Conduction heat transfer through opaque envelope components is one of the parameters that characterize the thermal performance of buildings and its consequences in terms of energy consumption and thermal comfort. A building envelope can be thermally described by two parameters: thermal conductivity (λ) and heat capacity (ρ∙c). Estimating these thermal properties in situ allows the characterization of real building elements considering different aspects such as thermal behaviour under specific weather conditions, quality variability in materials, local construction technologies and material deterioration. This paper presents a method to estimate the thermal conductivity and volumetric heat capacity of a homogeneous element using a non-destructive test considering natural oscillations. Surface temperature and heat flow were measured in a concrete sample (with known thermal properties) and data was treated with a signal processing technique. Estimation is carried out with a heat and moisture transfer model. The measurements were performed on six days under different sky conditions over a month period, showing the importance of solar radiation as a heat source. Results gave acceptable estimations (average inaccuracy of 10-14%) of thermo-physical properties.
Non-destructive test; Thermo physical properties estimation; Heat and moisture simulation
