A building’s virtual 3D model allows us to spot the errors of traditional 2D drawings. The most typical problem is the arrangement of HVAC, electrical and fire protection systems in the tight spaces available. In close collaboration with the designers, we follow up every step of the real construction process at the model level and during the multi-phase clash detection we list the colliding elements and then create a clash-free model. This allows the necessary corrections to be carried out before construction begins, resulting in significant cost and time savings during the implementation.