As researchers and practitioners from the field of urban development and related disciplines working in the Sustainable Smart Cities research cluster at HTW Berlin, we argue that the concepts of smart and sustainable cities cannot be viewed independently of one another. The systematic linking of both approaches holds great potential. To exploit this, the following seven principles must be observed:

1. Find interfaces and create demarcations
2. Observe principles of sufficiency, efficiency and consistency
3. Highlight conflicts and discuss questions of justice; promote participation and involvement
4. Promote legitimacy and accountability,
5. Create freedom and ensure flexibility,
6. Take technical and social innovations into account and
7. Recognise the relevance of Open Source and diversity in digitisation