Outdoor thermal comfort - An adaptive model to assess thermal comfort in urban outdoors in New Zealand.

This research attempts to integrate human thermal adaptation into thermal comfort assessment in order to explore the complex link between microclimate, thermal comfort, thermal adaptation, and user expectations in outdoor urban parks in New Zealand. The study extends the exploratory analysis and the model developed by D.Walton, V. Dravitzky and M. Donn in 2007. It is based on extensive surveys of over 1000 people in urban parks in Wellington – a temperate but windy climate - and Christchurch – a less windy temperate climate with significantly higher and lower outdoor temperatures than Wellington.

This study has extended the methodology to define a comprehensive human adaption scale (Combined Adaptive Factor) that combines a number of inputs related to thermal responses. The wind, sun, temperature and humidity were measured simultaneously with the survey implementation. The combined adaptive factor comprises a correlation of thermal sensations, behavioural changes and preferences to probe ‘the degree people have to adapt’ to be comfortable in different outdoor conditions. The exploration process to identify how the climate influences comfort resulted in a Thermal Adaptation Index, a linear model represented by temperature, wind, relative humidity, and solar radiation to predict comfort based on climate.

The thermal environment in outdoor urban spaces substantially influences the use of the space as it directly affects peoples’ thermal perception. Improving thermal comfort in the urban outdoor environment can enhance the use of space and ultimately lead to a sustainable social life in cities. The result is improvement in the city inhabitants’ health and wellbeing. Improving the livability and vitality of the urban outdoors also has environmental and economic benefits. It is essential to understand people’s thermal expectations based on their requirements to enhance livability and improve thermal comfort in urban pockets by changing the physical context. Understanding people’s knowledge of the thermal environment and how they accept the thermal effects based on their expectations and functionality can lead to better thermal perception predictions enabling designers to design the physical context for better thermal comfort.

Recent outdoor thermal comfort research has moved to investigate the combined effects of sun, wind and temperature integrating human adaptation aspects. Many field experiments have reported discrepancies with physiological models and have inclined to calibrate these models based on human thermal responses.