The urban heat island effect bears a significant impact on human beings, structures, transportation operation and infrastructure, energy needs, the economy and the survival and sustenance of trees and animals.
Large cities are adding to climate change by way of the urban heat island effect (UHIE).
Alleviating heat stress and adapting to a warmer climate entails systemic contemplation. What is needed is a workable network of solutions for dealing with UHIE, including:
The acceptance of scientific facts. Science reveals without question the effects of increased hotness and dryness.
Resilience and survival. We must learn to survive as the climate changes, making sure that extreme weather does not cause mass deaths and disruption.
In order to do this, we must explore the way that human systems interact with ecosystems, and how to manage both. Stockholm Resilience Centre (2014) has developed seven principles to govern the application of resilience thinking: 1) the maintenance of diversity and redundancy, 2) the managing of connectivity, 3) the managing of slow variables and feedback, 4) the fostering of complicated adaptive systems 5) the encouragement of education 6) the increase of public participation, and 7) the promotion of polycentric governance systems.
UHIE impacts boast spatial, geographical and temporal dimensions. Inner city residents will face heat stress at night, when the dense built structure radiates heat, while those residing in outer suburbs will feel it during daylight hours.
In order to curtail urban heat stress, one also should consider nature-borne solutions (NBS) and broaden green (vegetation) and blue (water) infrastructure in cities, which also enhances biodiversity. Yet green and blue infrastructure rarely get attention unless linked with other benefits. NBS supplies co-benefits for dealing with society’s challenges like climate change adaptation, while promoting the health of the ecology. NBS is the practice of working with nature and is inherent to a good number of Indigenous practices.
Many Australian councils have devised “urban greening” strategies. They specify the barriers facing the implementation of UHIE solutions, as emphasised in a recent report by the Environment and Communications References Committee (2018) to the Senate.
Standing among the most major barriers is the area government’s lack of resources for the implementation of urban forest strategies, along with a lack of needed planning mechanisms like revegetation requirements on fresh developments or private land, provisions for the protection of living vegetation, and management of the green/blue infrastructure.
The integration of biodiversity in the context of cooling strategies is another substantial issue. If the co-benefits of infrastructure – like the lowering of heating/cooling bills or water basin management – are not comprehendible to the masses, then no incentive exists to grow vegetation on private developments.
Another major barrier in addressing UHIE is the transformation in the grey infrastructure (for instance, buildings and roads). The building material used – kind, colour, reflectivity, etc. – bears an effect on heat accumulation in communities. Materials selected for strength, aesthetic value or cost-efficient value may worsen heat and fail to supply indoor thermal comfort. Consider, for example, concrete and glass building facades, which heat the outside environment and are very inefficient for the maintenance of indoor thermal comfort.
A balance is needed between economy, constructability, building performance and the future adaptability of our communities. Yet UHIE is not mentioned as a component in building design on the Australian Building Codes Board.
Boasting an urban area of more than 9990km2, Melbourne is 80 percent urbanised, providing homes to 4.9 million people. Melbourne is expected to pass Sydney as Australia’s largest city by the year 2066. Greater Melbourne is expected to expand to 11.2 million people by 2056, with 9 million individuals residing in Melbourne. To support a quickly expanding population, Melbourne’s built environment and natural environment will continue to morph at a rapid rate. Even on a 30-degree Celsius Melbourne day, the CBD is 0.8 degrees Celsius warmer than in non-CBD areas.
In terms of building design, Melbourne is renowned for bluestone paths, dark glass and concrete facades. Confronting the issue of UHIE while maintaining Melbourne’s classic look is a complicated challenge.
In responding to the challenges associated with UHIE, the Victorian government has specified the value of green and blue infrastructure. They have created the Cooling and Greening Melbourne (2017-2020) initiative, with the Victorian Department of Environment, Land, Water and Planning collaborating with RMIT University, CSIRO, and the Clean Air and Urban Landscapes (CAUL) Hub to map and review vegetation, land use, and urban heat in Melbourne, resulting in the creation of interactive spatial maps.
South Australia is making advances to stop UHIE. The January-February 2009 heatwave accompanied the Black Saturday bushfires in Victoria, which killed 173 people. And the heatwave is thought to have caused an additional 374 deaths in Victoria and 32 deaths in South Australia.
In response, the South Australian Southern Region Local Government Implementation Plan 2015-2019 has devised the South Australia Urban Heat Mapping initiative. This serves as a monitoring platform that calls upon thermal imagery to measure land surface temperatures of urban areas and reveal hot spots.
The South Australian state government also recommended amendments to their 30-year Adelaide Development Plan in 2017, which calls upon green infrastructure to reduce building energy usage and enhance biodiversity. Initiatives include the adoption of green roofs, vertical gardens and water-inclusive design in high density and mixed-use building projects to facilitate urban cooling. At Adelaide Airport, water reserved for irrigation and toilet flushing now originate from a wastewater treatment plant, and a stormwater harvesting scheme has been implemented to serve future airport developments.
To use another example, Singapore is almost 100 per cent urbanised, with a population of more than 5.6 million burgeoning at a rate of 1.2 per cent (Dept of Statistics Singapore, 2019), all living in a region that is about 720 square km – a bit smaller in metropolitan area than Canberra, which is about 814 square km.
By the year 2030, Singapore is expected to boast a population of 6.9 million people, thus necessitating Singapore to grow to 760 sq km (Cheam, 2013, Ministry of Trade & Industry, 2013).
Singapore summers boast temps considerably higher in the central business district as opposed to surrounding districts (Chow & Roth 2006, Cooling Singapore 2018). Therefore, the expected population growth is sure to increase UHIE on the island.
Singapore has reduced its dependency on carbon since the ratification of the Paris Climate Agreement in 2016. The island has switched from carbon fuel oil to natural gas and other power sources, and investment in efficient and affordable public transportation options.
The government-subsidised ‘Cooling Singapore’ project involves the collaboration of government agencies with local and international researchers to devise strategies to reduce UHIE and enhance outdoor thermal comfort. Their objective is to supply a “whole of nation” approach that accommodates Singapore’s tropical climate.
In doing so, Cooling Singapore is working with area councils and agencies that coordinate buildings, land use, parkland and waterways, and transport and energy infrastructure to coordinate the drivers of UHIE in each “Local Climate Zone“.
Each district profile supplies info regarding material types, colour and coverage; urban shading patterns; transportation mobility patterns; blue-green-grey ratios and distribution; urban geometry of block and district building landscapes and energy usage profiles.
The Housing Development Board has used the Integrated Environmental Modeller (IEM) for planning the layout of Tengeh Town, Singapore. IEM can facilitate simulations for all of Singapore to examine the subject of microclimate at city scale. (A* Star Singapore, 2020)
Especially in regards to the building sector, the Urban Redevelopment Authority’s LUSH (Landscaping for Urban spaces and High-rises) program was launched in 2009 (URA 2017) to enhance skyrise greenery. Currently, parks, nature reserves and reservoirs take up 13 per cent of land usage (URA 2013 as cited by Zhou & Zhao 2016).
In order to enhance the quotient of green and blue infrastructure on the island, the Building Control Authority has required the growing of greenery on roofs and on upper levels of buildings or on walls. Building designers and developers are now devising cooling designs, which facilitate biodiversity.
The widespread growth of urban greenery at multiple levels is creating a prettier, more sustainable city. This growth doubles as a temperature regulator, supporting community urban farms and supplying health and well-being benefits to people who live there.
Singapore’s success shows that we all must work together to take the heat off–make the world a better, more liveable place.