Commentary: Singaporeans’ reliance on air-cons will only lead to more discomfort

SINGAPORE: The heat in Singapore is back with a vengeance - again. Year in, year out, we complain about how hot the weather is, then speed-walk to the nearest shaded area or air-conditioned location to get some relief.

The heat is not going anywhere. In fact, it’s only going to get worse. Last year was Singapore’s fourth-warmest year on record, and researchers are projecting even hotter temperatures in the months and years to come.

By the end of the century, Singapore could face up to 351 “very hot” days a year, where temperatures exceed 35 degrees Celsius. Days with peak temperatures of 40 degrees Celsius may appear as early as 2045, Minister for Sustainability and the Environment Grace Fu told parliament in 2022.

Concerns are growing over the potential threat to health as Singapore gets warmer. A recent study by the National University of Singapore found that aside from affecting worker productivity and cognitive capacity, heat stress can cause lower fertility - bad news for our already record low fertility rate.

SINGAPORE’S LOVE FOR AIR-CON

Singapore is a mere 137km north of the Equator, meaning there's no escaping the relentless heat and humidity that position it among the top countries worldwide for air-conditioning use.

Singapore's founding father, Mr Lee Kuan Yew, considered air-conditioning one of the greatest inventions, saying it “changed the nature of civilisation by making development possible in the tropic”. “Without air-conditioning, you can work only in the cool early-morning hours or at dusk,” he was quoted as saying.

Singaporeans have grown accustomed to relying on air-conditioning to combat the heat.

It’s impossible to imagine the modern-day office or shopping mall without air-con; 99 per cent of private residences are equipped with air-conditioners, as are the majority of public housing units.

This love of air-con has led to a significant rise in household electricity consumption - 17 per cent in one decade, according to a National Environment Agency survey in 2017. Air-conditioning alone accounts for about 24 per cent of an average household’s electricity consumption.

Collectively, buildings and residences make up the second-largest source of carbon emissions in Singapore at 19 per cent, a sizeable portion of which is from air-conditioning, following the industrial sector's 60 per cent.

This spotlights an urgent need for dialogue on energy efficiency and sustainability. It's critical to reconsider our reliance on air-conditioning and explore sustainable alternatives that align with Singapore's environmental goals.

HOW DO AIR-CONS CONTRIBUTE TO THE CLIMATE CRISIS?

Air-conditioners, fundamentally, do not create cold or heat; they merely move heat from indoor to outdoor.

For instance, upon returning home and switching on the air-conditioner, it compresses and releases refrigerant, absorbing heat indoors and expelling it outdoors, thus momentarily relocating human discomfort.

When the air-conditioner is turned off and the windows are opened, the indoor coolness dissipates outside, and the initial hot air returns from outdoors.

When discussing the primary culprits of global warming - such as gas-burning power plants, gasoline-powered vehicles and methane-emitting livestock - air-conditioning seems less conspicuous. Yet, these cooling devices are potent accelerators of climate change.

Many air-conditioners use hydrofluorocarbons, which are potent greenhouse gases, as refrigerants, in addition to consuming vast amounts of electricity generated from fossil fuels.

As the world warms, more people turn to air-conditioning for relief, further heating the planet in a vicious cycle. The World Economic Forum estimates that unchecked, air-conditioning-related greenhouse gas emissions could increase global temperatures by 0.5 degrees Celsius by the century's end.

Cooling is responsible for more than 7 per cent of global emissions and is expected to double by 2030 and triple by 2050, according to the United Nations Environment Program.

Although Singapore's compact size makes its emissions relatively minor compared to countries like Japan and the US, the impact is still significant and as a responsible nation, we must take care of our part.

What can Singapore and Singaporeans do in this space? Do we need a rethink of how to cool the city?

BREAKING THE CYCLE

Air-conditioners exacerbate the urban heat island effect by transferring indoor heat outdoors, intensifying the heat experienced on our island and in cities worldwide.

This effect is magnified through several channels: Heat emission from air-conditioner condenser units, especially in densely populated urban areas; energy consumption, primarily from burning fossil fuels; and waste heat released during operation.

Moreover, the widespread use of air-conditioners has led to buildings that rely less on natural ventilation and passive cooling strategies, trapping more heat in urban environments and amplifying the heat island effect.

While quantifying the exact contribution of air-conditioning heat emissions to the heat island effect is challenging, a study by global sustainable development consultancy Arup shows that significant "hot spots" in the Singapore Central Business District are up to 6 degrees Celsius hotter than their rural surroundings.

It's crucial to foster a mindset where air-conditioning is not the only go-to solution for extreme temperatures. Sustainable passive cooling strategies, such as abundant greenery, shading devices, water features, and clever ventilation, could be prioritised.

Innovative ideas like tracking time spent in air-conditioned spaces and associating this data with personal carbon footprints and heat contributions to the outdoors are technically feasible with today's technology and widespread use of smart and wearable devices.

This could help individuals monitor their impact on carbon emissions and the heat island effect.

WARMING UP TO INNOVATIVE COOLING TECHNOLOGY

For office and commercial buildings, the BCA Green Mark scheme encourages designs and operations that reduce air-conditioned areas, and also sets a global standard for centralised air-conditioning systems.

Some buildings in Singapore have also started using alternative cooling technology like hybrid cooling, which uses fans in air-conditioned spaces with slightly elevated room temperatures, such as 27 degrees Celsius, potentially saving 10 to 20 per cent of energy. This includes the BCA Zero Energy Building Plus in Braddell.

Real estate developers might consider pre-installing fans in office spaces and residential units to support this initiative.

Locally, there are also many other pioneer projects that have adopted innovative cooling technologies.

In Singapore's push for sustainability, innovative cooling technologies are making a significant impact in the management of building temperatures. The SMU Connexion Building, PSA Maintenance Base Admin Building at Tuas port and Gaia at Nanyang Technological University utilise passive displacement cooling to efficiently manage indoor climates. This system uses chilled coils and natural convection to cool a room, eliminating the need for mechanical fans. As a result, it reduces energy consumption and leads to considerable electricity cost savings for operators.

In another example, DBS Newton Green, a 30-year-old four-storey office building, has been retrofitted with hybrid solar air-conditioners.

In a hotter world, access to cooling equipment is not just a luxury, it is also a necessity, saving tens of thousands of lives globally each year.

By adopting sustainable cooling strategies and rethinking our reliance on air-conditioning, we can mitigate our contributions to rising temperatures and the urban heat island effect, paving the way for a cooler, more sustainable future.

Dr Ziwen Liu is Lecturer at School of Science and Technology at Singapore University of Social Sciences, Singapore. Dr Guang Yu Jin is Senior Manager at Building and Construction Authority, and Xiangjing Zhang is Operation Manager at BLEMS Pte Ltd.

The views expressed in this commentary are the authors’ personal opinions and do not necessarily represent the official position of any organisation.