Inverse estimation of the annual heat flux through the internal surface of a multilayer wall in an occupied prefabricated house from field measurements

Understanding transient heat transfer in building assemblies is important for improving the energy efficiency of the built environment. This paper describes an inverse analysis to evaluate the field energy performance of a multilayer prefabricated wall. The purpose is to estimate the heat flux through the internal surface of a wall in an occupied lightweight house in Quebec City (Canada). The inverse problem modeling was based on one-year on-site temperature measurements which convey the in-use thermal behavior of the wall assembly. The inner surface experienced an outward heat flux for most of the year. The greatest heat loss was around 5.5 W m −2 in winter and the greatest heat gain was around 1.0 W m −2 in summer. In the heating period, the indoor environment lost about 18 kW h m −2 (6.5 × 10 7 J m −2 ) of thermal energy. There was a total thermal gain of around 1 kW h m −2 (3.5 × 10 6 J m −2 ) during the free cooling period. Based on the heat flux estimations, the effective thermal resistance of the assembly was found to be 6% lower than its theoretical value, but still in compliance with Canadian building standards. • The inner wall surface experienced heat losses for most of the year monitored. • Heat loss and heat gain peaks were around 5.5 W m −2 and 1.0 W m −2 , respectively. • 18 kW h m −2 of thermal energy left indoors across the wall in the heating period. • 1 kW h m −2 of thermal energy entered indoors across the wall in the cooling period. • Effective R -value is 6% lower than the theoretical one and complies with the norms.