Energy performance of fire rated LSF walls under UK climate conditions

Light-gauge Steel Frame (LSF) systems, one of the emerging building practices can be susceptible for catastrophic failure in fire accidents and less energy efficient due to the high thermal conductance of Cold Formed (CF) steel elements and resulting thermal bridging effect. Apart from independent investigations and optimization on LSF walls against fire and energy performance, it is vital to build-up knowledge on energy performance of fire rated LSF walls. Therefore, a series of fire rated conventional and modular LSF wall panels, which covers a wide range of industrial practices in European countries, have been investigated for their thermal transmittance, U-Value in the present study. Firstly, Finite Element Models (FEM) for three LSF wall panels were developed and validated against previous results. Subsequently, these models were extended to analyse the U-Values of the parametric specimens. The results show that, the concepts of back-blocking panels and discontinuous insulation options account for only slight improvements of U-Value (3–5%). Moreover, the variation of U-Value with respect to the cavity insulation ratio is found to be quite interesting, that adding cavity insulation at very low Insulation Ratios (IR) like 0.2 to 0.4, a 40%–60% reduction in the U-Value is obtained while further increase in IR results in less than 10% U-Value reduction. Therefore, 0.2 to 0.4 IR is proposed for conventional and modular LSF walls for appreciable energy performance avoiding unnecessary compensation in terms of costs, weight of the structure and structural fire performance.