Empirical power-law relationships for the Life Cycle Assessment of heat pump units

The application of life cycle thinking and the life cycle assessment method is becoming increasingly important in Europe, with the decarbonization targets set by the European Commission. Electric heat pumps (vapor compression) are considered one of the most promising solutions for reducing a building’s greenhouse gas emissions. Applying the life cycle assessment method could be challenging when only limited information are available. Reliable tools, for instance, power-law relationships, could be useful for the purpose. Power- law relationships were derived in this article to evaluate the environmental profile of electric heat pumps. 17 745 machines were cataloged according to data from the Italian database “Conto Termico”. 10 empirical relationships were created to correlate the mass of the appliance and the refrigerant content for different heat pump technologies (i.e., air-air, air water, brine-water, and water-water) and refrigerant gases (i.e., R410a, R134a, and R32). The power-law relationships are proven by considering 16 environmental impact categories, based on Environmental Footprint 3.1 EN 15804 method, using deterministic and stochastic approaches. The validation process shows that correlations related to heat pump manufacturing are reliable for all impact categories, while power-refrigerant gas correlations must be used more carefully as they are affected by a more significant error.