Water- and Energy-Efficient Appliances for Circular Water Economy: Conceptual Framework Development and Analysis of Greenhouse Gas Emissions and Water Consumption

The concept of circular water economy has emerged for the sustainable and resilient use of water and for mitigating attendant greenhouse gas (GHG) emissions. Although macroscale circular water economy has been widely addressed, analysis of microscale household circular water economy, including water–energy nexus aspects, has not been thoroughly developed and documented. In this study, we quantify the contribution of household water and energy use to water consumption and GHG emissions. We develop a comprehensive spreadsheet-based input–output model to calculate the net GHG emission expressed as carbon dioxide equivalent (CO2e) and water consumption levels of household appliances for various supply- and demand-side scenarios. We quantitatively evaluate the impact of temporally and spatially varying emission factors of energy production on the GHG emissions and water consumption for a model household that employs appliances with various efficiency levels. To advance the concept of a circular water economy, we develop a framework for considering water reduction, reuse, recycling, and recovery, along with retrofitting/remanufacturing of water and energy appliances and fixtures. Finally, we illustrate the choices in household water and energy systems through a trade-off analysis based on the capital and annual costs of each appliance.