- freely available
Challenges 2015, 6(1), 3-25; https://doi.org/10.3390/challe6010003
2. Literature Review on Urban Heatwave Resilience
2.1. Urban Heatwaves; Causes, Consequences and Measures
2.2. Social Interplay of Heatwaves
2.2.1. Population Related to Suburban and City Centre Urban Heat Islands
2.2.2. The Risk of Vulnerability to Heatwaves
2.2.3. Thermal Perception in Terms of Physical, Physiological and Psychological Factors
- perceived control, such as the unpleasant experience of waiting for someone to arrive,
- past experience, such as the weather in summer time,
- the time of exposure,
- naturalness—natural building materials help with thermal acceptance, environmental stimulation—people coming outside to enjoy the sunshine can bear heat for considerably longer periods than their counterparts, and
2.2.4. Mitigation Techniques to Provide Adaptation Opportunities
2.3. Precinct Retrofitting for Heatwave Resilience
3. Results and Discussion
3.1. Key Aspects to Quantify and Improve Precinct Heatwave Resilience
- Australian cities are low in density and their microclimates are influenced by the sea breeze; therefore the typical UHI pattern peaking in CBDs are not always traceable [70,71]. In addition, Australian cities are highly sprawled; hence the climatic condition differences across the metropolitan regions can be immense. Hence, research on UHWs should not overlook suburban areas and the use of finer-scale location-specific weather data is essential.
- Researchers tend to interpret the UHIs in terms of daily mean temperature. The characteristics of the day-time and the night-time UHIs and therefore UHWs are divergent due to location and magnitude differences across time. Consequently, in UHW resilience studies the function of the precinct should be accounted for and real population size should be used instead of the residential address based population size.
- Neither the findings of socioeconomic vulnerability nor real-world thermal perception have been integrated in the evaluation of retrofitting techniques. However, to increase heatwave resilience the knowledge of the heatwave vulnerability and perception of the local population is crucial.
- UHI literature exists on city, building, public space or canyon-scales. Since the indoor and outdoor environment temperature is closely related, only precinct analysis provides the opportunity to examine the relationship between indoor and outdoor air temperature, considering also the population’s characteristics.
3.2. Implementation of the Key Aspects for Heatwave Resilient Precincts
3.2.1. Quantify Precinct Heatwave Resilience
- excess energy use during UHWs
- excess water use during UHWs
- excess morbidity and mortality during UHWs
- the perception of population of UHWs
- excess traffic to “cool pools” during UHWs, where cool pools are mainly air conditioned community spaces, acclaimed as a cool retreat during heatwaves, such as a local library or swimming pool.
3.2.2. Influential Factors of Rpr
|Mitigation as UHI Indicators||Adaptation as Population Exposure||Population Vulnerability|
|urban albedo/sky view factor (SVF)/frontal area index (FAI)||INDOORS||age above 65 and under 4|
|--||energy performance of the buildings envelope||--|
|green space ratio||air-conditioning coverage||the level of isolation (single household)|
|green intensity ratio||natural ventilation opportunity||pre-existing health conditions|
|water surface ratio||OUTDOORS||qualification|
|permeable surface rate||outdoor shadow coverage||hours spent at home: unemployment rate and people who work at home|
|Materials’ average albedo||cool pool availability||ethnicity- length of residence, born here or offshore|
|population density||POPULATION CHARACTERISTICS||emergency service availability|
|Materials’ thermal storage capacity||outdoor activity and confined spaces||electricity price|
|traffic type (eg.:electric cars), intensity||activity level||--|
|energy-efficient building stock||crime rate (people unlikely to use public space and leave the window open at night)||--|
3.2.3. The Retrofitting Toolkit
|Scope of Responsibility||The Mitigation Technique is Implementable by Individuals or Only by Community, Public Service.|
|Spatial scope of benefit||It is beneficial for a smaller or bigger community.|
|Effect on the time distribution||Depends on the function of the building.|
|Effect on population vulnerability||Private green roofs and any green space can be more effective for affluent populations, who can afford to irrigate more than a less affluent one.|
|Cost||The initial construction and planning costs.|
|Willingness to retrofit and use the implemented opportunities||Investigate the common acceptance of the mitigation techniques.|
|Lifetime||The lifetime of a tree is expected to be much longer than external shading.|
|Maintenance||All additional cost related to the mitigation techniques’ maintenance.|
|“Adaptive increment” (where applicable), increase of neutral thermal zone||The additional temperature beyond the standard based neutral zone which can be bearable by the users due to the implementation of adaptive behaviour and adaptation techniques [ 7]. Solutions with impact on heat perception, such as increased use of natural materials applicable.|
|Savings in annual energy and carbon emission||The findings of building energy modelling will be included.|
|Peak demand||Foster the decrease of peak demand in energy, water, ambulance service.|
|Level of independency from fossil fuels||Reduce the precincts’ dependency on fossil fuels and raise inhabitants’ resilience.|
|Positive impact on psychological perception via information distribution||For instance, inbuilt weather-forecast information spot in office buildings’ foyers.|
Conflicts of Interest
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