Potential energy saving and emissions reduction using propane in an air-to-water heat pump system for heating and cooling in residential and service buildings

As reported in the IEA's report "Energy Technology Perspectives: Scenarios & Strategies to 2050 - IEA 2010", considering the building sector it is expected that the global final energy demand will increase up to 60% and the CO2 emissions will be nearly doubled in 2050. Following the current trends, the global average temperature is expected to rise of 3.6°C in the long-term, as the World Energy Outlook 2014 shows. To reduce the environmental concerns related to the heating and cooling needs in the building sector, the heat pumps represent a valid option. Being the indirect emissions for these appliances over the 90% of the total one, the improvement of the performance is of primary importance combined to the use of low GWP refrigerants, as the natural ones. Here the potential energy savings and emissions reduction is presented for propane air-to-water heat pumps in comparison to HFC ones, for several final users (apartment block and school building) and climates (warm, cold and average). For a fixed climate condition, changing the fluid and the final user type, through the modeling of the heat pump balanced with the same bivalent temperature, the performance maps are carried out; hence, a model in TRNSYS allows the integration of the energy consumption over the whole year accounting for real climatic data. Finally, the energy consumptions are adjusted with a factor accounting for the partial load operation and the TEWI parameter is used to measure the reduction of the total environmental impact.