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BANGKOK: Prasert Saisamphan’s house used to be a windy space, surrounded by trees. Now the 65-year-old is struggling to breathe, surrounded by confined concrete and the dust of a growing city.
“When I was in my 20s, there were still no condos built here. The weather was nice and cool. We only use a fan at night. Nobody had air conditioning in my house, ”he said.
“Now there is less air. It feels like I can’t take a deep breath. “
The view from Prasert’s house on Klong Khlang in central Bangkok is dominated by tall highway pylons and, in the distance, seemingly ever-growing residential towers.
“It’s hot this year. It is so hot that electrical charges increase significantly. It’s so hot that I installed water sprinklers on the ceiling. It’s so hot I need water spray. It feels twice as hot compared to last year, ”said Jurairat Kruephimai, another local resident.
Prasert Saisamphan relies on the shade of a tree near her house to keep her cool. (Photo: Jack Board)
The heat they feel cannot be imagined. The effect of a phenomenon known as an urban heat island (UHI) is rampant in Bangkok, causing maximum temperatures to rise above surrounding areas. It is particularly felt at night.
Roads, buildings and other urban concrete infrastructure absorb solar radiation during the day and release it slowly at night, causing a rise in temperature. Vehicles add to the problem, as does the cleaning of green spaces to make way for new construction.
Dr. Sigit Dwiananto Arifwidodo from Kasetsart University has studied UHI extensively in the Thai capital. In 2012, one of his studies found that the maximum temperature difference between urban and rural areas was 7 degrees Celsius. And until 2018, he noted that UHI-amplified temperatures continued to rise year after year.
“Higher temperatures due to the urban heat island effect are increasing every year. At first, we were surprised, ”Dr. Arifwidodo told CNA.
“When we map it out, the area that is a hotspot gets bigger and bigger. The last one where we used the 2018 data, it’s pretty much all of Bangkok. “
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The concrete of large buildings such as condominiums contributes to the urban heat island. (Photo: Jack Board)
HIGH URBAN DENSITY
Bangkok is not the only one to grapple with the UHI problem: it is increasing in regularity and magnitude in Asian cities, as urban areas expand, green areas shrink, and poor ventilation suffocates dense spaces.
While hot temperatures during the day pose risks to workers exposed to prolonged periods outdoors, research shows that the most damage can be done at night, in the form of heat stroke or exhaustion.
A recent study by the Chinese University of Hong Kong (CUHK) highlights the dangers of consecutive nights of rising temperatures as a result of climate change and the urban heat island effect.
In July, Hong Kong experienced a heat wave that triggered a “very hot warning” for 20 consecutive days. High nighttime temperatures, especially when combined with hot days, were found to significantly intensify health impacts.
“The night is supposed to give the body a chance to recover and rest from the heat of the day, but ‘hot nights’ make recovery and rest less effective,” said Dr. Kevin Lau, research assistant professor. of the Institute of the Future Cities in CUHK.
“Due to the congested living environment with poor ventilation, the occupants of the subdivided floors are particularly vulnerable and cannot recover from the heat of the day,” he said.
The impacts affect more particularly women, the elderly and the very young. As the city’s population ages and living areas become more populated, the risks of heat stress are expected to worsen.
Green spaces have been dramatically lost in large Asian cities as urban sprawl grows. (Photo: Jack Board)
“Urban density needs us to build up and pack more people in a finite space. When you do that, you get the problems of warmer temperatures at night, mainly from the urban heat island, ”said Winston Chow, associate professor of Science, Technology and Society at Singapore University of Management.
“If you have a higher proportion of older people living in cities exposed to warmer conditions during the day and at night, you will have health problems.”
Some of the solutions Hong Kong researchers are offering for their city include better urban planning and building design, taking into account increasing rates of green space, natural air flow, and the changing challenges of climate change.
Adjunct Professor Chow said those strategies can be applied to Singapore, which has also seen UHI temperature increases of 7 degrees Celsius, despite different weather conditions and urban layout. Hotspots have been detected in areas such as Punggol, Sengkang, Seletar, and Woodlands.
Adapting existing infrastructure, such as modernizing apartment buildings or adding rooftop gardens, can only provide micro improvements to local temperatures. “The problem is for new buildings, that’s where a lot of the new climate-conscious design ideas can be applied,” he said.
That dilemma exists in the Thai capital, where thermal mass expansion will be “almost impossible” to reduce, simply by creating more green spaces, Dr. Arifwidodo explained. The city government’s new master plans include heat conscious initiatives, but are voluntary and complicated by zoning laws.
Vulnerability to urban heat of the districts of Singapore from 14:00 to 16:00 (Source: Cooling Singapore)
“If there are concrete buildings and no green spaces, there is not much we can do. But each building has its own age: after five or 10 years it will need renovation, and the new regulations may include adding greenery to the building, ”he told CNA.
The dense industrialized provinces around Bangkok are already experiencing UHI effects, just as bad, if not worse, than the city proper, but there are still mitigation options if governments coordinate their efforts, according to Dr. Arifwidodo.
Similarly, Adjunct Professor Chow emphasized that throughout Southeast Asia, it is secondary cities far from capitals where consideration and forward thinking must now be applied, to avoid the same problems.
“The fastest growing cities are secondary cities, like Chiang Mai, Surabaya, Danang. Those are places where you will get the heat island and the overheating problem if we follow the same mistakes that we have made in urban development in the past, ”he said.
“New cities in terms of development, have to be built by people who work outdoors in hotter environments. They will have much more exposure to heat stress, not only during the day but also at night when they return to their migrant worker dormitories or confined spaces, without the benefit of a cool space to recover. “
Heat is trapped by thermal mass during the day and released at night. (Photo: Jack Board)
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“IT’S GOING TO BE HOT”
In Bangkok, Dr. Arifwidodo says the problem goes unnoticed due to a lack of mortality or morbidity caused directly by heat stress, especially compared to other parts of the country.
“At the city level, there has been very limited attention, especially from the provincial government because they think, from a health perspective, the number of people who die from heat stroke is relatively low,” he said.
“There are some heat-related illnesses in Bangkok, but this mainly occurs in people with a low socioeconomic status, such as construction officials, motorcycle drivers and other jobs that require whole days outdoors.”
Experts agree that the UHI, and climate change in general, will only serve to increase the levels of inequality in the region. Today, air conditioning protects millions of residents from dangerous nighttime heat, but for those who can’t afford it, the future will be harder to cope with.
“It’s going to be hot. Imagine that night temperatures rise from 25 degrees Celsius to 27 degrees Celsius at night, imagine how much you will need to depend on air conditioning. Think of all those in low-income countries, it will be much worse for them.” said Adjunct Professor Chow.
Air conditioning has its own damaging environmental footprint, especially when the energy needed to power it is generated by dirty power sources. Far from solving the problem of urban heat, it only changes, from indoors to outdoors.
The night is meant to provide the body with a chance to cool off. (Photo: Jack Board)
“The air conditioning is like you’re getting fat, but instead of going on a diet, buy bigger pants,” said Dr. Arifwidodo.
“When we use air conditioners, we create heat outside and help increase temperatures in the microclimates of the surrounding areas. Higher use will result in higher energy consumption and increase inequalities between communities, ”he said.
For many of the residents of Klong Khlang and other poorer communities, air conditioning is an unimaginable luxury.
Trees, herbs and vegetables line the walkways and adorn the roofs of their modest homes, little attempts to cool their surroundings, especially during the summer months of March through May.
“Although I have trees around my house, it is not that useful. Concrete absorbs heat. People trust the fans, ”said Jurairat.
But this year, it is hot. Even the fan is not useful. I can not stand it “.
