Energy and economic analysis of air-to-air heat pumps as an alternative to domestic gas boiler heating systems in the South of Italy

According to the electricity tariff recently issued by the Italian government for the domestic heating systems fed with heat pumps (HP), an energy and economic analysis was carried out with the aim of investigating the effectiveness of the air-to-air heat pump systems (HPS) as an alternative to the traditional heating using domestic gas boilers systems (GBS). For the purpose of this study, the apartments of three residential buildings were examined. The hourly heating loads were calculated with the ASHRAE radiant time series and the coefficient of performance (COP) of the HPs was evaluated for each operating condition. The costs for the heating system installation and electricity and/or gas bills were combined with the benefits, related to the current promoting tax credit program. The study turned out that the time when the GBS convenience surpasses the HPS mainly depends on the amount of thermal energy consumed in the year, although other important features, such as the domestic electricity consumption and the kind of energy used to supply the domestic hot water system and the cookers, play a relevant role in making the best choice between HPS and GBS.