Assessment of thermal comfort in transitional spaces

Abstract

Transitional spaces refer to those spaces located in-between interior and exterior environments acting as both buffer spaces and physical links, such as entrance canopies, foyers, lift lobbies, corridors, stairwells, etc. As transitional spaces may constitute a significant portion of the building volume and have large implications to occupants’ experience and building energy consumption, many research studies have come up in recent years to examine their conditions and characteristics. This research aims to investigate the thermal conditions and subjective thermal perceptions of occupants in the different types of transitional spaces. Semi-opened and fully enclosed lift lobbies and corridors in The University of Hong Kong (HKU) campus were chosen for the field study. Theoretical study, survey questionnaires and simple energy simulation have been implemented to examine the thermal comfort requirements, people’s perceptions and energy impact of transitional spaces. It was found that an opened area is easily influenced by variable weather conditions as it is close to natural environment while an enclosed one is totally separated from the exterior environment and commonly air-conditioned. This may lead to different subjective thermal responses in these two types of spaces. It was also discovered that people can accept wider thermal environment in transitional spaces and their thermal response varies with dressing, activity level, past thermal experience and prior thermal preference. It is believed that the current comfort standards and criteria are not designed for transitional spaces. The proposed thermal comfort ranges for transitional spaces were examined in this study using modified adaptive comfort model. This could be used to consider possible changes to the current design guidelines and standards. If the transitional spaces are designed with appropriate energy saving strategies such as passive design, hybrid ventilation and flexible HVAC controls, it can help achieve more energy efficient and healthy buildings in the future.