Dynamic Thermal Performance Measurements of Residential Wall Systems

Abstract

The use of a hot box apparatus allows for thermal performance testing of a specimen in both static and dynamic regimes. In the static (steady-state) regime, the thermal conductivity or R-value of a specimen can be obtained. In comparison, the specific heat capacity and thermal diffusivity data can be obtained during the transient regime. Additionally, if heat flux pads are employed in the hot box apparatus, it is possible to monitor the energy that passes through a specimen during thermal cycling. In the case of wall systems, it is of interest to compare the thermal performance of one system against another for the purpose of selecting suitable energy efficient structures. However, the nature of this comparison is not as simple as it would seem. In this study, the thermal performance of several wall systems were compared to evaluate their energy efficiencies relative to one another. Under steady-state conditions, it is valid to simply compare the R-values against one another assuming equivalent measurement conditions. However, we are actually interested in the real-world performance of these systems, and in this case, the comparison of R-values is not sufficient to fully characterize differences in actual thermal performance. For this reason, a 24-h cyclic thermal loading was employed that mimicked a day/night cycle. By measuring the energy transmitted through the wall, the energy required to maintain thermal comfort could be determined. This study aims to characterize the real-world thermal performance of several systems by using this method.