Knowledge workers share two basic needs: their productivity requires isolation (internalization of knowledge) and interaction (externalization of knowledge), supported by different spatial concepts. None of the work environments involved in the study adequately support all of the phases in the knowledge development process adequately. Collective productivity is primarily determined by the physical dimension of the workplace; whereas the social dimension is crucial for personal productivity. Social interaction has a stronger effect than distraction; and the layout has a stronger effect than comfort.