In order to simulate the usage of washing machines by the consumer, a concept of a “virtual washing household” is developed that, to some extent, behaves as a real life household. As essential part of this virtual household is the virtual washing machine in which washing cycles are conducted in dependence of the washing parameters, household size and behavioral parameters. The concept stipulates that a washing cycle is conducted only when the household has enough laundry collected, so that the loading capacity of the washing machine is used, otherwise the houshold waits. Houshold, however, washes the laundry despite the loading capacity restrictions when a certain, waiting time (defined by the houshold) is elapsed. The consequences of all washing cycles during one year are calculated in terms of CO 2 equivalent emissions caused by the energy, water and detergent consumed for reaching a well-defined level of washing performance. This model offers a high range of possibilities to simulate some of the consumer's behavioral patterns and so helps to identify an optimal washing behavior for different sizes of washing machines.