Efficiency verification of a combination of high performance and conventional insulation layers in retrofitting a 130-year old building

Abstract The performance and applicability of a newly developed high efficiency insulation material to retrofit old buildings was investigated in a pilot project supported by the Swiss Federal Office of Energy (SFOE). One half of an old stone walled building situated in the city of Zurich dating from 1877 has been retrofitted by means of a high efficiency thermal insulation layer of 20 mm thickness containing aerogel on the external side, and a conventional insulation material of 20 mm on the inner side of the stone walls. This procedure promised a theoretical reduction of the steady state U -value of the wall by approximately a factor of 3 without compromising the original appearance of the building. To verify this, in-situ measurement of the U -value as well as infrared thermography has been performed during the cold weather period of early 2011 when there was a large temperature gradient between indoor and outdoor climate.