Is stochastic grey-box modelling suited for physical properties estimation of building components from on-site measurements?

Abstract

In current energy requirements, the thermal performance of buildings is assessed with simplified energy models. A performance label is calculated based on thermal properties of the constituent components of the building envelope. These properties, however, do not include factors such as workmanship issues, or moisture or airflow influences which might affect the thermal performance as designed. To have a better view on the actual thermal quality of building components, a reliable thermal characterisation method of building components on-site is required. The typically used semi-stationary measurement methods have an application that is seasonally bounded or can require long measurement periods. Because of these drawbacks, dynamic parameter estimation methods have gained interest. In this article, the physical interpretability of a typical stochastic grey-box model used to thermally characterise building components is assessed. The identifiability of this model structure is examined by observing the profile likelihood of its parameters for typical measurements. The results allow identification of the extent to which models can estimate the thermal properties of building components in a robust way. A comparison of both analyses allows to define indications for physically interpretable parameters.