Is a Machine More Efficient Than the Hand? What are the washing-
up techniques that can transform a consumer from a carefree
dishwasher to a supereconomic one? In seeking to understand and
prevent global warming and other man-made environmental
problems, the energy consumption of household appliances has
come under close scrutiny. One household task—dishwashing—can be
accomplished by an appliance, by hand, or by some combination of
the two.To investigate the environmental effects of these
competing methods, I and a team of researchers from the
University of Bonn conducted a test comparing the energy
consumption and performance of manual dishwashing with that of
dishwashing machines. To rule out possible regional differences
in dishwashing techniques, we persuaded 113 people from seven
countries in Europe to participate in the dishwashing
experiment.We compared their use of water and energy and the
cleanliness they achieved to the consumption generated by two
energyefficient dishwashers.To reduce variability in