Measuring local-scale canopy-layer air temperatures in the built environment: A flexible method for urban heat studies

To reduce increasing human morbidity and mortality due to urban overheating, urban cooling strategies need to be targeted towards intra-urban hot spots. The application of findings from numerous urban heat studies is limited because methods do not measure air temperature relevant to the human experience with a sufficient level of data granularity. In this work, we developed and tested a unit consisting of a temperature data logger and a custom-made weather shield that is substantially less expensive than published alternatives and can be deployed with high spatial flexibility to measure canopy-layer (near-surface) air temperature relevant to people living in the built environment. Accuracy of results was compared with a more expensive, commercially available scientific instrument as well as official Bureau of Meteorology weather stations in Sydney, Australia. The unit costs around 15% of the price of the tested alternative and only 25% of the least expensive published alternative. Data quality was almost identical to that provided by more expensive scientific instruments and official weather stations. Temporal and spatial coverage and the resulting granularity of air temperature data were very high. The air temperature measurement method reported here can be used in future urban heat studies to determine intra-urban hot spots. Resultant knowledge can be used to target cooling strategies that maximise benefits to the human population, reducing heat-related illnesses and death in overheating cities.