Is it a match? Smart home energy management technologies and user comfort practices in German multi-apartment buildings

Energy-savings from smart home technologies (SHT) are a topic of considerable debate: While proponents of SHT emphasise the potential to reduce heating energy consumption and facilitate energy flexibility, critics highlight real-world challenges and a lack of evidence of actual savings. This study provides insights into SHT's actual saving potential and reveals essential mechanisms of occupant-technology interaction. Based on social practice theory, this paper explores how occupants integrate SHT into their everyday comfort practices. Furthermore, it assesses the resulting impacts on heating energy consumption and compares these interactions to those within conventional building settings. The interactions with a pilot SHT are evaluated in 137 apartments in two newly constructed multi-apartment buildings. For comparison, a survey of households in conventional buildings, which vary in age, size and heating demand, is analysed. The case study employs a mixed-methods approach, based on standardised surveys, house tours, and measurement data, including metered energy consumption and indoor temperatures. The findings suggest that households in conventional German buildings have become accustomed to temperature variations within apartments. However, a preference for thermal variation appears to conflict with the dominant features of SHT, which, as this study implies, tend to produce more homogeneous indoor temperatures. The study identifies four distinct interaction patterns based on an in-depth analysis of heating comfort practices. These patterns vary in how well material settings align with comfort practices, ranging from low to high efficiency. The results indicate that SHT does not offer a 'matching' one-size-fits-all solution for residents' diverse needs and heating demands.