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Home » Case study: How Singapore is implementing mixed techniques to keep the city cool

Case study: How Singapore is implementing mixed techniques to keep the city cool

Building design and technology use are becoming increasingly important in Singapore’s mission to bring temperatures down. Average data indicates that the city uses double the average annual air conditioning of Australia, and more than four times that of the UK.

Singapore is more focused than most places on finding ways to keep cool and this is understandable as the Southeast Asian financial centre has been heating up twice as fast as the world average over the past six decades, according to government data.

Adding to the factors is that it’s a city just north of the equator, where daily temperatures already average around 27°C year-round.

For decades, foliage has been a key tool in the city’s fight to keep temperatures down. But increasingly, building design and smart technology are central to the strategy: from petal-shaped, ventilating rooftops and cooling, underground water pipes to data modelling designed to help predict how future urban planning decisions will affect heat levels.

Part of the city’s battle is to reduce the temperatures experienced by its 5.7 million residents without drastically increasing its carbon footprint. Even as it strives to halve emissions by 2050, Singapore has more air-conditioning units per capita than anywhere else in Southeast Asia.

“As Singapore is hot and humid, air conditioning becomes very pervasive but it’s also an energy guzzler,” said Wong Nyuk Hien, a professor at the National University of Singapore school of design and environment. “Thus building design should be done to minimise the use of air conditioning. This will also reduce the waste heat dumped to the environment.”

Singapore’s climate-change problems are compounded by the Urban Heat Island effect. Thanks to hard, heat-absorbing surfaces, the temperature of a built-up urban area can be several degrees higher than the land around it. That variance has grown to 7°C from 4.5°C in 2004, according to research by Wong’s team and the Cooling Singapore project at the Singapore-ETH Centre (SEC), a research partnership between the city-state and Switzerland.

The city’s commercial area can generate up to five times more human-generated heat than a residential area, said Dan Richards, principal investigator of the Natural Capital Singapore project at the SEC. While growing levels of traffic and industrial activity boost the amount of heat being released, tall buildings and narrow streets prevent it from escaping.

Singapore — also known as the Garden City — has long recognised the benefits of greenery. Vegetation can reduce air temperature by 1 to 2 degrees Celsius as well as providing shade, Richards noted. Back in 1967, founding Prime Minister Lee Kuan Yew ordered that the island’s streets and roads be lined with shady Angsana and rain trees. Earlier this year, the government announced that it plans on planting one million trees over the next decade, double to the current pace. Coverage now stands about 56%, Wong said. 

But there are limitations too. Having more trees can reduce wind speed and increase humidity. And the cooling effects of plants on building facades are only felt within a four-meter range, with little or no impact at greater distances, according to local studies.

“Whether or not these impacts of vegetation are ‘effective’ depends on the target that planners choose to set, but it also depends on whether alternative technologies and techniques can do better, or provide more cost-effective solutions,” Richards said.

Vegetation “cannot entirely compensate for the active and passive anthropogenic heat that is released into the urban system,” said Gerhard Schmitt, lead principal investigator of the Cooling Singapore project, which explores ways to reduce heat and creates tools and recommendations to help inform policy.

In September, the centre announced it was producing a data model of the city. This “digital urban climate twin” — Duct for short — is designed to allow planners and policy makers to test the temperature impact of different scenarios. Duct will incorporate information on buildings, traffic, vegetation, land surfaces and movement of people, as well as factors such as wind and sunlight.

Singapore can potentially export Duct to other cities facing a similar challenge, Schmitt said.

“We can invent scenarios. We can design scenarios, test them before we actually build them. And if they test very well and we are sure that they will function, then we can start to build them and put them into reality,” he added. “Singapore will be using this new tool to figure out which actions it should take next.”

Smart technologies can also improve temperature control. Over at upcoming new residential area Tengah, a district cooling network will be installed for the first time on the rooftops of public-housing blocks. Based on a commercial system in Singapore’s Marina Bay Financial District, chilled water is piped through the buildings to cool the air. The system’s operator, SP Group, says the network can reduce energy use by 30%, an emissions saving equivalent to taking 4 500 gasoline-powered cars off the road.

It’s clear all these tools, and more, will be needed to mitigate the effects of climate change on the city. Planting trees “cannot hurt and it is also conducive to the quality of life,” said Vinod Thomas, visiting professor at the Lee Kuan Yew School of Public Policy in Singapore.

“But it is not enough by itself by to reverse the warming of the city.”