The aspect of sound as a design element in an architectural context has been discussed for a long time, but there are still today very few permanent projects put into practice. The functional use of acoustics is easily comprehended when utilized to reduce unwanted noise from roads, or when it is perfected to convey speech and music in concert halls. To add sounds to create a sense of space, use it as a quality or defining identity is however still an unexplored field of knowledge. Finding the right balance between creating a quality for the space with dynamics and variety, while still being sustainable over time is challenging. The paper presents theories, methods, findings and results from a large project including nine installations. The project concerns indoor sound installations in large public spaces in Stockholm including acoustic investigations, electro acoustic installations and composition of sound installations for the specific space. The method is both scientific and art-based. The sound design is used as a way of empowering site-specific functions and architectural themes, but also in some cases as a solitary intentional characteristic quality of the space.