A mechanical approach to design treats buildings as assemblies of components: a structure, a mechanical system, an electrical system, a plumbing system. Each component is optimized for its function, and the components are connected at interfaces. This approach is familiar, teachable, and produces predictable results. It is also deeply limiting, because it cannot capture the synergies that arise when systems work together as a whole. A systems approach to design treats the building as a node in a larger web of flows: energy flows, water flows, nutrient flows, information flows. Components are not optimized in isolation but in relation to each other and to the surrounding environment. The design goal is not maximum performance of each part but optimal performance of the whole, over time. In practice, this means understanding how a decision about building orientation affects heating loads, which affects the sizing of thermal mass, which affects the amount…