Energy-optimised buildings usually require a thick thermal insulation. With passive houses insulation thicknesses of 30 cm and more are not uncommon. If the external dimensions of a building are predetermined, e.g. by existing neighbouring houses or building lines, high energy-oriented quality is achieved at the cost of the internal surface area.

Conversely, until now it has been difficult to achieve high-grade thermal protection if only limited space is available or thick insulation layers are unwanted. This can affect the retroactive insulation of an individual terraced house facade, but also “classic” thermal bridges such as shutter boxes, window reveals and balconies.
In such cases insulation with vacuum insulation panels (VIP) can be a solution. The panels can achieve a much greater insulation effect with the same thickness as conventional materials. Thus slim structures are possible, even for well insulated buildings or building sections. VIPs are made up of a porous, pressure-resilient core, sealed in a diffusion tight high-barrier plastic film in a vacuum chamber. The technology used for the manufacture of cooling and refrigerating units has now been developed – also in the framework of research projects – for application in construction. To avoid relativising the good insulating effect in the centre of the panel, the thermal bridges at the edge of the panels and other connection points first had to be minimised.

Furthermore, it was necessary to develop vapour diffusion tight joints for the elements as well as VIP connections for floor, facade and roof. Also necessary were practicable solutions as to how the highly sensitive insulation material should arrive at the place of installation in undamaged condition and how it should provide fault-free service over many years. Following the first field tests with VIP insulation on individual building elements, demonstration buildings should now provide more detailed information for planning and building with VIP. The Federal Ministry of Economics and Technology (BMWi) is therefore sponsoring the planning, optimisation and monitoring of a passive house completely insulated with VIP prefabricated elements. The building was constructed in 2005 and since then continuous measurements have been taken. The following presents the experiences with the VIP elements, mainly independent of the elaborate building services equipment.