ExoBuilding: Physiologically Driven Adaptive Architecture

Our surroundings are becoming infused with sensors measuring a variety of data streams about the environment, people and objects. Such data can be used to make the spaces that we inhabit responsive and interactive. Personal data in its different forms are one important data stream that such spaces are designed to respond to. In turn, one stream of personal data currently attracting high levels of interest in the HCI community is physiological data (e. g., heart rate, electrodermal activity), but this has seen little consideration in building architecture or the design of responsive environments. In this context, we developed a prototype mapping a single occupant's respiration to its size and form, while it also sonifies their heartbeat. The result is a breathing building prototype, formative trials of which suggested that it triggers behavioral and physiological adaptations in inhabitants without giving them instructions and it is perceived as a relaxing experience. In this paper, we present and discuss the results of a controlled study of this prototype, comparing three conditions: the static prototype, regular movement and sonification and a biofeedback condition, where the occupant's physiological data directly drives the prototype and presents this data back to them. The study confirmed that the biofeedback condition does indeed trigger behavioral changes and changes in participants' physiology, resulting in lower respiration rates as well as higher respiration amplitudes, respiration to heart rate coherence and lower frequency heart rate variability. Self-reported state of relaxation is more dependent on inhabitant preferences, their knowledge of physiological data and whether they found space to 'let go'. We conclude with a discussion of ExoBuilding as an immersive but also sharable biofeedback training interface and the wider potential of this approach to making buildings adapt to their inhabitants.