and sills.
”The new windows ensure that home-owners will no longer have to contend with condensation, and heating bills can be reduced. The GRP material prevents thermal bridges and insulates so well that the U-value of the total window structure is reduced to as low as 1.3 W/m2K. This effectively anticipates new Danish and EU building regulations that are expected to tighten U-value requirements which are currently 1.8 W/m2K,” says Bjarne Haulrik.
Moreover, the window cannot rot. It has a very long service life that is well-suited to the fluctuating weather conditions of Northern and Central European countries, and requires practically no maintenance. Paint does not peel because it adheres well to the GRP material, yet homeowners are still able to change colours if they like.
While the window still exists only as a prototype, Pro-Tec expects to have the finished product ready for the market by the end of 2005.
”We believe that the attractive proportions and thermal properties of this window will be the ideal supplement to our product line. The narrow mullions and transoms combined with large openings for light will enable us to develop several variations of the finished window that will complement old buildings as well as new. And since they will weigh 25 per cent less than traditional windows, they will also benefit window installers’ backs. This is yet another argument in favour of GRP materials for windows that will become more prevalent in future,” concludes Bjarne Haulrik.
The new GRP window shown to the right alongside a window from the 1980s. The frames, mullions and transoms of the GRP window are noticeably narrower, allowing more light to enter a room.
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