The better a building is insulated, the less heat is lost in winter—and the less energy is needed to achieve a comfortable room temperature. The Swiss Federal Office of Energy (SFOE) regularly raises the requirements for building insulation.
Traditionally, insulating layers are added to finished walls. Increasingly, however, self-insulating bricks are being used—saving both work steps and money, and opening up new architectural possibilities. Insulating bricks offer a workable compromise between mechanical and thermal properties and are also suited for multistory buildings. They are already commercially available in numerous models: Some have multiple air-filled chambers, others have larger cavities filled with insulating materials such as pearlite, mineral wool or polystyrene. Their thermal conductivity values differ depending on the structure and filling material. In order to reach the insulation values of walls with seperate insulating layers, the insulating bricks are usually considerably thicker than normal bricks.
Aerogels are a relatively new insulating material in the building sector. The base for the material are mostly silicates, but in volume it consists of more than 90 percent of air-filled pores with sizes in the nano range. This minimizes the energy transfer through the movement of the air molecules—in other words, aerogels are highly efficient insulating materials. In addition to their thermal properties, aerogels are vapour permeable and absorb almost no moisture. They are additionally recyclable, non-toxic and non-combustible. This makes them an almost ideal thermal insulation material for buildings.
Empa researchers have now replaced perlite in insulating bricks with Aerogel: a highly porous solid with very high thermal insulation properties that can withstand temperatures of up to 300°C. Researchers have previously used it to develop a high-performance insulating plaster, which, among other things, allows historical buildings to be renovated energetically without affecting their appearance.