Limits of thermal adaptation in cities: outdoor heat-activity dynamics in Sydney, Melbourne and Adelaide

ABSTRACT

Outdoor thermal discomfort discourages outdoor living at the cost of increased demand for indoor air-conditioning. The resulted waste heat from air-conditioning makes a feedback loop with increased outdoor heat stress. Local and seasonal climate expectations, comfort perceptions, demographic specifications, activity choices and socio-cultural norms can affect the adaptation of public life to outdoor heat stress. This paper explores limits of outdoor thermal adaptation in Sydney, Melbourne and Adelaide. Outdoor activity observation and microclimate measurement were conducted in 10 selected public spaces between February 2013 and March 2014. Results indicate that before the outdoor thermal environment of UTCI = 22–34°C, there is no significant decline in outdoor living and people adapted their outdoor activities, clothing and activity rate to achieve thermal comfort. Beyond this neutral thermal threshold, outdoor thermal adaptation shifted towards dismissal of optional and social activities and modification of necessary activities. Space configurations, local climate expectations and flexible activity choices may extend outdoor thermal adaptation by the critical zero-activity thresholds of 48°C. Thereafter, outdoor activity prevention can become the dominant thermal adaptation strategy. Localized limits of outdoor thermal adaptation are to be addressed to facilitate more liveable and healthy cities in the context of climate change.

KEYWORDS:

• Outdoor thermal comfort
• thermal adaptation
• thermal neutrality
• urban microclimates
• public space

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This paper is a part of a national research project on Urban Microclimates of Australian Cities (RP 2005), supported by the CRC for Low Carbon Living with a range of industry and government partners including the City of Sydney, the City of Melbourne and the City of Adelaide. Human activity observation methods are approved by Human Research Ethics Committee at the University of South Australia in 2013 (PR 31464).