An insight into environmental footprints of emerging air-conditioning systems towards sustainable cities

Abstract

In this study, the environmental impacts of six conventional and modern air conditioning systems, including vapor-compression air conditioning (VAC), hybrid membrane-based air conditioning (HMBAC), desiccant enhanced evaporative air conditioning (DEVap), solar HMBAC, solar DEVap, and inverter VAC, are analyzed using a cradle-to-gate life cycle assessment (LCA) approach. The assessment is based on climate change, ozone depletion, terrestrial acidification, freshwater eutrophication, human toxicity, photochemical oxidant formation, ecotoxicity, water depletion, and fossil fuel depletion impacts. The LCA findings reveal that membrane-based systems (HMBAC and DEVap) are highly environmentally-friendly in comparison to the regular VAC systems (household split coolers), showing the capability of membranes in developing efficient air conditioning systems. In addition, solar-assisted systems reduce seven out of eleven environmental impacts, while they cause severe eutrophication, marine and freshwater ecotoxicity, and human toxicity consequences. Furthermore, it is unveiled that the inverter can reduce up to 38% of the environmental impacts of VAC systems which are the most common air conditioning system in buildings. Therefore, the manipulation of the inverter system in VACs can be considered as one of the short-term solutions in reducing the environmental footprints of air conditioning. Finally, the sensitivity analysis is applied to show the reliability of the outcomes.