The principles of thermal insulation were known even by the Pueblo Indians, who built their houses with air dried bricks (known as adobe bricks) made of clay and sand. In dry areas, adobe bricks heat up in the sun and radiate the heat into the environment during the night. Due to this effect, the buildings remained cool during daytime and were warm at night. In the 16th century, the art of making adobe bricks spread from Peru and Mexico to Spain, where, as in northern Africa and the Middle East, they are still used today for building houses. This ancient Indian technology had many merits, but adobe bricks cannot meet the demands of modern building construction. Lack of resistance to moisture is just one of the reasons why the bricks would soon cause problems in our latitudes. Then there is the issue of thermal insulation; against the background of ever rising energy prices, this has now taken on a new dimension. Energy-saving potential is in thermal insulation, completely irrespective of whether a building needs to be heated or cooled.
Heat loss via radiation is usually underestimated. And this, although is precisely the surface temperature in our immediate surroundings, such as walls, floors or ceilings, that have a crucial influence on our personal comfort. The U value describes the heat flow in watts (W) that passes through all the layers surrounding a building element, over a surface area of 1 m² due to a temperature difference of 1 K (W/m²K). The smaller the U value is, the less heat is lost by the building element. "The U value is a means of providing realistic information on the heat losses by various building elements or combinations thereof," explains Klaus Bonin, technical expert at WACKER's Construction Polymers business unit.