LAUSR

Abstract The thermal performance of wall materials has a profound influence on the energy consumption and thermal comfort of the buildings. The thermal performance can be evaluated by various indexes, such as thermal conductivity, decrement factor, delay time lag, etc., which are obtained by different methods. To more comprehensively characterize the thermal insulation performance of wall materials, a thermal inertia factor was proposed in this study based on the temperature fields of the wall materials. The autoclaved aerated concrete (AAC) panels with different densities and thicknesses were prepared, and also a kind of AAC - calcium silicate board (CSB) composite sandwich wall panels were designed to be compared. It was found that the low density (i.e. low thermal conductivity) alone did not equivalent to high thermal inertia, that is, both the decrement factor and the time lag were proportional to the density of the panels. Thickening of the AAC panels significantly hindered the heat transfer, and the designed sandwich structure also had this enhanced hindering effect. The thermal inertia factor was calculated based on the simulations of temperature fields by ANSYS software. It was concluded that the comprehensive thermal inertia of AAC panels was favorable when the density of AAC was in the range of 700–900 kg/m3. The heat flux through the AAC panels reached equilibrium at a position of 55%–75% panel thickness away from the high-temperature surface facing the hot box. These achievements contribute to better understanding of the thermal insulation performance of AAC and are desirable for proper modeling and design of AAC or other insulation materials.