Cities are confronted with more frequent heatwaves of increasing intensity discouraging people from using urban open spaces that are part of their daily lives. Climate proofing cities is an incremental process that should begin where it is needed using the most cost-efficient solutions to mitigate heat stress. However, for this to be achieved the factors that influence the thermal comfort of users, such as the layout of local spaces, their function and the way people use them needs to be identified first. There is currently little evidence available on the effectiveness of heat stress interventions in different types of urban space.The Cool Towns Heat Stress Measurement Protocol provides basic guidance to enable a full Thermal Comfort Assessment (TCA) to be conducted at street-level. Those involved in implementing climate adaptation strategies in urban areas, such as in redevelopments will find practical support to identify places where heat stress may be an issue and suggestions for effective mitigation measures. For others, such as project developers, and spatial designers such as landscape architects and urban planners it provides practical instructions on how to evaluate and provide evidence-based justification for the selection of different cooling interventions for example trees, water features, and shade sails, for climate proofing urban areas.
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Built environments are increasingly vulnerable to the impacts of climate change. Most European towns and cities have developed horizontally over time but are currently in the process of further densification. High-rise developments are being built within city boundaries at an unprecedented rate to accommodate a growing urban population. This densification contributes to the Urban Heat Island phenomenon and can increase the frequency and duration of extreme heat events locally. These new build-up areas, in common with historic city centres, consist mainly of solid surfaces often lacking open green urban spaces.The Intervention Catalogue is the third publication in a series produced by the Cool Towns project and has been designed as a resource for decision makers, urban planners, landscape architects, environmental consultants, elected members and anyone else considering how to mitigate heat stress and increase thermal comfort in urban areas. Technical information on the effectiveness of the full array of intervention types from trees to water features, shading sails to green walls, has been assessed for their heat stress mitigation properties, expressed in Physiological Equivalent Temperature (PET). The results shown in factsheets will help the process of making an informed, evidence based, choice so that the most appropriate intervention for the specific spatial situation can be identified.
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With increase in awareness of the risks posed by climate change and increasingly severe weather events, attention has turned to the need for urgent action. While strategies to respond to flooding and drought are well-established, the effects - and effective response - to heat waves is much less understood. As heat waves become more frequent, longer-lasting and more intense, the Cool Towns project provides cities and municipalities with the knowledge and tools to become heat resilient. The first step to developing effective heat adaptation strategies is identifying which areas in the city experience the most heat stress and who are the residents most affected. This enables decision-makers to prioritise heat adaptation measures and develop a city-wide strategy.The Urban Heat Atlas is the result of four years of research. It contains a collection of heat related maps covering more than 40,000 hectares of urban areas in ten municipalities in England, Belgium, The Netherlands, and France. The maps demonstrate how to conduct a Thermal Comfort Assessment (TCA) systematically to identify heat vulnerabilities and cooling capacity in cities to enable decision-makers to set priorities for action. The comparative analyses of the collated maps also provide a first overview of the current heat resilience state of cities in North-Western Europe.
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Urban planning will benefit from tools that can assess the vulnerabilityto thermal stress in urban dense cities. Detailed quick-scan heat stressmaps, as made in this study for Johannesburg, have proven valuable inthe decision-making process on this topic. It raised awareness on theurgent need to implement measures to tackle the effects of climatechange and urbanization. Awareness on heat stress has led to theimplementation of measures to mitigate the effects of climate change.As in other countries, nature-based solutions (e.g. green roofs and walls,swales, rain gardens, planting trees etc) are considered in urban areasin South Africa for various reasons. The awareness of the effect ofnature based solutions on heat stress is still low, which can be improvedby the use of heat stress maps. Some of these measures are alreadymapped on the open source web tool, Climate-scan(www.climatescan.nl) for international knowledge exchange aroundthe globe.
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The liveability of cities worldwide is under threat by the predicted increase in intensity and frequency of heatwaves and the absence of a clear spatial overview of where action to address this. Heat stress impairs vital urban functions (Böcker and Thorsson 2014), hits the local economy (Evers et al. 2020), and brings risks for citizens’ health (Ebi et al. 2021). The ongoing densification of cities may escalate the negative consequences of heat, while rising climate adaptation ambitions require new pathways to (re)design public places for a warmer climate. Currently, policy makers and urban planners rely on remote sensing and modelling to identify potential heat stress locations, but thermal comfort models alone fail to consider socio-environmental vulnerabilities and are often not applicable in different countries (Elnabawi and Hamza 2020).In the Cool Towns Interreg project, researchers collaborated with municipalities and regions to model urban heat stress in nine North-Western European cities, to find vulnerabilities and to measure on the ground (see Spanjar et al. 2020 for methodology) the thermal comfort of residents and the effectiveness of implemented nature-based solutions. Using the Physiological Equivalent Temperature (PET) index, several meteorological scenarios were developed to show the urban areas under threat. The PET maps are complemented by heat vulnerability maps showing key social and environmental indicators. Coupled with local urban planning agendas, the maps allowed partner cities to prioritize neighbourhoods for further investigation. To this end, community amenities and slow traffic routes were mapped on top of the PET maps to identify potential focus areas.A comparative analysis of the collated maps indicates certain spatial typologies, where vital urban activities are often influenced by heat stress, such as shopping areas, mobility hubs, principal bicycle and pedestrian routes. This project has resulted in the development of a multi-level Thermal Comfort Assessment (TCA), highlighting locations where vulnerable user groups are exposed to high temperatures. Standardized for European cities, it is a powerful tool for policy makers and urban planners to strategically identify heat stress risks and prioritize locations for adapting to a changing climate using the appropriate nature-based solutions.
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While the optimal mean annual temperature for people and nations is said to be between 13 °C and 18 °C, many people live productive lives in regions or countries that commonly exceed this temperature range. One such country is Australia. We carried out an Australia-wide online survey using a structured questionnaire to investigate what temperature people in Australia prefer, both in terms of the local climate and within their homes. More than half of the 1665 respondents (58%) lived in their preferred climatic zone with 60% of respondents preferring a warm climate. Those living in Australia's cool climate zones least preferred that climate. A large majority (83%) were able to reach a comfortable temperature at home with 85% using air-conditioning for cooling. The preferred temperature setting for the air-conditioning devices was 21.7 °C (SD: 2.6 °C). Higher temperature set-points were associated with age, heat tolerance and location. The frequency of air-conditioning use did not depend on the location but rather on a range of other socio-economic factors including having children in the household, the building type, heat stress and heat tolerance. We discuss the role of heat acclimatisation and impacts of increasing air-conditioning use on energy consumption.
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There is a clear demand for a collaborative knowledge-sharing on climate adaptation and mitigation. The aim of most climate adaptation platforms is (inter)national knowledge exchange and raising awareness about climate adaptation in urban areas and promote solutions such as Nature-based solutions (NBS) and floating infrastructure. However their multiple benefits are often unknown to the wider public. During seminars (February 2020) in Indonesia climate adaptation measures where mapped and the relevance of the climate adaption platforms such as ClimateScan was evaluated by the means of workshops and a survey. The platform ClimateScan holds now over 5000 locations in 5 main categories of climate adaptation (water, nature, agriculture, energy and people). The conclusions from the workshops in Semarang and Surabaya show high relevance scores for NBS: permeable pavement and swales; for infiltration of stormwater to groundwater; for mitigation of high temperatures with heat stress measures; and flood barriers to mitigate flooding. There were low scores for floating urbanization because this is not a culturally accepted practice in contradiction to other parts of the world. Indonesian floating infrastructure as a floating library, restaurant and airport terminal where mapped during workshops bringing the total of international floating structure locations to 150. The workshops have raised awareness among participants and contributed to capacity building by empowering the participants to map and review climate adaptation measures. A high majority see the value of climate adaptation platforms and will use it in the future.
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Stormwater flooding and thermal stresses of citizens are two important phenomena for most of the dense urban area. Due to the climate change, these two phenomena will occur more frequently and cause serious problems. Therefore, the sectors for public health and disaster management should be able to assess the vulnerability to stormwater flooding and thermal stress. To achieve this goal, two cities in different climate regions and with different urban context have been selected as the pilot areas, i.eY., Tainan, Taiwan and Groningen, Netherlands. Stormwater flooding and thermal stress maps will be produced for both cities for further comparison. The flooding map indicates vulnerable low lying areas, where the thermal stress map indicates high Physiological Equivalent Temperature (PET) values (thermal comfort) in open areas without shading. The combined map indicates the problem areas of flooding and thermal stress and can be used by urban planners and other stakeholders to improve the living environment.
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Urban flooding and thermal stress have become key issues formany cities around the world. With the continuing effects of climatechange, these two issues will become more acute and will add to theserious problems already experienced in dense urban areas. Therefore, thesectors of public health and disaster management are in the need of toolsthat can assess the vulnerability to floods and thermal stress. The presentpaper deals with the combination of innovative tools to address thischallenge. Three cities in different climatic regions with various urbancontexts have been selected as the pilot areas to demonstrate these tools.These cities are Tainan (Taiwan), Ayutthaya (Thailand) and Groningen(Netherlands). For these cities, flood maps and heat stress maps weredeveloped and used for the comparison analysis. The flood maps producedindicate vulnerable low-lying areas, whereas thermal stress maps indicateopen, unshaded areas where high Physiological Equivalent Temperature(PET) values (thermal comfort) can be expected. The work to dateindicates the potential of combining two different kinds of maps to identifyand analyse the problem areas. These maps could be further improved andused by urban planners and other stakeholders to assess the resilience andwell-being of cities. The work presented shows that the combined analysisof such maps also has a strong potential to be used for the analysis of otherchallenges in urban dense areas such as air and water pollution, immobilityand noise disturbance.
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We summarize what we assess as the past year's most important findings within climate change research: limits to adaptation, vulnerability hotspots, new threats coming from the climate–health nexus, climate (im)mobility and security, sustainable practices for land use and finance, losses and damages, inclusive societal climate decisions and ways to overcome structural barriers to accelerate mitigation and limit global warming to below 2°C.
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