This paper presents a development work which aims at practical applications of ideas built on experiences in practise and education and the theoretical development in the BAS.CAAD project. The important difference between BAS.CAAD and CAD programs of today is the possibility to handle user organisation, building design and site in the same program. This means that design today has to be done in at least 3 separate programs with different ways of defining objects. It is then a computer technical problem to mix and study the relations between objects of separate origin. In a recent project our method to overcome this difficulty in CAAD computing was using a Multimedia program making visual simulations to analyse consequences of form etc. As the process went on and forms where more concrete it was possible to make simulations worth showing and discussing to involve colleagues, clients and users