Cooling exposure in hot humid climates: are occupants "addicted"?

According to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), it is clear that the buildings sector presents the biggest potential for deep and fast CO₂ emission reductions on a cost-effective basis. Interestingly, this assessment was premised exclusively on technical (engineering) measures, but ignored completely the behavioural and lifestyle dimensions of energy consumption in the buildings sector. Behavioural change in buildings, however, can deliver even faster and zero-cost improvements in energy efficiency and greenhouse gas (ghg) emission reductions. With this in mind, designers are beginning to shift their attention to how they can widen the range of opportunities available in a building to provide comfort for the occupants, both in new-build and retrofit contexts. This in turn has re-awakened an interest in the role of natural ventilation in the provision of comfort. This discussion about adaptive comfort raises several questions, including the following: How can we shift occupants' comfort expectations away from the static indoor climates of the past towards the more variable thermal regimes found in naturally ventilated buildings? Are building occupants ‘addicted’ to static environments, i.e. air-conditioning (AC)? If so, how tolerant or compliant will they be when the thermally constant conditions provided by AC are replaced by the thermally variable conditions that characterize naturally ventilated spaces? Does the frequency of prior exposure to AC bias building occupants' thermal expectations and, if so, what are the implications of this bias for their acceptance of naturally ventilated indoor climates? Does prior exposure to AC lead building occupants to actually prefer AC over natural ventilation? This article addresses these questions in the context of a large field study of building occupants in a hot and humid climate zone in Brazil (Maceio). The temperature preferences registered on 975 questionnaires in naturally ventilated buildings are statistically analysed in relation to occupants' prior exposure to AC in their workplaces.