Investigation of heating energy performance gap (EPG) in design and operation stages of residential buildings

The Energy Performance Gap (EPG) in buildings is a recognized phenomenon. However, its definition and underlying factors are extensive, necessitating a thorough investigation of the quantitative impact of each factor contributing to the EPG. In this research, a calibration-based approach is employed to identify and measure the contribution of these factors. Questionnaires, measurements, analyses, and calibrations are conducted on the energy performance of four residential units of an apartment block building in Iran as a case study. Subsequently, the impact rates of three key causes of the EPG, namely heating system efficiency, weather data in an EnergyPlus Weather (EPW) format file, and occupant behavior, are determined. By incorporating these causes into the model calibration process, the disparities between the design and operation stages are decreased. The study highlights the significance and quantifiable effects of accurate and measured boiler efficiency, utilizing a genuine EPW file rather than a convenient EPW file e.g., airport stations, and adopting precise and adaptable assumptions for occupant behavior modeling in bridging the EPG between the design and operation stages. There are a number of factors that impact the design stage gap, including boiler efficiency, occupant behavior, and a corrected EPW file, which contribute 43.9%, 26%, and 6.6%, respectively.