The thermal resistance of retrofitted building components based on in-situ measurements

Syracuse, NY

Buildings are responsible for a large share of the worldwide energy use. For new buildings very strict objectives for the energy performance of buildings are set. The main energy use however occurs in existing buildings emphasizing the need for renovation of the older building stock. In order to detect deviations from the theoretical performance, in-situ measurements of the envelope performance after renovation can give insight in the workmanship and issues with different renovation techniques. Therefore, the focus of this paper is to determine the thermal resistance of building components from in-situ measurements, before and after renovation. Different methods were applied to examine the thermal resistance of the building components: the average method, linear regression, Anderlinds’ method, ARX modelling (Auto-Regressive models with eXogenous inputs) and Grey Box Modelling. All of these methods seem to lead to similar results with only a small variation in confidence intervals, except for linear regression, which couldn’t capture dynamic heat flows due to solar radiation. For the assessed exterior walls, different phenomena influencing the thermal resistance were noted. The measured thermal resistance answers the estimated theoretical value of the building components quite well before renovation, but after renovation the difference is variating due to cavity air flows.

https://surface.syr.edu/ibpc/2018/IM1/5