Occupant comfort in naturally ventilated and mixed-mode spaces within air-conditioned offices

Contemporary concerns for improving environmental performance in buildings have led to an increased interest in natural ventilation either on its own (NV) or in combination with air-conditioning (mixed mode – MM) as an alternative to traditional HVAC systems. HVAC systems are widely used because they avoid many of the problems encountered with NV or MM – noise, dust, insects, odours, temperature extremes – and readily conform to steady state conditions of thermal comfort. However it is possible that NV or MM can provide improved indoor air quality precisely through variations associated with external climate conditions. This paper introduces an ARC funded project evaluating comfort conditions in MM spaces, using field studies from two buildings. The first, a University campus building in Sydney, offers MM perimeter offices with air-conditioned central spaces, while the second, a commercial building in Melbourne, offers a series of MM spaces that can be used by workers from adjacent air-conditioned office spaces. The aim of the project is to evaluate the feasibility of using MM either in place of or in association with traditional HVAC systems. The outcomes of the project will be used to elaborate the justifications for inclusion of NV spaces and/or NV periods within contemporary office environments. This paper presents preliminary results of the field work at each location.