This thesis focuses on the research and analysis of a real case study in Denmark. The house in question is part of a European project called PRELUDE (Prescient building Operation Utilising Real Time data for Energy Dynamic Optimisation) and represents a building with high-level technological solutions. The building is classified as an NZEB (Nearly Zero Energy Building) for its energy performance and use of renewable energy resources. These types of buildings, despite being equipped with many energy efficiency solutions, do not perform as expected, and they often demonstrate the highest energy performance gap. So, thanks to measurements and modelling, it could be possible to know whether the selected buildings underperform and to identify the most impactful parameters.