Abstract: Contemporary spaces for surgery are highly energy intensive, with much of this energy driving powerful air conditioning systems intended to force pre-cooled air down onto the patient, surgical staff and instruments to keep airborne pathogens from sedimenting on the patient and equipment during surgery and to drive them up and out through high level exhausts. The carbon footprint from these systems is prodigious in a service required to dramatically cut emissions. Sufficient doubts have arisen from experimental modelling and data collected in such surgical theatres that pathogens are expelled efficiently to encourage broader speculation about the fundamental configuration of spaces for surgery. One prospective avenue is the investigation of the aseptic movement’s operating room designs of the late nineteenth and early twentieth centuries before the adoption of air conditioning. Historical review and testing of theatre design, as part of the Excising Infections in Surgical Environments (ExISE) project, identified a particularly carefully designed and innovative operating room in Hamburg’s general hospital of 1897. The St. Georg’s Operationshaus (1899) is reconstructed digitally, analysed theoretically and modelled experimentally to determine modern utility as a green theatre. Results are promising but are affected fundamentally by the parallel intent to introduce prodigious natural daylighting; however, the effects of this on the air flow patterns in the space could be managed by modern materials and control technologies.