Hasse diagram technique - a useful tool for life cycle assessment of refrigerants

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Hasse diagram technique - a useful tool for life cycle assessment of refrigerants

Weckert, Monika / Restrepo, Guillermo / Gerstmann, Silke / Frank, Hartmut

Destruction of the polar ozone layer and global climate change are proven consequences of various man-made volatile compounds of which substances used for air-conditioning systems or refrigeration units are important contributors. The Montreal and Kyoto Protocol regulate the phase-out of ozone-depleting substances and the reduction of greenhouse gas emissions. In the present work, the main focus is laid on emissions from air-conditioning (A/C) systems depending on the used refrigerants, and the comparison of life cycle assessment (LCA) results by means of the Hasse Diagram Technique. Five refrigerants were ranked according to three parameters. Two Hasse Diagrams were drawn; one using the energy consumption during refrigerant production and compression of the refrigerants during operation of the A/C system, the other one additionally including the direct emissions during the total life cycle of the A/C system. According to this study, the refrigerants R152a and R290 have the smallest environmental impact. The two Hasse Diagrams clearly show that direct emissions of refrigerants are crucial within the life cycle of an A/C system. Due to its small GWP₁₀₀, carbon dioxide (R744) has a better direct emission balance than hydrofluorocarbons and hydrocarbons. Next to energy and emissions values, other properties (for instance, toxicology, safety, energy efficiency) are of importance when deciding which refrigerant can be recommended as substitute. But the more parameters are included, the more likely is it that incomparabilities in the Hasse Diagrams occur. Thus, when applying the Hasse Diagram Technique to LCA, not more than three parameters should be considered. Further studies are planned to examine the relative importance with respect to energy efficiency, environmental and human health of the various properties.