Whilst airflows through swinging and sliding doors are well understood, the study of airflows arising from the use of revolving doors has so far largely been neglected. This study presents the findings of the first systematic investigation of airflows driven by revolving doors, with particular focus on the fundamental physical processes by which these flows occur. Results from a comprehensive experimental programme reveal that two distinct flow regimes are possible through any given revolving door. The regime achieved depends on whether airflows are either restricted by the time taken by air to flow out of the door, or by the time taken by the door to move air from one environment to the other. The implications of these results for both the energy efficiency and ventilation strategies of buildings accessed via revolving doors are discussed and a systematic method for estimating the volume of air transferred, or the energy loss occasioned, by a given revolving door operating under given conditions is proposed.