Valutazioni energetico – ambientali ed economiche di interventi volti a riqualificare un edificio pubblico secondo il target nZEB

The work was carried out from the hypothesis to rehabilitate a case study building, representative of the public tertiary stock, by assessing a set of retrofit actions aimed to improve the building energy performance toward nZEB (nearly Zero Energy Buildings) requirements. The building chosen as a case study is among those constituting the Città Studi Campus of the Politecnico di Milano university. The different hypotheses of improvement, regarding both building envelope and plants, have been considered in terms of energy (the evaluation of the building energy performance was carried out through the simulation code TRNSYS), costs and greenhouse gas emissions. The results of the study show that it is possible to reduce primary energy demand (and associated greenhouse gas emissions) at the 40% of the present by adopting widespread and proven technological solutions for retrofit; further, with the use of renewable energy sources produced on-site (in this case by means of a photovoltaic system) the net energy consumption can be near to zero. However, the economic analyzes highlighted the criticalities related to the implementation of some solutions, since the increased levels of insulation of the building envelope consistently with the current standards and the installation of the ventilation system with heat recovery are not cost-effective.