Performance indicators of District Heating Systems in Italy - Insights from a data analysis

District Heating Systems (DHS) are a solution for the supply of heating and cooling in urban areas. Thanks to the possibility of exploiting multiple energy sources, a well-designed and well-operated DHS can allow primary energy savings, CO2 emissions reduction and integration of renewable energy sources for the heat generation. However, each DHS has its own peculiarities and its conversion and distribution efficiency is affected by several factors, including design parameters as well as operational choices and potential unexpected behaviours. Performance indicators calculated on a statistically relevant set of DHS can provide useful insights on their range of variability. This paper analyzes the performance of several DHS, by calculating the primary energy factor and the CO2 emission factor of the heat supplied to the users, using the current methodology defined by the European Standards. The results show that the efficiency of DHS is mainly affected by the energy source and the conversion technologies, but also the network losses have a crucial impact on the overall performance. The majority of the DHS included in this analysis supply heat to the users with a primary energy factor in the range 0.9-1.8 and a CO2 emission factor between 0 and 0.30 kg/kWh. The operation of Combined Heat and Power generation units connected to DHS needs to be analyzed with reference to the characteristics of the electricity available on the National Power Grid.