Performance gap and occupant behavior - Review and analysis of high-efficiency residential buildings in Germany

The building sector is responsible for about 40 % of the EU primary energy consumption. For this reason, the EU and its member states have constantly strengthened energy legislation, such as implementing the Energy Building Performance Directive (EPBD) and the German Energy Saving Ordinance (EnEV). While on the one hand, the energy efficiency of buildings is continuously improving, on the other hand, there is often a significant gap in energy performance between the targeted values according to code calculations and simulations from design stages and real operation. In addition to inefficient operation or poor construction of the building and building systems, this is mainly attributed to occupant behavior (OB). The aim of this research paper is to present a broad overview of the different types of energy performance gaps in the literature. The focus beyond this is on the energy performance gap (EPG) of low-energy and "nearly zero energy buildings (nZEB)", in connection with occupant behavior and the underlying causes of the observed deviations in residential buildings. To this end, one high-efficiency residential building with eight apartments is examined and analyzed as a case study. Comparisons are made between the code compliance calculations, simulations with different occupant behaviors, and real measurements from Technical Monitoring (TMon). Several factors are eliminated in order to be able to evaluate the actual deviation by occupant behavior more precisely. The study considers thermal energy for space heating and domestic hot water, as well as electricity usage.