Assessment of energy consumption and CO2 emissions of residential buildings in the city of Padua

The Italian building stock is one of the oldest in Europe: 74% of the residential buildings have been built before the ‘80s. These buildings were not designed to satisfy today’s energy performance standards. The low energy efficiency results into high energy consumption and high environmental impact: 40% of the national CO2 emissions are linked to residential buildings’ space heating and cooling demands. These data highlight the importance of renovating the existing building stock, in order to reduce the carbon footprint of the country and to reach the national and European climate goals. In this context, this master thesis focuses on the analysis of the energy consumption of a sample of 1001 residential buildings located in Padua (Italy) under different retrofit scenarios. An urban building energy model (EUReCA) was used to simulate the buildings of the case study and the resulting model was calibrated using metered gas consumption data. The thesis presents three different renovation scenarios:(i) retrofit of the building envelope only; (ii) retrofit of the building envelope and replacement of the gas boiler with air source heat pumps and (iii) the same with additional installation of rooftop PV panels. This study quantifies the environmental benefits achieved thanks to these interventions, by comparing final and primary energy consumption and CO2 emissions before and after their implementation. Additionally, an economic analysis was conducted to assess the feasibility of the interventions, taking into account initial costs and payback time. The results show that prioritizing deep renovation (scenario iii) in the condominiums with highest consumption allows us to achieve the environmental targets in a cost-effective way. For instance, the primary energy reduction target set by the latest Green Buildings Directive can be reached by renovating only 123 buildings with an overall investment of approximately 68 M€, which is 18-48% lower than the cost of the other scenarios. The deepest renovation scenario on all buildings allows reducing CO2 emissions by 69% compared to the base case.