Active Thermal Method Applied to the In Situ Characterization of Insulating Materials in a Wall

Abstract

An in situ estimation of the thermal properties of bio-sourced building wall insulation components is of critical importance in improving both the energy efficiency of buildings and the development of construction materials with a smaller environmental footprint. Depending on weather conditions, passive methods are not always feasible; they require time to conduct lengthy testing and may lead to significant uncertainties. This article presents an active method based on power dissipation via flat electrical resistance. The method can be implemented regardless of outdoor weather conditions and is suitable for walls with high overall thermal resistance for which the small average component of the through flow is difficult to estimate. Measurements are conducted of both wall input flows and temperatures. An inverse method, derived from a finite difference model of 1D transfers along with a multi-objective approach, enables the characteristics of a two-material assembly to be identified. A multi-objective method was chosen to solve the problems of high correlation between the thermal parameters of the model. However, the method requires the use of two temperature sensors integrated inside the wall. Following a laboratory validation phase on a PVC/plasterboard assembly, the method is implemented on an actual wall. A coating/hemp concrete assembly is also characterized as part of this work program. The thermal conductivity of the hemp concrete block was estimated at 0.12 W m−1 K−1 and is consistent with values found in the literature.

Numerical and experimental analysis of building walls thermal performance

“…Their numerical results indicate that heat conduction is linked to the thermal properties of the substrates and the thickness of the walls. Biteau et al (2021) have developed an active method for the characterization of insulating materials, using finites differences method. The method was used on an insulated wall made of hemp concrete to conclude that the processing of the flux density and temperature data allowed the identification of the thermal properties of these materials.…”

Production of Particleboard Using Various Particle Size Hemp Shives as Filler

“…Research into the identification of energy loss, life cycle assessment for materials, improved durability standards, and the switch to more carbon-neutral materials is already in progress. [ 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. The use of plant-based ingredients and green biomass is an imminent alternative to timber resources and soon will be explored even more than in the past [ 10 , 11 , 12 ].…”