Community Research and Development Information Service - CORDIS

Developement and investigation of evacuated windows based on monolithic silica xerogel spacers

This project aimed at improving the thermal performance of windows through the development of an innovative technology using advanced materials. The work has been successful in achieving most of the scientific and technical goals, with good market potential identified.

Normally the weakest part of the thermal envelope of a building is the window area. This project sought to investigate and develop insulating glazing based on evacuated low density monolithic silica xerogel spacers. While aerogel requires a supercritical drying process, xerogel is dried at atmospheric pressure. It leads, though, to a higher thermal conductivity, with typical values of 0.03 W/(mK). If evacuated below 50-100 hPa, the thermal conductivity will be approximately 33% of the value for commonly used insulation materials. This material is a highly porous material (90%) with a normal solar transmittance of 50% (20 mm thickness). However, if the silica xerogel is not made hydrophobic it has to be protected against water that will demolish the pore structure of the material due to surface tension. For its application in window glazing, the protection against water is achieved by placing the xerogel between two sheets of glass and sealing the rim.

Reported by

Anker Engelundsvej 1, Building 101
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