Two opposing trends are observed in Europe: an increase in the washing machines' rated capacity and a decrease of the household size (hence a decrease of laundry that has to be washed). The question poses: what kind of behavior is necessary to use the washing machines with a higher rated capacity in a more sustainable manner? To answer this question, a model of a washing machine (virtual washing machine) that is based on real data of real-life washing machines is constructed. Furthermore, a model that reproduces, to some extent, the household's washing behavior (virtual washing household) is developed.
By conducting parallel simulations of the usage of the virtual washing machine by the virtual washing households and by varying device-, household- and behavioral parameters, an optimal parameter combination with the lowest environmental impact is determined.
The basis for the virtual washing machine is the data gained by testing nine washing machines of different rated capacity (5 kg, 6 kg, 7 kg, 8 kg and 11 kg). All tests are conducted in accordance with EN60456:2005, with some modifications regarding the washing temperatures, load size and detergent dosage.
The predicting power of the virtual washing machine can be considered as good, given that there are numerous differences in tested washing machines.
The virtual washing household is designed in such a manner that a washing cycle is conducted when the household has enough laundry collected, so that the rated capacity of the washing machine can be used. It also offers a possibility to conduct an "emergency washing cycle" when the time needed for accumulating enough laundry (to use rated capacity of the washing machine) exceeds the waiting time acceptable by the consumer (so-called "maximal laundry waiting time").