Building simulations rely on fixed assumptions and mathematical models to describe a specific building scenario, overlooking the building occupants’ component. Almost 40% of in-home energy use is due occupants interacts with the building systems. The goal of this paper is to understand the magnitude of the performance gap when applied to two case studies in a Mediterranean climate. A set of scenarios are simulated assuming both a typical building usage and possible variations given by the users’ interactions with shading, ventilation and cooling systems. Results show that the magnitude of the effects with a negative impact is bigger if compared to actions that might have a positive influence, this means that simulated results with standard usage assumptions are not an average of the possible effects but they reflect an optimistic outcome given by the optimal equipment usage
