Theoretical and actual energy behavior of a cost-optimal based Nearly-Zero Energy Building

Nowadays, Nearly-Zero Energy Buildings (NZEBs) seem to be the best solution to achieve the ambitious decarbonisation targets defined by the European Union for the building sector, thanks to the combination of performing envelope and efficient technological systems. In this framework, energy simulation proves to be an effective tool for the preliminary design phase, to evaluate different retrofit scenarios. Despite the high-quality performance of the simulations, theoretical consumptions result different from actual ones. The main reason for this discrepancy lies in the presence of the occupants and in their interaction with the energy systems, a factor that the energy simulation cannot fully capture. This paper aims to verify the gap between theoretical and actual values in a real NZEB located in the North of Italy. Ideal consumptions of this all-electric single-family house, resulting from energy certification and dynamic simulations, were compared with the real ones, coming from the electricity bill.