Application of hourly dynamic method for nZEB buildings in Italian context: analysis and comparisons in national calculation procedure framework

The Energy Performance of Buildings Directive (EPBD 2018/844/EU) requires to Member States to upgrade the methodology for the energy performance assessment of buildings. The current calculation method, based on the monthly quasi steady state calculation procedure, could be replaced in the next years by an hourly dynamic calculation procedure (EN ISO 52016), in which a resistance-capacity (RC) model is implemented to consider with more accuracy the heat exchange through the building envelope. In this framework, the present work aims at analysing and comparing the energy needs of three reference case studies of nearly Zero Energy Buildings (nZEB), applying both calculation procedures in order to investigate the main difference of the two approaches. Two residential buildings and one office, compliant with Italian minimum requirements for nZEB, were defined, and several energy simulations were carried out for all different climatic zones of Italian territory. Preliminary results highlighted significant differences of energy need mainly due to different weight of heat loss and heat gains obtained with the two considered calculation methods. This paper represents a preliminary study, but further analysis are recommended in order to evaluate the overall energy use for different type and different operation profile of buildings.