Dwellings and systems are becoming ever more complex. In achieving high energy performances, the interaction among user, building and systems plays an increasingly crucial role. We studied this interaction in 16 recently renovated low-energy dwellings, to advance the field in terms of methods, and to derive pointers for improved renovation concepts. We used sensors to monitor the indoor environment. And we further developed a method that uses questionnaires, diaries and a so-called 'walk through the house' interview technique to gain insights into occupant behaviour and the reasons for the occupants' behaviours. The results show that the observed behaviour was almost always a normal response to the situation, but often not the behaviour that was expected when designing the renovation concept. A major reason for this was the occupants' efforts to reduce discomfort, which was often the result of the renovation solution itself (for example draught, noise or a warm bedroom). So, we found that behaviour was often a quite normal reaction to the renovation solution. We conclude that the resulting underperformances of renovation concepts are caused by technology centred design. We posit that this can be improved by testing renovation concepts in real world situations. @en