Sustainable practice emerges from a carefully crafted choreography between different elements within the built environment. In our design, we program the relationship between both the active and passive elements of the architecture as an interactive system where each component works with each other in a continuous, dynamic feedback loop. The building is designed to be able to decide what would be the most sustainable course of action given the variations in environmental conditions or user needs. It can dynamically customize its behavior by taking into account both real-time conditions, long-term goals and user preferences to re-optimize building performance while maximizing user expectations. http:// mobile.mit.edu/fbk