How Singapore Beats the Heat
For cities, it's not cool to be hot
Today’s read is about ~7-9 minutes long
Hello dear readers,
For those of us living in the Northern Hemisphere, we’ve been going through a pretty hot summer, and not in the fun way. In just the last few months
The UK weather service issued their first ever extreme heat warning in July
Multiple Tokyo Olympic events were rescheduled due to high temperatures
And most of the Western United States got the crap kicked out of it with heat waves, wildfires, and droughts
There’s clear evidence that this summer has been hot, recent summers have been getting hotter, and this trend will likely continue if we don’t something about it.
So why do we care? And what does this all have to do with cities? Well, firstly we care because heat waves cause tens of thousands of deaths/year globally, and in the US are the most deadly form of natural disaster, killing more people than earthquakes, fires, floods, etc. Additionally, a 2018 UN report estimated that by the year 2050, over 2/3 of the world’s population will be living in urban areas.1 This means that how cities address the issue of extreme heat will be incredibly important in mitigating the loss of life and other consequences that stem from it.
Why Singapore?
Today I’ll be looking at how Singapore is working to combat this issue of extreme heat. Now, Singapore certainly isn’t the only city to face this problem, so why am I focusing on them today? A few reasons:
Singapore might not be the hottest city, but it is hot, and with an average temperature difference of only ~3°F (~1.67°C) between their coldest and hottest months, it’s pretty much hot year round (see chart below). Not only that, but it’s average temperature has been rising at ~2x the global average since the 1950s.
Source: Weatherspark In addition to being hot, Singapore is also incredibly humid which, from a scientific standpoint inhibits the body’s ability to cool itself through sweating, and from a personal standpoint, sucks.
Singapore is dense and compact. While legally and politically a nation, the entire country is ~280 sq mi (~725 sq km) large, somewhere between the size of Chicago and New York. This means that Singapore is an excellent, mostly contained “laboratory” for urban experimentation.
Singapore’s political system is… efficient. While technically a parliamentary republic, in practice the current incumbent party has been in power for ~60 years, and wields incredible authority without much real opposition. This, combined with the small geographic size of Singapore means that there’s little difference between national, state/provincial, and city policy. This allows for much less friction in urban development projects, especially in contrast to western cities who are often slowed down by jurisdictional issues, zoning laws, and legal red tape.2
Singapore is wealthy and technologically advanced. Many of the solutions we’ll discuss today are technology-heavy, and the city-state’s wealth, and propensity for spending it, means they are quick to try, fail, and adapt when it comes to new potential solutions.
All these qualities make Singapore an intriguing candidate for analyzing different ways to combat urban heat. For that reason, they’re the focus of today’s update.
The Urban Heat Island effect
Before we get into specific cooling methods, we need to understand one of the main drivers of this issue, the Urban Heat Island (UHI) effect. This is the tendency for cities to both produce, and also retain more heat than surrounding areas, and is well-documented in urban areas around the world. There are several possible reasons for this phenomenon, including but not limited to…
Skyscrapers preventing breezes from forming, attracting heat with their large, dark surfaces (depending on building material) and expelling heat from their high levels of energy usage
Surfaces like asphalt, concrete, and other materials attracting and retaining heat
Cars, buses, and other gas-powered transit systems producing exhaust and heat as a byproduct of use and/or combustion
Heavy A/C usage, both commercial and residential, consuming energy and expelling heat
Building over or destroying natural greenery and bodies of water which may have otherwise acted as heat sinks, provided shade, etc.
In some cases urban areas can be up to 20°F (~11°C) hotter than the areas surrounding them, meaning that combating extreme heat is arguably even more important in cities, where the UHI effect compounds the already globally rising temperatures from climate change.
District Cooling: aka air conditioner? I hardly know her!
Probably the first thing that comes to mind when we think about “cooling off” is air conditioning. The problem with that is, while useful on an individual level, conventional A/C usage can actually exacerbate heat issues on a citywide level. This is because your A/C unit’s electricity usage, as well as the heat expelled out of the back of the unit, strongly contribute to the overall effect in the city. This problem is especially apparent in Singapore, which has the highest A/C installation per capita in SE Asia, and where A/C usage is the 2nd leading cause of CO2 emissions.
Singapore’s answer to this was to construct one of the largest and more impressive alternative cooling systems in the world, Marina Bay’s district cooling network. District cooling is distinct from conventional A/C systems, and works in three main stages:
Cold water is pumped via underground pipes from a central cooling plant to buildings in the surrounding area.
This water circulates throughout the buildings, absorbing heat and cooling down their interiors.
The now heated water is then piped back to the central cooling plant, chilled at an industrial scale, and then pumped back out to the same buildings, repeating the cycle over again.
By aggregating cooling demand for multiple city blocks, and chilling water at a central location with more modern and industrial methods, district cooling systems benefit from economies of scale and can consume 60-80% less energy than the average A/C system, and 20-30% less energy than even the most advanced, conventional cooling systems.
Is district cooling worth the price?
One barrier to utilizing district cooling is that it does require large upfront costs (~$82M USD for this Marina Bay system) to build the necessary infrastructure. This means that it might not always be a practical solution, especially in cities that have older infrastructure than Singapore (which is… a lot of cities). This upfront cost is slightly offset by the lower operational costs (more efficient cooling) and also by the decreased costs of subsequent developments, as you no longer need to install separate cooling units or towers for each building. This also saves space, which can then be used for additional residential/industrial developments as well.
It’s hard to calculate the breakeven point for district cooling systems, as it depends on both the number of buildings using the system, as well as the rate at which they are built and added into the district cooling network, but one estimate for the Marina Bay development from Australia’s National Cleantech Conference and Exhibition estimates that it provides around ~42% more long-term cost savings over traditional A/C systems.
While promising, it should also be noted that district cooling is not yet widespread throughout Singapore, and due to land constraints and the relatively mild potential for alternative energy production in Singapore, ideal district cooling coverage might only be closer to 30% of the city. As with all potential initiatives, cities need to evaluate on a case by case basis if the upfront costs and realities of their geography justify adoption of district cooling systems.
Mobility and Transportation
The second area in which Singapore is reducing their heat output is transportation and mobility, which accounts for 14% of all emissions in Singapore. There are two main ways they go about this:
Method 1: Electrifying vehicles and using alternative energy sources
In researching this newsletter I was surprised to learn that most gas combustion engines are actually pretty inefficient at moving vehicles, with just ~20% of the produced energy going to moving the vehicle, and the other 80% lost as heat or exhaust out of the tailpipe. While Singapore is taking positive steps like buying more electric buses, as of October 2020 out of a fleet of 5,800 buses they had just 25 electric ones, so thus far, converting to more efficient vehicles isn’t much of a tenable strategy on its own.
Method 2: Reduce the total number of vehicles overall
Another more immediate way to reduce heat output from transportation is directly reducing the total amount of cars in the city. This not only reduces emissions because there are fewer cars on the road, but also because by removing cars from the road, congestion tends to decrease, cars move faster, and thus spend less time idling in traffic.
"The amount of heat generated by a vehicle is directly proportional to the amount of consumed fuel, which is, in the urban case, roughly inversely proportional to the average speed of the vehicles. Therefore, all measures that reduce congestion… can be considered mitigation measures for reducing heat flux coming from vehicles." - “Strategies for Cooling Singapore” (2017)
This is basically saying that, as your car sits idling in traffic, you’re not only wasting gas, you’re producing heat. I love the way that transit journalist John Surico phrases it, calling cars idling in traffic "…essentially 300-horsepower gas-powered personal air conditioners.” Therefore, any efforts towards reducing total cars on the road will also help reduce total heat output.3
You can drive but it’s gonna cost you
To this end, Singapore has several methods to reducing car ownership/total cars on the road:
Fast, reliable, (literally) cool public transit: I’ve said it before and I’ll say it again, if you want people to drive less, you need to provide alternatives for them. Singapore has an extensive MRT metro system and a decent public bus system, with mostly air-conditioned and/or well-shaded stops that make travel more comfortable for residents.
Certificate of Entitlement: In order to own a car in Singapore, you need to buy a Certificate of Entitlement (COE). This is a 10-year “permission to drive” agreement that individuals must purchase from the city, and in some cases they can be more expensive than the actual car itself, costing upwards of $60K SGP (~$45K USD). Additionally, every 10 years you need to purchase a new COE, further de-incentivizing car ownership.
Working to combat heat output from vehicles by making them more efficient, or just reducing their total number is a promising step towards combating the UHI effect, but for it to work cities need to provide residents with sufficient mobility alternatives in the form of good public transit, walkable streets, bike lanes, etc. Generally speaking I believe these steps are pretty much always a good decision in cities, and so when it comes to keeping Singapore cool that is still very much true as well.
Singapore’s “Garden City” initiative
The final way that Singapore cools things down is through the extensive use of urban greenery. Strategic placement of trees within cities have been shown to cool down neighborhoods by up 3.6°F (~2°C), both because of the natural shading/carbon absorption effects of trees, and also because this in turn can lead to less A/C usage, which we already know further exacerbates the UHI effect.
This is immediately obvious just walking through the streets of Singapore.
Much of the greenery can be dated back to the 1967 Garden City initiative started by then Prime Minister Lee Kuan Yew. The original stated goal was to transform Singapore into "A garden city beautiful with flowers and trees, and as tidy and litterless as can be" (source). While it has changed scope over the past few decades, overall it’s widely been hailed as a success, winning Singapore plenty of international acclaim in areas like sustainable design, eco-friendly policies, and quality of life measurements.
And Singapore has no intention of resting of their leafy-green laurels, with plans to plant an additional million trees by 2030. While urban greenery on its own is probably not enough to combat the UHI effect, in conjunction with the other methods discussed today it certainly does help, in addition to providing residents with greater personal comfort, quality of life, and beautifying the city.
Additional Methods
These three main features, district cooling, reducing vehicular emissions, and urban greenery are all impressive, but they only scratch the surface of all of Singapore’s cooling efforts. Other tactics like the use of smart surfaces and alternative building materials, strategic skyscraper placement to encourage breezes and increase ventilation, and extensive investment in private mobility, smart building, and other anti-UHI effect companies are all additional methods that Singapore continues to explore.4
For my money, one of the most interesting innovations is Singapore’s Digital Urban Climate Twin (DUCT). DUCT is a real-life simulation of the city, incorporating features like buildings, traffic flows, vegetation, etc. combined with projections on surface heat absorption rates, vehicle and A/C unit emissions, industrial energy consumption, etc. All this information is collected and modeled in a digital environment, allowing city planners, policymakers, and architects to accurately predict and evaluate the heat/climate impacts of planned developments or initiatives before they are actually completed. This provides valuable insight, saves time and money, and is fun to say. For a more detailed breakdown of the DUCT, I highly recommend Fabien Clavier’s “Cities in Mind” podcast episode on it which can be found here.
Conclusion
Today we focused on three main methods that Singapore is undertaking:
Globally, A/C accounts for ~20% of all electricity usage, so alternative methods like Singapore’s district cooling system represent a massive step towards more sustainable heat reduction efforts.
Vehicular emissions can be reduced by introducing more sustainable energy technologies, or by outright discouraging car ownership/driving altogether. However, inhibiting driving must be accompanied by parallel investment and support of public transit and other transportation alternatives. These measures would go a long way in reducing pollution, congestion, and heat output from transportation.
Planting trees and emphasizing urban greenery might not have as significant of an anti-heat effect as the first two methods, but does heavily contribute to quality of life and city beautification efforts.
Not all of Singapore’s heat reduction solutions are applicable in every city, but many of their efforts can and should be replicated as much as possible.
That’s it for today, this update was a slightly different format than usual, so please do let me know what you thought in the comments below, and don’t forget to absolutely PULVERIZE that like button.
Stay “cool”
-Max
To be fair, this is also basically why I think EVERY article I write about urban issues is important, but that’s besides the point.
I think there are some legitimate criticisms to be made about politics in Singapore, which I will cover in a future update on how different municipal government styles impact urban innovation and design. For today’s purposes though, from a pure planning/development standpoint they are incredibly efficient, making them a prime candidate to analyze a city’s cooling efforts.
There are many other benefits of reducing traffic and getting some amount of cars off the road (economic, safety, quality of life, environmental, etc.) which I’ve covered in previous newsletters, but since today’s topic is urban heat, I’ll just focus on that today.
In 2017 they released a list of 80+ different measures, both planned and already enacted, which you can read here. I may explore some of these other methods in a future update as well, so if you just love alternative construction materials stay tuned.
Loved this one!