Earlier in 2023, Arup launched UHeat, a tool that identifies areas of towns and cities that are experiencing the urban heat island (UHI) effect.

It’s a growing problem in many cities, with profound health impacts, particularly for older, more vulnerable members of the population and those who work outdoors.

Assessing where the issue is being caused, and by what, is where UHeat has particular value. UHeat takes advantage of the power of machine learning to analyse huge volumes of satellite imagery (you can learn more about our related Terrain tool, here). It then tags the materials and other causes that are pushing up the temperature, those combinations of glass, steel, tarmac, vehicles, air conditioning units, data centres and other urban development that are raising average temperatures, compounding the effects of climate change.

For city authorities and commercial developers, UHeat is a valuable tool, offering new insights to those tackling a problem that damages lives and cities’ future viability at the same time. It enables those in power to understand where the problem is, what the causes are, and to model or simulate the most effective mitigations.

But at a greater scale UHeat points to the need for a far more radical vision of urban development, one where nature has fully returned to the cities we live in, where urban greenery and waterways are a central part of what a city ‘is’, not just a peripheral element around which we have built.

Learning from Singapore

The densely populated city state of Singapore shows what is possible. This tropical garden city has long understood the need for natural temperature control and has been pioneering what we now call ‘biophilic design’, where nature is both teacher and solution.

It’s a country that has long known that it’s running out of space. It faces constraints on its natural and forested land. Its tropical climate and humidity are exacerbated by climate change. And with over 8,000 people per square kilometre, the city faces predictably intense UHI problems.

Using UHeat, our latest urban heat snapshot captures what they’ve achieved and where problems persist. We use the tool to analyse the entire city in detail, identifying a large cluster within the Singapore Central Business District (CBD) – including not only high-rise areas but also historical low-rise streets – as the most extreme “hot spots” in Singapore, experiencing temperatures 6°C higher than their rural surroundings. When compared to the city’s coolest spot in the Upper Pierce Reservoir, this cluster is 6.5°C hotter.

Outside the CBD, neighbourhoods experiencing temperatures of at least 5°C above rural surroundings include Orchard, Little India, Marine Parade, Kampong Ubi and Sembawang. The cool zones are mostly located in areas with forests or reservoirs. This includes the central catchment area, the vegetated area located in Lim Chu Kang, Sungei Buloh Wetland Reserve as well as the region located at Khatib Bongsu.

The implication is clear: our cities need to incorporate greenery, water and other natural features if the overheating is to stop.

The fact that areas near water bodies and greenery are cooler spots is evidence that nature-based solutions are incredibly effective at both taming temperature rise and providing an environment-led vision for attractive and enjoyable places to live. It’s a development ethos where natural cycles of vegetation are core to a place’s identity, where green areas and canal systems connect communities and natural absorption of rainwater reduces flood risks. 

Of course, to achieve this level of impact requires thoughtful and detailed planning. 

Greening the city

To tackle the intensifying UHI effect, Singapore has developed the Singapore Green Plan 2030 which encompasses targets of increasing vegetation and new parks, ensuring every household is located within a 10-minute walk from a park. Additionally researchers are developing a Cooling Singapore 2.0 project culminating in the Digital Urban Climate Twin (DUCT) for Singapore, which integrates relevant computational models and region and micro-scale climate models.

At a more conceptual level, many designers are now turning to biomimetic design – where solutions incorporate characteristics, qualities and systems from nature itself. Some years ago, Arup contributed environmental engineering on the canopies at Clarke Quay, a popular area for tourists. The canopy known as the ‘angels’, embodies this biomimetic ethos, comprising umbrella-like structures that provide solar shading and rain protection. It was also intended to protect pedestrians from increasing heat. The frames also support large 'whale tail’ slow speed fans that provide a low level artificial breeze in the streets. It also demonstrates that solving experiential challenges can lead to creative and popular designs that really add to a city’s appeal.

More recently, Yishun, a former industrial district has been exploring how to reimagine itself as a residential area, where buildings were transformed rather than demolished, and where nature takes prominence within the scheme. Our work on this proposal includes a network of greenways, to ensure that the area stays cool and liveable once residents move in. It’s an example of environment-led design thinking.

Digital: enabling sustainability at scale

As a digital tool, UHeat enables smarter long-term thinking, enabling city planners to consider the future with greater confidence. It reminds us that a greener, natural future depends on advanced data-driven tools and insights.

We chose Singapore as another demonstration of UHeat’s value because, somewhat uniquely, the country has a 50-year vision for its future development. Its administration has shown a willingness to look at the predictions, then learn from and respond to them. Climate change challenges us all, wherever we are, to think on these grander timelines. UHeat, among other digital solutions, can play a vital role in helping us to scale up the mitigations that our towns and cities urgently need.

Cooling the region

Tools like UHeat can help authorities understand the impacts, bring forward better policy and planning guidance, and be used by developers to sympathetically future-proof new developments to the growing challenges of our all-too-predictable future climate. The power of this tool lies in its ability to map out the existing status of a city's urban heat issue and empower better decision making. The tool has clear relevance and value for other cities in the Southeast Asia region, many of which are dealing with similar levels of UHI effect as Singapore.