Evaluation of the energy performance of Zero Energy residential Buildings: Complexity of dynamic simulations and results variability

Due to its energy and environmental impact, the building sector has become a challenging field in order to fulfil the need for energy renovation and obtain low-consumption buildings. The main issue, for those who approach the feasible design of a Zero Energy Building (ZEB), is to assess, in the most realistic way possible, the thermal and energy needs and the energy production of the building, properly considering all the possible variables. Through the analysis of a newly built residential building case study, this work aims at showing the complexity of the ZEB design, analysing the energy performance as the design choices vary. After characterizing envelope and systems components, potential variations in the model are highlighted by applying a set of updated climatic data, varying occupancy, shading systems and natural ventilation functioning, often neglected. It leads to a wide and differentiated range of results, consequently influenced by the design phase. The work aims at providing, in the definition of the energy performance of the building, an evaluation of the variations obtained from the variables analysed that in the modelling phase are normally considered as a boundary but which instead play a key role for achieving the ZEB objective.