Cradle-to-grave life cycle assessment of an air to water heat pump: Case study for the Lebanese context and comparison with solar and conventional electric water heaters for residential application

Abstract

This study investigates the environmental performance of the air source heat pump (ASHP) technology. The life cycle assessment (LCA) methodology is used. An LCA analysis provides a clear understanding of the environmental impacts of a product throughout its life cycle. This paper aims to i) determine and analyze the environmental impacts of the ASHP and ii) compare the impacts of the ASHP with those associated with a flat plate (FP) solar water heater (SWH) and a conventional electric water heater (CEWH). The functional unit is “heating 416,100 L of water to 60 °C”. The software used is SimaPro and the impact assessment method is IMPACT 2002+. Results show that the copper pipes of the ASHP are the highest contributors to 6 out of 15 impact categories for the assembly. Moreover, the refrigerant inside the pump is the highest contributor to ozone layer depletion (90.25%). The life cycle results of the three systems show a large contribution of the use phase to the total life cycle impacts. This leads to a need for improving the refrigerant, the Lebanese electricity grid and if possible changing the material of the heat pump pipes. The comparative LCA proves that the ASHP is the best alternative due to its low power requirement during the use phase: Lebanese households could save 1668.45 kg CO2 eq and 16983.25 kg CO2 eq by installing an ASHP instead of the solar water heater and the electric water heater, respectively. This work encourages installations of this better alternative across Lebanon's residential sector and in the world in order to mitigate the harm to the environment and further improve the use of renewable energy.