Recent legislative measures promote use of environmentally friendly refrigerants to mitigate global warming. Different environmental metrics are used to facilitate decision-making process of selection of refrigerant with low environmental impact. Total equivalent warming impact (TEWI) methodology is able to reflect the effect of heat pump or refrigeration system to global warming by accounting for both direct and indirect emissions associated with the refrigeration system. This paper extends TEWI methodology by using Global Temperature change Potential (GTP) metric instead of Global Warming Potential (GWP) one, which conventionally used to put different emissions on single CO2 scale. The analysis is done for the simple vapour compression heat pump system, where a number of refrigerants are compared. The study concludes with the analysis of applicability of modified TEWI analysis for further refrigerating system environmental assessment studies.