The globe is at a crossroads in terms of the urban heat island effect, with rising surface temperatures due to urbanization and an expanding built environment. This cause-and-effect connection may be linked to weather-related dangers, natural disasters, and disease outbreaks. Urbanization and industrialization will not lead to a secure and sustainable future. Finding solutions to problems such as the heat island effect is at the forefront of scientific research and policy development. Sustainable ways to decrease urban heat island impacts are a core principle for urban planners. This literature study examines the benefits of adding green infrastructure and sustainable materials in built-up areas to reduce the urban heat island effect. Materials such as reflective street pavements, coating materials including light-colored paint, phase-change materials, color-changing paint, fluorescence paint, and energy-efficient appliances are considered sustainable materials, whereas green infrastructure like green roofs, green walls, green parking and pavements, and shaded streets are considered to mitigate the urban heat island effect. The hurdles to the widespread adoption of such practices include a lack of governmental legislation, insufficient technological development, an erroneous estimation of economic gains, and unwillingness on the part of impacted parties.

Climate change is one of the biggest challenges of our times, even before the onset of the Coronavirus (COVID-19) pandemic. One of the main contributors to climate change is greenhouse gas (GHG) emissions, which are mostly caused by human activities such as the burning of fossil fuels. As the lockdown due to the pandemic has minimised human activity in major cities, GHG emissions have been reduced. This, in turn, is expected to lead to a reduction in the urban heat island (UHI) effect in the cities. The aim of this paper is to understand the relationship between human activity and the UHI intensity and to provide recommendations towards developing a sustainable approach to minimise the UHI effect and improve urban resilience. In this study, historical records of the monthly mean of daily maximum surface air temperatures collected from official weather stations in Melbourne, New York City, Tokyo, Dublin, and Oslo were used to estimate the UHI intensity in these cities. The results showed that factors such as global climate and geographic features could dominate the overall temperature. However, a direct relationship between COVID-19 lockdown timelines and the UHI intensity was observed, which suggests that a reduction in human activity can diminish the UHI intensity. As lockdowns due to COVID-19 are only temporary events, this study also provides recommendations to urban planners towards long-term measures to mitigate the UHI effect, which can be implemented when human activity returns to normal.

Urban green infrastructures (UGI) have been suggested as a natural solution to tackle the problem of human thermal comfort as well as to reduce energy consumption in buildings under the pressures of rapid urbanization and global warming. However, the acceptance of UGI to mitigate the urban heat effect is not yet universal. The development of such an infrastructure is also not consistent across the regions, emphasizing the different objective parameters and methodologies. A systematic review has been conducted to analyze the published research work on UGI, targeting thermal comfort, in the past decade to identify the trends of UGI development around the world. The result shows that most of the studied locations were situated around the Mediterranean Sea region in a temperate climate, and most of the studied cities are within countries with a high gross domestic product, large urban area and urban population, primary energy consumption, and high greenhouse gas and carbon dioxide emissions. Extensive green roofs are the most popular type of UGI and mostly use Sedum plants. In the published studies, experimental setups are the most common methods by which to collect data. EnergyPlus is the most popular software used to conduct energy analysis for buildings, whereas ENVI-met is more commonly used for microclimate analysis. These results indicated that the direction of UGI studies is driven by climate characteristics and the socioeconomic factors of geographical location, which favor low construction cost and maintenance needs, with a minimal irrigation requirement for small-scale UGI projects. Understanding the trend of UGI approaches for thermal comfort allows researchers to standardize practices that help the decision-making process for future researchers while recognizing the limitations and potential of current UGI practices. It is recommended that future studies should include arid and equatorial climate regions, with more focus on large-scale projects including high-rise building environments to comprehensively evaluate the effectiveness of UGIs.

Driven by rapid urbanisation and global climate change, the increasing frequency and intensity of the Urban Heat Island effect poses significant risks to the health and well-being of urban dwellers across the world. To combat extreme heat and ensure a safe level of thermal comfort for urban residents, innovative and sustainable technologies, such as green infrastructure and cool roof coatings, have been incorporated into building design and urban planning. This study aims to evaluate and compare the effectiveness of six different cool roof coating brands in reducing surface temperatures under the harsh and fast-changing climate conditions in Melbourne, Australia. A pilot-sized experimental cool roof was installed on the rooftop of an existing office building to monitor surface temperature variations using a thermal infrared camera, accompanied by a statistical analysis to evaluate potential surface temperature reductions under varying weather and sky conditions. The results of this study show that the application of cool roof coatings reduced the surface temperature by at least 8.7 °C and up to 34.2 °C, corresponding to reductions of 13.2% and 53.6% from the maximum surface temperature, respectively. When comparing the six cool roof paint brands, it was observed that Brand 4 demonstrated the best performance, reducing the surface temperature to a minimum value of 34.3 °C (45.5% reduction) when the maximum surface temperature was 62.9 °C. On the other hand, Brand 5 showed the least effective performance but still achieved a reduction of 15.8 °C (25.1% reduction). This study highlights the potential of cool roof coatings as an effective urban heat mitigation strategy by lowering building surface temperatures. Alongside other urban heat mitigation strategies, such as green roofs and green walls, cool roof coatings offer a viable solution for buildings.

Under the current energy crisis and climate change, sustainable urban planning and building design are a priority to achieve a net-zero future, as energy use in buildings for thermal comfort is one of the major carbon emission contributors. To adapt to a rapidly growing and stringent urban environment, where buildings are causing more emissions due to more frequent and severe extreme hot weather events, the parametric design approach has great potential and flexibility in providing a sustainable solution by simulating different design scenarios. This study aims to analyse urban geometry and identify the impact of various built environment scenarios on outdoor thermal comfort under certain climates. The Grasshopper program was used along with the Ladybugs plug-in to provide visualised outcomes of outdoor thermal comfort, with simulation models on Rhinoceros 3D Version 7 SR37 (7.37.24107.1500). Comparing the thermal comfort performance of different design scenarios, based on building height, orientation and urban geometry, helps to identify which factors are more impactful on building design. This study demonstrates the workflow of parametric design in analysing the microclimate pattern and outdoor thermal comfort performance of the existing built environment in Melbourne, Australia, to provide an insight for stakeholders and builders to inform better decision-making in urban planning and building design in order to achieve a zero-emission future.

Modern cities are rapidly evolving in terms of urban morphology, driven by exponential population growth that accelerates the urbanisation process. The changes in land use have increased urban area and density, intensifying the urban heat island (UHI) effect, which poses one of the biggest threats to human health and well-being, especially in metropolitan regions. One of the most effective strategies to counter urban heat is the implementation of green infrastructure and the use of suitable building materials that help reduce heat stress. However, access to green spaces and the affordability of efficient building materials are not the same among citizens. This paper aims to identify the socio-economic characteristics of communities in Melbourne, Australia, that contribute to their vulnerability to urban heat under local conditions. This study employs remote sensing and geographical information systems (GIS) to conduct a macro-scale analysis, to investigate the correlation between urban heat patterns and socio-economic characteristics, taking into account factors such as vegetation cover, built-up areas, and land use types. The results from the satellite images and the geospatial data reveal that Deer Park, located in the western suburbs of Melbourne, has the highest land surface temperature (LST) at 32.54 °C, a UHI intensity of 1.84 °C, a normalised difference vegetation index (NDVI) of 0.11, and a normalised difference moisture index (NDMI) of −0.081. The LST and UHI intensity indicate a strong negative correlation with the NDVI (r = −0.42) and NDMI (r = −0.6). In contrast, the NDVI and NDMI have a positive correlation with the index of economic resources (IER) with r values of 0.29 and 0.24, indicating that the areas with better finance resources tend to have better vegetation coverage or plant health with less water stress, leading to lower LST and UHI intensity. This study helps to identify the most critical areas in the Greater Melbourne region that are vulnerable to the risk of urban heat and extreme heat events, providing insights for the local city councils to develop effective mitigation strategies and urban development policies that promote a more sustainable and liveable community.