Theoretical, numerical and experimental studies on thermal insulation performance of different cross laminated timber walls

Cross laminated timber (CLT) is recognized as alternative to traditional building materials, which is mainly used as wall or floor of buildings. The heat transfer coefficient of wall is an important indicator of building energy saving, but there are relatively few studies on it of CLT wall. This paper mainly studied on the thermal performance of CLT walls by experiments, theoretical formulae and simulation. Based on hot box-heat flux method, the heat transfer coefficient values of CLT walls were measured and the influence of wall structure and thermal insulation materials were analyzed. Then, the heat transfer coefficient of different CLT walls was predicted by theoretical calculation and theoretical methods were compared based on calculation results. Finally, the temperature distribution, heat flux distribution and heat transfer coefficient of CLT wall were simulated and the applicable climate regions of CLT wall were proposed. The results showed that the double-layer structure or hollow structure had little effect on the heat transfer coefficient of CLT wall. The heat transfer coefficient of CLT wall significantly reduced by 37%-50% after adding internal or external thermal insulation materials. The lowest heat transfer coefficient of CLT walls in this study was 0.278 W/(m2*K). The arithmetic mean relative error of composite method is lower than the parallel-path method and the isothermal planes method, which was 6.38%. And the arithmetic mean relative error of heat transfer coefficient between simulation and experiment results was 7.46%. Thermal bridge structures in buildings, such as corners and partitions, will bring about 35%-38% increasement in heat transfer coefficient. These findings should be able to provide scientific basis for the use of CLT buildings in different cold regions.