Ventilation operation in hospital isolation room: A multi-criterion assessment considering organizational behaviour

Guidelines for isolation rooms in hospitals require keeping these rooms at negative pressure differential, but the guidelines do not impose a particular ventilation strategy how to achieve this. In principle, one could use variable ventilation regimes responding to interventions that cause a potential contamination risk such as the opening of doors. The variable ventilation regime would temporarily increase the volume offset and hence induce a higher negative pressure differential, whereas during other times the negative pressure differential would be kept at an acceptable minimum. In practice, however, VAV boxes (i.e. damper) are often set to deliver constant air volume. In this paper an adaptive VAV operation is introduced in response to the complaint that current operation is not adequate as it leads to excessive fan energy consumption. The paper evaluates the current practice while demonstrating efficiencies of the adaptive VAV operation, and supporting a rational selection of ventilation operation through a set of objective performance criteria. The chosen criteria relate to potential exposure of contamination, energy consumption and thermal comfort. It is shown that the two operation modes do not make a noticeable difference in the potential spread of contaminant and thermal comfort. However, the adaptive VAV mode consumes significantly less energy. It is also inspected whether the transition between low and high pressure differential is fast enough to reduce the temporary contamination exposure. To guarantee a safe transition, nurses may have to wait until the pressure control system gets settled. Hence, an additional performance aspect concerning the potential of delayed direct care is added on to the multi-criteria decision-making framework. A Bayesian decision theory is applied to compare two options given the stakeholders’ environment. This reinforces the finding that the ultimate decision should be based on the multi-criteria comparison of building operational and organizational outcomes.