Experimental determination of the building envelope’s dynamic thermal characteristics in consideration of hygrothermal modelling – Assessment of methods and sources of uncertainty

Abstract

The characterization of the dynamic behavior of building opaque elements is essential to compare different design and refurbishment alternatives. Indeed, the building envelope’s dynamic response to external weather conditions can play a key role in the building energy performance. This is true especially for cooling dominated climates but also for colder climates, where highly insulated buildings can suffer from overheating due to poor dynamic responses. Analytical methods can be adopted only for elements with homogenous material layers and well-known properties. Consequently, experimental tests are the only viable solution for existing buildings or inhomogeneous walls. However, a reference procedure is missing, the number of researches on this topic is still limited, and several aspects have not yet been investigated in details. In this framework, this work aims to improve the accuracy of the experimental procedure to determine the dynamic thermal properties of opaque components from heat flux and temperature measurements in controlled environment. Starting from steady state and dynamic tests on a multilayered timber wall, a robust numerical model was developed and used to improve the design of the experimental apparatus and to assess the impact of humidity and uniformity of dynamic solicitations on the estimated dynamic parameters.