CALCULATING U-VALUES IN LIGHT STEEL FRAMING - DEVELOPMENT OF A SIMPLIFIED METHOD

摘要

There has been considerable debate over the development of simplified calculations methods for thermal transmittance (U-values) for light steel frame constructions that designers can readily use. Such methods must accommodate the effects of non-homogenous layers and thermal bridges where the difference between the thermal conductivity of materials is large. Currently the method for calculating U-values set out in EN ISO 6946 does not cover walls where metal studs penetrate the insulation layer. This paper describes the development of a simplified method for calculating U-values of light steel frame constructions suitable for incorporation into U-value calculation software. The analysis process involved the use of finite element modelling of a variety of light steel frame constructions. The data from the finite element modelling was systematically compared with a number of proposed simplified calculation methods. Some of these were found to give good agreement with the results from the finite element modelling. The simplified calculation methods are described in the following text with graphs to show their level of accuracy.