In this paper an example of a "nearly-zero-energy building" in northern Italy is presented. A critical analysis of the technologies design, both for increasing energy efficiency and renewable energy production is carried out. The available data from an energy monitoring campaign during the seasons 2010-2011 and 2011-2012 are presented and discussed in order to evaluate the real energy performance of the building. The data of the monitoring campaign are also used to assess the real operational conditions of the building in order to perform a tailored energy calculation. Thus the calculation is performed using both monthly quasi-steady-state method and an hourly dynamic model. The simulation results are compared with the real building energy monitored data to get a "validation" of the model