Lightweight steel-framed thermal bridges mitigation strategies: A parametric study

In building applications (e.g. industrial, offices and residential), the use of lightweight steel-framed structural elements is increasing given its advantages, such as exceptional strength-to-weight relation, great potential for recycling and reuse, humidity shape stability, easy prefabrication and rapid on-site erection. However, the high thermal conductivity of steel presents a drawback, which may lead to thermal bridges if not well designed and executed. Furthermore, given the high number of steel profiles and its reduced thickness, it is not an easy task to accurately predict its thermal performance in laboratory and even less in situ. In a previous article, the authors studied the importance of flaking heat loss in lightweight steel-framed walls. This article discusses several thermal bridges mitigation strategies to improve a lightweight steel-framed wall model, which increase its thermal performance and reduce the energy consumption. The implementation of those mitigation strategies leads to a reduction of 8.3% in the U-value, comparatively to the reference case. An optimization of the wall module insulation layers is also performed (e.g. making use of new insulation materials: aerogel and vacuum insulation panels), which combined with the mitigation approaches allows a decrease of 68% in the U-value, also relatively to the reference case. Some design rules for lightweight steel-framed elements are also presented.