International Journal of Biometeorology

, Volume 62, Issue 7, pp 1311–1324 | Cite as

Effect of long-term acclimatization on summer thermal comfort in outdoor spaces: a comparative study between Melbourne and Hong Kong

  • Cho Kwong Charlie Lam
  • Kevin Ka-Lun Lau
Original Paper


The Universal Thermal Climate Index (UTCI) is an index for assessing outdoor thermal environment which aims to be applicable universally to different climates. However, the scale of UTCI thermal stress classification can be interpreted depending on the context. Previous studies validated the UTCI in individual cities, but comparative studies between different cities are scarce. This study examines the differences in thermal perception and clothing choices between residents from two climate zones over similar UTCI ranges in summer. We compared summer thermal comfort survey data from Melbourne (n = 2162, January–February 2014) and Hong Kong (n = 414, July–August 2007). We calculated the UTCI from outdoor weather station data and used t tests to compare the differences in thermal sensation and clothing between Hong Kong and Melbourne residents. When the UTCI was between 23.0 and 45.9 °C, Melbourne residents wore significantly more clothing (0.1 clo) than Hong Kong residents. Hong Kong residents reported neutral to warm sensation at a higher UTCI range compared with the dynamic thermal sensation (DTS) model. Moreover, Melbourne residents reported warm and hot sensation at a higher UTCI range than the DTS model. Respondents in Melbourne also exhibited different responses to the mean radiant temperature under shaded and sunny conditions, while such a trend was not observed in Hong Kong. It would be advisable to define different thermal sensation thresholds for the UTCI scale according to different climate zones for better prediction of the outdoor thermal comfort of different urban populations.


Outdoor thermal comfort UTCI Clothing Thermal adaptation Urban microclimate 



The authors acknowledge the CRC for Water Sensitive Cities and the Royal Botanic Garden (RBG) Victoria for their support, as well as the volunteers from the RBG Victoria and Monash University for conducting the surveys in Melbourne. This study is financially supported by the National Key R&D Program of China [2016YFC0202206] and Science and Technology Program of Guangzhou, China (grant No. 201607010066), as well as the National Natural Science Foundation of China (grant No 51478486). This study is also supported by CUHK Direct Grant for Research (Project code 4052157) and General Research Fund, Research Grant Council (Project codes 14603617 and 14643816).


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© ISB 2018

Authors and Affiliations

  1. 1.School of Atmospheric SciencesSun Yat-sen UniversityGuangzhouChina
  2. 2.Guangdong Province Key Laboratory for Climate Change and Natural Disaster StudiesSun Yat-sen UniversityGuangzhouChina
  3. 3.School of Earth, Atmosphere and EnvironmentMonash UniversityClaytonAustralia
  4. 4.CRC for Water Sensitive CitiesMelbourneAustralia
  5. 5.Institute of Future CitiesThe Chinese University of Hong KongShatinHong Kong
  6. 6.CUHK Jockey Club Institute of AgeingThe Chinese University of Hong KongShatinHong Kong
  7. 7.Institute of Environment, Energy and SustainabilityThe Chinese University of Hong KongShatinHong Kong

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