Keywords:building thermal performance, aerogel-based render, thermal bridge, building retrofit
In France, and in Europe in general, the building sector is the largest consumer of energy and accounts for about 43% of the total energy consumption and around 25% of CO2 emissions . The building sector offers significant potential for improved energy efficiency through the use of high-performance insulation and energy-efficient systems
In this study, the thermal behavior of buildings with an advanced thermal insulation system, particularly, with the aerogel-based rendering/mortar exterior insulation system is examined. In addition to new buildings, the rendering is very suitable for application to retrofit existing ones since it has a high insulation performance and its application is easy, compatible with the traditional masonry facades, and using the ordinary well-known techniques. Numerical modeling simulations are carried out on three different scales: (a) 1D envelope scale to examine the aerogel-rendering’s impact on the thermal and moisture transfer of exterior walls, (b) 2D envelope scale to examine its impact to limit the heat losses through some types of thermal bridges, and (c) full scale house to examine its impact on reducing the heating demands.
Results show that adding the aerogel-based rendering on the exterior surface of the un-insulated or the already internally insulated walls reduces significantly or removes the moisture risks. It reduces significantly the wall heat losses, especially for old un-insulated buildings, and consequently the building’s energy consumption. In addition, this insulating rendering can act as a very suitable solution for some thermal bridges such as the window reveals. Due to its application technique and its high insulating performance, a small thickness can have great impact on reducing these heat losses. So, this type of insulating renderings/plasters can serve as a good solutions for places where traditional insulation is difficult to apply or where small insulation thicknesses are needed due to space or construction constraints.