Thermal optimization of curtain wall façade by application of aerogel technology

Abstract

The paper illustrates the use of aerogel technology in façades to reduce thermal bridging and limit condensation. Additionally by mitigating local thermal bridges the indoor climate, especially draught and molds creation, can be eliminated as the surface temperature increases and prevents these negative factors. Curtain walls, in comparison to opaque wall, are often not designed in an energy efficient way and can be large contributors to heat loss of buildings. This is common for curtain walls in Asia and North America, where the energy requirements are not as demanding as in Europe. Building envelopes have many details which can easily introduce thermal bridge due to limited space of insulation or incorrectly solved construction detail. The heat flow through a poor thermally-performing detail, e.g. exposed concrete slab, could account for over 40% of the heat loss of the façade. The contribution of a well-insulated slab could be less than 10%. Unfortunately, traditional insulation techniques are often not suitable due to limited installation space. This paper discusses several case studies whereby the performance of a reference case is compared to a case with a thermally optimized façade implementing Building Insulation Blanket (BIB), which uses silica based aerogel technology. The thermal conductivity of BIB can be as low as 0.015W/mK, and together with its high flexibility and fire resistance enables new design possibilities. The use of BIB in the case studies, contributed to the reduction of overall curtain wall thermal transmittance up to 30%. Additionally condensation risk was significantly reduced.