This paper describes a method for insight generation for sustainable innovations. The method takes a practice oriented approach aiming for product ideas for practice level innovations. The method was applied in a case study on the practice of bathing. Insights on sustainable bathing innovations were gathered during a two-week period in which sixteen participants were asked to create and execute their own experiment for less resource intensive ways of bathing at home. In a group session these insights were translated into product ideas. It was concluded that it is indeed possible to generate product ideas with a practice oriented approach. The experiments in the home context helped the participants to come up with practice level bathing innovations. As predicted, they turned out to have potential to yield strong reductions in resource consumption and compete with the currently dominant practice of daily showering.