Space as an architectural theme has been explored in many ways over many centuries, designing the architectural space is a major issue in both architectural education and in the design process. Based on these observations, it follows that computer tools should be available that help architects manipulate and explore space and spatial configurations directly and interactively. Therefore, we have created and extended the computer tool Sculptor. This tool enables the architect to design interactively with the computer, directly in real-time and in three dimensions. We developed the concept of'space as an element'and integrated it into Sculptor. These combinations of solid and void elements - positive and negative volumes - enable the architect to use the computer already in an early design stage for conceptual design and spatial studies. Similar to solids modelling but much simpler, more intuitive and in real-time this allows the creation of complex spatial compositions in 3D space. Additionally, several concepts, operations and functions are defined inherently. Windows and doors for example are negative volumes that connect other voids inside positive ones. Based on buildings composed with these spaces we developed agents to calculate sound atmosphere and estimate cost, and creatures to test building for fire escape reasons etc. The paper will look at the way to design with space from both an architect's point of view and a computer scientist's. Techniques, possibilities and consequences of this direct void modelling will be explained. It will elaborate on the principle of human machine interaction brought up by our research and used in Sculptor. It will present the possibility to create VRML models directly for the web and show some of the designs done by students using the tool in our CAAD courses.