The co-heating test as a means to evaluate the efficiency of thermal retrofit measures applied on residential buildings

Syracuse, NY

In order to reduce the energy use of residential buildings, regional governments in Belgium established, amongst others, mandatory criteria for the energy performance to be achieved after retrofitting. However, due to construction deficiencies, deviating boundary conditions, and nonmodeled physical phenomena and interactions, the actual energy performance may differ significantly from theoretical design value. Several studies indicate this as the performance gap. This paper focuses on analyzing the actual impact of the refurbishment measures applied to a single-family home in Belgium. Hereto, in-situ measurements assessing the building envelope’s thermal performance, described by the overall heat loss coefficient HLC [W/K], are performed both before and after the retrofit. To analyze this HLC, a quasi-steady state test, the so-called co-heating test, has been performed before and after renovation of a single-family home in Belgium, renovated to the nearly Zero Energy Building (nZEB) level. As a result, the HLC determined with linear regression and an Auto-Regressive model with eXogenous inputs (ARX) show similar estimates, except for a smaller confidence interval for the ARX. Furthermore, it is shown that data set lengths shorter than 10 days are quite sensitive to sample times. For our case study, the gap between the theoretical and measured HLC enlarges after retrofit. Finally, the influence of a unheated neighboring zone on the HLC is assessed.

https://surface.syr.edu/ibpc/2018/IM1/4