In particular, [PERSON] and [PERSON] [17] studied the energy and exergy performance of four low-GWP alternative refrigerants (R32, R452B, R454B and R466A) employed in a two-speed air-to-water heat pump and drew conclusions on the corresponding performance to provide space heating in cold climates: the systemic irreversibility of R452B and R454B are consistently lower than that of the other fluids at every compressor speed and external air temperature. [PERSON] et al. [18] developed an experimental setup to evaluate the efficiency of a refrigeration system adopting alternative fluids; under the tested conditions, the R454B fluid had slightly better performance and lower environmental impact than the other nontraditional candidates,i.e., R452B and R32. Similar experimental results were reported by [PERSON] et al. [19], who analyzed the working performance of R452B, R454B and R410A. The performance of R454B was similar (heating capacity from \(-8\%\) to \(-2\%\) lower, COP values from \(-0.9\%\) to \(+0.6\%\) higher) to that of R410A, with the advantage of a lower optimum refrigerant charge that, combined with a lower GWP, guarantees a significant reduction in direct CO\({}_{2}\) emissions. In addition, several results on fluids alternative to R410A have been obtained by numerical simulations [20; 21; 22; 23; 24; 25]. In particular, [PERSON] et al. [20] performed a theoretical screening of refrigerant mixtures subjected to a multiparameter optimization process consisting of GWP, flammability and thermodynamic parameters; starting from 12 pure refrigerants, the screening identified several mixtures fulfilling all the restrictions, which were promising to be used in applications with a GWP limit below 150. [PERSON] et al. [21] provided a global-warming impact analysis of environmentally friendly refrigerants used as replacements for R-134a and R-245 fa in medium- and high-temperature heat pumps by considering the emission factors of different countries. The results revealed that in addition to the GWP, the emission factor associated with the sources of electricity generation has a crucial impact on indirect emissions determining whether it is beneficial to employ alternative refrigerants in the heat pump systems. [PERSON] et al. [22] compared the performance of a new-mixture refrigerant, named RHR-1, with commonly used refrigerants including R-134a, R-410A, R-407C and R22, in terms of heating COP, compression ratio and discharging temperature. The new refrigerant, characterized by no ODP and by a GWP of 279, presented a COP in the range of 2.43-4.93, which was higher than other candidates in most design cases. [PERSON] et al. [23] conducted a parametric investigation of a heat pump operating with R-152A for different operating conditions: various ambient and indoor temperatures and different compressor rotational speeds. Data revealed that R-152A was found to be the most efficient refrigerant compared to natural refrigerants (R-600a and R-290), harmful refrigerants (R-134a and R-404A), as well as promising refrigerants (R32 and R-1234 yf). [PERSON] [24] calculated the seasonal energy performance of heat pumps that utilize alternative refrigerants following the standard EN 14825; R-425B and R-454B resulted as the most suitable fluids among the tested refrigerants. [PERSON] et al. [25] carried out a thermodynamic performance analysis, based on energy and exergy balances, of a geothermal heat pump employing either R-410A, R-32 or R-454B refrigerants. The obtained outcomes showed that R-454B was the optimal solution to replace R-410A, leading to a COP increase of up to 5% under different working conditions. Nevertheless, in the literature, there are still few studies quantifying the energy and environmental advantages of alternative refrigerants for air-source and ground-source heat pump systems.