Dynamic modelling and thermoeconomic analysis for the energy refurbishment of the Italian building sector: Case study for the “Superbonus 110 %” funding strategy

Abstract

• Development of a dynamic model simulating the thermal load for space heating of a building located in different weather zones. • Analysis of the thermostatic valve control applied to the emitters of the heating system. • Analysis of the refurbishment solutions applied in several combinations to the buildings considered. • The dynamic analysis of the CO2 heat pump reveals interesting perspective for the energy transition scenarios. • The thermoeconomic analysis shows a great economic profitability when the “Superbonus 110%” incentive is considered. The refurbishment of the building sector is a relevant issue in several Countries, such as Italy, where the poor energy performance of residential buildings dramatically affects the overall primary energy consumption and the related emissions of CO 2 . Such buildings are featured by a significantly poor efficiency of the conventional centralized boilers and by a scarce thermal insulation of the envelope. Therefore, the use of renewable technologies, as the solar ones, may significantly reduce the environmental impact of such residential buildings. Moreover, the use of modern and highly efficient boilers is crucial to reduce the primary energy consumption. The combination of these solutions along with the improvement of thermal insulation of the building envelope seems very promising to enhance the energy performance of existing residential buildings. In particular, this work proposes the integration of a CO 2 heat pump to replace a conventional gas-fired boiler. This solution aims to be suitable for the Italian economic funding policy, known as “ Superbonus 110%”, where some specific energy refurbishment actions are fully funded by the Government. In the layout presented in this paper, the existing radiators are supplied by a new CO 2 heat pump, since its high outlet temperature is very close to the boiler one. Furthermore, the thermal insulation of the building envelope and the use of photovoltaic panels are also considered in combination with the CO 2 heat pump. In this work, the dynamic, monthly, and annual results of the carried out dynamic simulations are then presented and discussed. The optimal solution of the proposed layout is detected by means of a detailed sensitivity analysis which considers different weather zones. The energy and environmental analyses show that the CO 2 heat pump coupled with all the other solutions leads to a reduction of the primary energy consumption by 52% and a total CO 2 emission savings of 49%. The Italian incentive is considered in the economic analysis and results show a Net Present Value of the investment of roughly 27 k€, considering a lifespan of 25 years.