Vacuum insulation is an appropriate alternative for more energy-efficient buildings. This method is based on exterior insulation which has plenty of advantages over inside insulation: cold bridges and interstitial condensation are avoided and internal walls are retained as heat-sinks.
VIP (Vacuum Insulation Panel) is an efficient example compared with other available options (EPS-Expanded Polystyren, XPS-Extruded Polysyren, stonewool, fiberglass, Phnolic foam, PUR-Polyurethane,...). The isolation consists of light metal formable heat-sealed panels which are filled with nanoporous material. This inner filler comprises of fumed silica or a combination of superfined fibreglass and phenomic foam.
VIP has a very high insulation capacity. The vacuum inside highly lessens the overall conductivity; a 2-3 cm VIP panel is equivalent to 10-15 cm of mineral wool insulation and thus saves much space. Previously, the technique was only used in fridges and refrigerators.
There are nevertheless also some disadvantages with VIP: costs are still relatively high. More ubiquity in the future will certainly decrease prices and make the choice of material more economic in both short- and long-term. Another problem is that utmost care is required during transportation and construction. The quality decreases over time in a way that the lifetime is 30 - 50 years. Panels should thus be easy to access and replaceable.
Sources:
http://www.byggahus.se/artiklar/nya-effektiva-material-for-miljon
http://www.starch.dk/private/energy/insulation.asp