There are several European studies that indicate dishwashing machines are more energy and water efficient than manual dishwashing during their use phase. Energy Star suggests that annually, dishwashers save a household $40 worth of energy and use 5,000 less gallons of water. However, a complete comparative Life Cycle Assessment between both dishwashing methods is yet to be conducted. This study intends to calculate the environmental impact of manual and machine dishwashing in residential American households. For example, an environmental impact such as kg CO2 equivalents produced from all phases of the life cycle can be modeled.
An important aspect to be modeled is how impacts can change with geographic region. Cities across the United States have electrical grids with different compositions of renewable and nonrenewable energy. Cities also have varying water resources; a city in the Southwest has limited water resources compared to a city in the Northeast. Furthermore, the behaviors of manual dishwashing may be linked with geographic location as well. From European studies, global behaviors like washing dishes under running tap and in a water-filled sink have been observed.
Several scenarios for the use phase will be compared in this study. The use phase of the life cycle depends on geographic location as well factors such as the water heater. This study intends to compare electric and natural gas water heaters of different ages (efficiencies). Two different types of dishwashers will be tested. One is a Whirlpool global wash system and the other is a Kitchen Aid Rotating Intlet Filter (RIF) system. These washing machines have two different mechanisms for using and distributing water within the dishwasher. Finally, in order to make the study more robust, manual dishwashing behaviors will be tested in a laboratory setting that follows AHAM and ANSI procedures for testing commercial dishwashers. Participant’s behaviours will be observed and their cleaning performance will be recorded. It is expected that different archetypes of manual dishwashers will be observed such as people who try to save resources and people who are indifferent to how much they are using .
In conclusion, this study aims to model several use phase scenarios for manual and machine dishwashing in at least two different U.S. cities. These scenarios will be compared on the basis of environmental impacts as well as cleaning performance, water use, and energy use.