Experimental assessment of wall thermal properties using an integrated response factor approach

Accurate determination of thermal parameters in building envelope components is crucial for evaluating energy performance. While response factor theory has been applied to accelerate the experimental characterization of steady-state thermal properties such as the U-value, periodic thermal properties remain underexplored despite their growing relevance due to global warming. This study presents a novel model based on response factor theory to characterize the unitary heat flux on the opposite side of a pulse solicitation as a function of time and four key parameters. A unified testing methodology is proposed, enabling simultaneous characterization of stationary and periodic thermal properties through a single hot box experiment. Key aspects of the setup, testing protocol, and data processing are detailed. The method was first validated via numerical simulations. Simulations, performed using a Finite Element Method, demonstrate the high accuracy of the proposed method in estimating both stationary and periodic thermal parameters with deviations under 5 %. The method also showed resilience to boundary condition noise (mainly below ± 10 %). Following on from this point, experimental validation on an insulated wall confirmed the approach’s effectiveness, with deviations under 10 % compared to traditional decoupled methods. This approach offers a streamlined pathway for standardized thermal characterization assessment.