The paper studies the effect of different climate conditions (average, cold and warm European climate) on total lifetime global warming gas emissions of 30 kW (8.53 tons) capacity air/water heat pump systems designed for retrofitting of heating systems in European building sector applications. The analysis is performed for low GWP refrigerant selection with GWP values not greater than 150 (refrigerants R152a, R1234_yf, R290, R1270). The results are compared with R410A, which is used as a reference refrigerant. Indirect emissions are shown to dominate the total lifetime emissions of the heat pump system. The amount of indirect emissions is dependent on a number of parameters, including the heat pump system performance under various climate conditions. That affects the total lifetime emission of air/water heat pump systems at different locations.