Cities
already house over
50% of the world’s population, and the number is expected to increase to 60%
by 2030. Rapidly growing cities are bringing with them a host of challenges.
One of them is the Urban Heat Island (UHI) Effect.
An UHI
is an urban area or metropolitan area that is significantly warmer than its
surrounding rural areas due to human activities. The temperature difference
usually is larger at night than during the day.
In
general, cities consume a large amount of energy, have less vegetation to
provide shade and cooling, and are built of materials that absorb and store
heat.
The
UHI effect occurs due to a combination of factors, including: (1) heat-trapping
buildings and infrastructure, (2) reduced vegetation, (3) urban geometry, and
(4) increased anthropogenic heat from human activities including traffic, industrial activities, lighting,
air-conditioning (AC) etc.
It
is a global problem affecting cities around the world, particularly in the
tropics. The increased temperature reduces thermal comfort, discourages people
from walking or cycling, and increases the energy used for air conditioning. It
impacts comfort, liveability, as well as the economy.
According
to a study by Verisk
Maplecroft, heat stress threatens to cut labour productivity in south-east
Asia by up to 25% by 2030, by limiting human ability to undertake activity. UHI
is also responsible for more intense storms, which sometimes lead to
flooding.
Singapore
is also susceptible to the effects of UHI. In tropical Singapore, dense urban structure
causes heat to be trapped while anthropogenic heat caused by human activities
worsens the situation. Studies by Matthias
Roth and Winston T.L. Chow
found that the UHI effect over the urbanised Singapore averages about
4°C, though it can exceed 7°C at certain times of the day.
Many
believe that it is time for Singapore to develop a strategy to combat urban
warming; not only to enhance liveability, but also to reduce carbon emissions
to tackle global climate change.
In
Singapore, a research project called Cooling Singapore was
launched in 2017. Funded by the National Research Foundation of Singapore
(NRF), Cooling Singapore is the first multi-institutional initiative led by the
Singapore-ETH Centre, together with National University of Singapore (NUS), Singapore-MIT
Alliance for Research and Technology (SMART), and TUM CREATE (established by the
Technical University of Munich).
With
the aim of improving outdoor thermal comfort of tropical Singapore, the research
initiative hopes to add to actionable knowledge for policymakers with a roadmap
in tackling the problem of UHI.
At EmTech Asia 2018, OpenGov spoke to Professor
Gerhard Schmitt who is the Lead Principal Investigator of Cooling Singapore. Professor
Schmitt is also a Professor of Information Architecture at ETH Zürich and Director of the Singapore-ETH
Centre.
With
research focus and expertise on responsive, sustainable and liveable future
cities, specifically in the rapidly-urbanising regions across the world,
Professor Schmitt shared with us his insights on how to combat UHI in Singapore
and the role of Cooling Singapore in this effort.
Prof Schmitt urged the city-state to
“take more mitigation measures because the acceleration of temperature increase
is real.” The increase in temperature is a result of both global climate change
and the increase in anthropogenic heat in Singapore.
“The increase of the urban
temperature in Singapore, resulting from a combination of global and local
effects, is accelerating. The key thing is to deal with the sources of heat as
soon as possible. We simply cannot afford to add more heat to our environment,”
Prof Schmitt emphasised.
In his presentation at EmTech Asia, Prof Schmitt presented
the key objectives and multi-stakeholder approach of the Cooling Singapore
project.
(1) Research
With
strong emphasis on science and data, the project aims at mapping the UHI effect
and outdoor thermal comfort in Singapore to identify the areas that are most
affected.
The
team uses a numerical weather prediction model coupled with an urban canopy
model to compare the temperature in Singapore as it exists today with a hypothetical
Singapore without any buildings and with only vegetation and thereby, estimate
the UHI effect. Similar simulations can be performed for all anthropogenic
factors, such as transportation.
Outdoor thermal comfort, as
experienced and perceived by people, is modelled with sensation, perception and
behavioural models incorporated. To understand people’s behaviour, the
researchers conduct measurement campaigns, online surveys and interviews.
(2) Evaluating options
The
team then identifies viable mitigation strategies and evaluates their expected
effectiveness in reducing the UHI effect in the hotspot areas. In the process,
the team also systematically identifies knowledge and technology gaps and will develop
a roadmap to guide future UHI-related research and development (R&D)
activities in Singapore.
A
catalogue of eighty-six different mitigation strategies have been identified
for Singapore across 7 clusters: Shading, Transportation, Energy, Materials and
Surfaces, Urban geometry, Water bodies and Vegetation.
(3) Developing a roadmap
Research
findings will be consolidated into reports to develop a policy roadmap on how
Singapore can tackle UHI. As the roadmap is catered to policymakers and other
stakeholders, a 14-member UHI task force has been set up, comprising stakeholders
from local agencies and universities including Nanyang Technological University
(NTU) and Singapore University of Technology and Design (SUTD).
The
draft Roadmap will be presented during the Cooling Singapore Symposium at the
World Cities Summit on 11 July 2018.
(4) Prototype development
A
prototype, in the form of a web-based tool, will be developed to support the
research and mapping activities. The digital model will also help citizens
identify cooler parts of Singapore.
In
our subsequent discussion, Prof Schmitt explained, “The ultimate objective is to make Singapore a
liveable city in the long run. If we do not act now, together with the
population increase, the problem of urban heat island is only going to worsen.
With a deteriorating environment caused by increasing temperatures, citizens
will be less productive and suffer detrimental health effects.”
When
asked about at what stage is Singapore currently in, in terms of tackling the
UHI effect, Prof Schmitt said the
project represents a first step, but the initiatives are running in parallel.
“The first step is to explore the
gaps as this type of detailed research, such as on the movement of heat in the
urban structure, has never been done before. Mitigation strategies have been
developed and the tool development is underway,” he continued to share.
Acknowledging the fact that both
research and urban climate design to alleviate the UHI effect will take time,
Singapore must take a holistic approach that balances between urban climate
design to change our physical environment and our interaction with it, in
implementing mitigation measures.
On
mitigation, Prof Schmitt suggested that new developments in Singapore should be
designed in a way such that they are cooler than existing ones by increasing
air flow, be it artificial or natural air flow into and around the building.
They should also be powered by renewable energy resources. This will eventually
change the mindset of people, their behaviour, as well as their physical
comfort.
While designing new buildings with more liveable features is possible,
improving existing buildings in built-up areas is a much more daunting task.
This is particularly true in highly urbanised cities in Southeast Asia.
Prof Schmitt suggested a few ways. For example, old buildings can be
refurbished to improve air flow. Technology can be applied to existing
buildings to increase air flow, or even lift the ceiling to increase usable
space.
Technology, including the use of artificial intelligence (AI) and sensors
for data collection, is a key backbone for the project’s research and
development of urban solutions.
At the moment, the Cooling Singapore team is developing an interactive web-based
application tool to help map and visualise the UHI effect. With real-time data
and simulation, the app will provide information on noise, pollution, heat and
humidity.
According to Prof Schmitt, the idea is based on the observation that
people intrinsically like to enjoy the outdoor environment. Noting that rising
temperature has detrimental implications on people’s health, technology can
help to map the most pleasant route, in the form of a smartphone application.
That will help individuals to plan their routes and activities better.
Instead of the currently available static maps, the use of AI can assist
the simulation to show the dynamic movement of the population and their
activities throughout the day. Accurate data also increases the stability and
accuracy in temperature predictions.
The team behind the Cooling Singapore project
believes that the interactive map detailing the outdoor thermal comfort of
Singapore would be important for policy-makers to understand the actual
situation in order to effectively tackle the problem.
According to Prof Schmitt, the map can help policy-makers in better
urban planning, such as in deciding where to locate schools and other community
facilities. It can also be used to predict which are the most visited places, so
authorities can plan accordingly.
In planning the urban landscape of Singapore, Prof Schmitt believed that
there should be more clusters of mixed-use living and working development
across the island and cited the positive example of the recently announced Punggol Digital District (PDD) development plan.
“The latest plan to develop it into Punggol Digital District is exactly
the right thing to do. People learn and work in the same district they live,
avoiding traffic, pollution and time lost in daily commute. Creating more self-contained
communities and ecosystems is how part of Singapore could be developed. The key
is to bring together the places where people live and work to reduce
unnecessary daily commute and travel,” he said.
Prof Schmitt also emphasised that planning ahead is a better way to
improve the environment and its sustainability. However, citizen engagement is
equally important as government-led initiatives.
When asked about how a city can balance between
citizens’ desire for more liveable environment and the city’s development need
due to land scarcity, Prof Schmitt pointed out that there are always natural
limits to a city or country’s development before it becomes unbearable to live.
But even in built-up areas of the city,
we could do more to make it more walkable, liveable, and open up more public
spaces.
Through this project, the team hopes to help planners, stakeholders and
residents visualise a liveable environment through the interactive map and the
easy-to-understand visualisations.
“When people start to see the change in
temperature and how it positively affects their lives, they will change their
mindset, behaviour and support these initiatives to make Singapore an even more
liveable city,” he concluded.
