## 3 Results and Discussion
As all proposed refrigerants alternative to R134a and R245 fa have lower GWP values, the energy efficiency analysis can determine the TEWI/Q of the system. A higher COP of a refrigerant can guarantee a lower TEWI/Q. The reason for this is that the proposed alternatives have lower direct emissions due to their lower GWPs. In comparison, higher COPs can lead to lower indirect emissions as this parameter is inversely proportional to the system's energy efficiency. The comparison between the heating capacity and TEWI of the alternative refrigerants and the reference GHGs including R134a and R245 fa, is presented in Figure 8. In the MTHP application, R290 provides a 45% greater heating capacity than R134a under the same operating condition (DT = 50 \({}^{\circ}\)C), but the utilization of R290 increases the TEWI by 16-45%, in selected countries. The TEWI of R1234 yf is very close to the TEWI of R134a, except in Sweden, where the TEWI of R1234 yf is 30% lower than R134a. Interestingly, R513A provides an 8% lower TEWI and a 4% higher heating capacity in Sweden, which is the only case among all tested refrigerants and selected countries. A reduction in TEWI accompanies the increment in heating capacity compared to R134a. Although R1234 ze(E) and R450 have lower TEWI than R134a, they also provided 15-26% lower heating capacity. In the HTTP application, R600 provides the highest heating capacity, which is 24% greater than R245 fa. A TEWI increment between 10 and 26% is expected in selected countries when using this refrigerant. The lowest TEWI belongs to R1336 mzz(Z), accompanied by the lowest heating capacity compared to other refrigerants. The heating capacity of R1336 mzz(Z) is 32% lower than R245 fa and its TEWI decreases between 45 and 53% compared to the reference refrigerant. R1234 ze(Z) provides an 11% higher heating capacity than R245 fa, but its TEWI is 7-10% higher in the selected countries, except in Sweden. A reduction in TEWI by 2% is found in Sweden, making it the only case with a higher heating capacity, accompanied by a lower TEWI than R245 fa. Meanwhile, R1234 yd and R1233 zd(E) each provide a lower TEWI and heating capacity than R245 fa. Figure 6: TEWI/Q of the MTHP application using R134a and its alternatives in (**a**) Brazil, (**b**) Sweden, (**c**) Canada and (**d**) Poland. R134a and R245 fa in MTHP and HTTP applications. Although the alternative refrigerants have lower GWP and consequently lower direct emissions than the reference refrigerants, the indirect emissions have a crucial impact on TEWI. It means that the COP of the RACHP system is critical, as it is inversely proportional to the indirect emissions. When the COP of the reference refrigerants (R134a and R245 fa in this study) is higher than their alternatives, as there is a particular value for \(\beta\), at which higher values mean that the TEWI of an alternative refrigerant is greater than the reference refrigerant. Therefore, for a RACHP system to benefit from utilizing alternative refrigerants to mitigate warming impact, the \(\beta\) value should be lower than the critical one. For instance, R1234 yf has the lowest critical \(\beta\) value among the alternative refrigerants compared to R134a. This means that the value of \(\beta\) should be below 0.09 kgCO\({}_{2}\)-eq. kWh\({}^{-1}\) to have a lower TEWI than R134a. This is due to the lowest COP of R1234 yf compared to other low-GWP alternative refrigerants. The highest critical \(\beta\) belongs to R290 as it has a higher COP than other alternative refrigerants. For this case, the critical \(\beta\) is found to be 0.63 kgCO\({}_{2}\)-eq. kWh\({}^{-1}\). For alternative refrigerants to R245 fa, there is not any critical \(\beta\) for R1336 mzz(Z), R1233 zd(E) and R1234 ze(Z) as these three refrigerants have higher COP and lower GWP than R245 fa. This means that both direct and indirect emissions decrease using R1336 mzz(Z), R1233 zd(E) and R1234 ze(Z) at any \(\beta\) value.