Vacuum insulation has grown from a research subject to a versatile construction material in the past ten years. This is also proven by the increasing number of national technical approvals for this type of insulating panel. At a conference by the German Institute for Research on Building, Urban Affairs and Spatial Development (BBSR), researchers and manufacturers provide information on the development of the technology, its application in building practice and the future perspectives of this high-efficiency insulating material.

For vacuum-insulated panels (VIP), sheets made of compressed silica powder, which is an extremely microporous material, are enclosed in a gas- and water vapour-proof enclosure made of special high-barrier films and evacuated. Their insulating effect exceeds conventional insulating systems five to tenfold. This means that a very thin structure already provides excellent performance – a major advantage in tight spaces, for high site prices or when designing slim façades. However, the technology poses considerable challenges in terms of the materials and processing.

While the silica core of itself offers better thermal protection than conventional insulating materials, the preservation of the vacuum in the core is the key to maximising its performance. The enclosing material is also crucial. Dr. Noller from the Fraunhofer Institute for Process Technology and Packaging reported on the goals and processes currently used in developing far better sealed foils. Quality assurance in production, and in particular during transportation and installation, is another critical aspect. Each manufacturer approaches this differently. However, the same strict requirements apply to all panels with a national technical approval. For example, they may only be installed by qualified personnel.

However, even if everything goes smoothly until installation, the question as to how long the vacuum quality lasts, and thus the insulating effect in the panels, remains. VIP elements age: gases which penetrate through the barrier film and sealed seams increase the thermal conductivity slowly but surely. Laboratory testing simulations and rapid test processes by ZAE Bayern and FIW München lead us to expect that the thermal conductivity of VIPs in the construction sector only increases to a minor extent, even over multiple decades. Dr. Heinemann from ZAE Bayern emphasised that repeated analyses of buildings insulated with VIP over an extended period did not reveal any unusual symptoms of failure – even in applications where the vacuum insulation was over 10 years old. The VIP-PROVE research project, funded by the German Federal Ministry of Economics and Technology, verified this.

In future, a sensor transponder (RFID) which monitors the pressure and temperature in the panels, developed by institutions belonging to the Fraunhofer Association, will facilitate evaluation over the entire service life.