An experimental and forecast-driven Expanded Total Equivalent Warming Impact analysis of a water-to-water heat pump operated with R-1234yf-based fluids

• R-1234yf-based fluids cut first-year CO 2eq emissions by 30–50 % compared to R-134a. • High emission factor scenarios decrease the advantages of innovative refrigerants. • Low cooling efficiency might impact low-GWP fluids in the future. • Forecasting the future building requirements reduces lifetime emissions by 7–25 %. Heating, cooling, air conditioning, and ventilation systems are major contributors to global warming emissions and climate change. As global temperatures rise, building requirements evolve, with cooling expected to play an increasingly important role. Seeking sustainable options for this growing demand, this study presents an experimental comparison of four refrigerants (R-1234yf, R-513A, R-516A, R-134a) in a water-to-water heat pump within a dynamically simulated residential building. The environmental performance is evaluated using the Expanded Total Equivalent Warming Impact index through a novel dynamic forecasting model. This methodology integrates time-varying parameters alongside forecasts of carbon dioxide emission factors for electricity production in Italy and thermal and cooling energy needs to assess first-year and lifetime environmental impact comprehensively. First-year results show that low Global Warming Potential refrigerants ensure a reduction of total emissions between 30 % and 50 % compared to R-134a. Furthermore, a sensitivity analysis reveals how varying energy production scenarios could influence these benefits, with countries with high renewable energy capacity being further advantaged. Lifetime projections indicate substantial emission reductions (over 60 % for R-1234yf, 36 % for R-513A, and 50 % for R-516A) compared to traditional evaluations. However, lower cooling performance and efficiency degradation significantly impact low-GWP refrigerants, potentially increasing indirect emissions in the future. Overall, this novel dynamic forecasting model estimates 7 % to 18 % lower lifetime emissions than conventional assessments.