Experimental assessment of thermal break strips performance in load-bearing and non-load-bearing LSF walls

Abstract

A reliable evaluation of thermal behaviour and energy efficiency of buildings depends on the accurate thermal characterization of the envelope components. One of the most reliable methodologies to perform this thermal characterization is the measurements under laboratory-controlled conditions. The thermal performance assessment of lightweight steel-framed (LSF) building components exhibits particular additional challenges related to the strong thermal conductivity contrast between cavity insulation and steel frame materials, which may originate unwanted significant thermal bridge effects. The use of thermal break (TB) strips is one of the most currently used thermal bridge mitigation strategies. It was not found in the literature any experimental campaign for TB strips thermal performance evaluation in LSF elements. In this paper the thermal performance of twenty load-bearing (LB) and non-load-bearing (NLB) LSF walls configurations are measured, using the heat flow meter (HFM) method under controlled laboratory conditions. Three thermal break (TB) strip materials and three TB strip locations in the steel stud flanges are assessed. It was found that the inner and outer TB strips show very similar thermal performances, while double TB strips have a relative significant thermal performance increase. Aerogel was the best performance TB material, exhibiting a substantial improvement relatively to recycled rubber and cork/rubber composite TB strips. Furthermore, the TB strips performance was identical for the evaluated structural (LB) and non-structural (NLB) LSF walls.