Heat Exposure Index


This module is currently a pre release version and only available for Melbourne

To identify the population exposed with the highest exposure to extreme heat the heat exposure index is assess at Statistical Area 1 (SA1) level. The HEI is based on the heat vulnerability index (HVI) by Sun et al., (2019) which combines 3 measurements

  • the exposure to heat which is categorises the LST into 5 quantiles across a region. The 1st quantile indicates the lowest heat exposure and the 5th the highest (top 20%).

  • the sensitivity of the population towards heat stress based on the elderly, very young, persons needing care and population density

  • and the populations adaptive capacity to respond to heat based in their socio-economic status

The HVI assessment requires detailed socio-demographic data, however these data are usually not available for future projects

This module therefore employs a simplified HVI assessment based on the heat exposure of the population at SA1 level. As proposed by Sun et al., (2019), we assess the Heat Exposure Indicator (HEI).

The HEI identifies the urban heat island hotspots in an urban region based on the LST and is used to identify the population with a higher exposure to extreme heat. This means that population living within the areas of the largest exposure will be exposed to higher local air temperatures (see Sun et al., (2019)) during extreme heat conditions and will therefore be exposed to more frequent temperatures above the heat threshold.

The HEI is defined by the quantiles of the normalised average LST temperature at SA1 level. The averages for this case studies range from 30.79 – 58.9 ºC. The 1st quantile (bottom 20%), or HEI 1, have the lowest heat exposure and the 5th quantile (top 20%), or HEI 5, the highest heat exposure. For each HEI the number of effected people within each zone code is assessed. The HEI values are normalised and the results can be compared to similar studies such as Sun et al., (2019). As discussed in the limitation section however, the simplified LST assessment conducted for this module does not take into account regional temperature variations. The temperature thresholds have been defined for the 2018 Base Case and are applied to all scenarios.


Sun, C., Hurley, J., Amati, M., Arundel, J., Saunders, A., Boruff, B., Caccetta, P., 2019. Urban Vegetation, Urban Heat Islands and Heat Vulnerability Assessment in Melbourne, 2018.