ExoBuilding explores the novel design space that emerges when an individual's physiological data and the fabric of building architecture are directly linked. In its current form ExoBuilding is a tent-like structure that externalises a person's physiological data in an immersive and visceral way. This is achieved by mapping abdominal breathing to its shape and size, displaying heart beat through sound and light effects and mapping electro dermal activity to a projection on the tent fabric. The research is positioned in relation to previous work and the iterative development of ExoBuilding from to-scale to full-size prototype is described. An informal pilot study suggests a biofeedback loop between inhabitants and ExoBuilding, which results in some cases in a relaxing experience. Overall, ExoBuilding raises pertinent questions about the use of personal data in the built environment. In a future where it is technologically possible for personal data to be made available to our technologically infused environments, how do we give inhabitants the necessary understanding, tools and controls to manage their engagement?