Oct 14, 2005
Orchard Road's red hot - and it's not about the sales
Skyscrapers, carbon emissions are making city centre hotter, says study
By Radha Basu
A NEW university study shows temperature differences between Singapore's urban core and its greener suburbs to be significantly higher than previously believed.
And with the urban sprawl spreading, much of Singapore may end up as a concrete cauldron - unless measures are taken soon to reduce the heat, say the researchers.
The study found that night-time temperatures in downtown Orchard Road were up to 7 deg C higher than those in Lim Chu Kang, the closest Singapore has to a rural hinterland.
The maximum temperature in Orchard Road was 30 deg C, while it was 23 deg C in Lim Chu Kang.
Previous studies done in the early 1980s, 1996 and 2002 had put the maximum temperature difference at between 4 and 5 deg C. But those studies monitored temperatures for a total of two weeks to a month, while the latest effort, by the National University of Singapore's (NUS) geography department, measured them continuously for an entire year.
Though cities are known to be hotter than less built-up areas, it surprised researchers that downtown Singapore, even with so much greenery, could trap so much heat, said Associate Professor Matthias Roth, who led the study.
'What's happening here is certainly a microcosm of what's happening and could happen worldwide,' he added, referring to growing concerns over global warming.
'And if we don't intervene, it will just get worse.'
A hotter city centre, scientists say, would spell trouble for rich and poor alike. Hot weather, besides being uncomfortable, is known to be a fertile breeding ground for a host of tropical viruses, including dengue.
The key culprits of the problem - referred to by scientists as 'urban heat islands' - are concrete skyscrapers and carbon emissions from air-conditioning and other industrial activities.
Concrete buildings trap vast quantities of heat during the day, which they spew back into the atmosphere at night, said Associate Professor Wong Nyuk Hien of NUS' department of building, who led one of the earlier studies.
Ironically, air-conditioning - with its compressors belching out heat - exacerbates the problem.
Prof Wong is working with the Government on ways to bring down the temperature. One is to plant more greenery around concrete monoliths to soak up excess heat.
Plants are known to absorb carbon dioxide - a by-product of air-conditioning and other industrial emissions - thus dissipating much of the heat.
One study in Japan showed that greening rooftops in Tokyo could help cut air-conditioning costs by as much as $1.6 million per day.
'Newer buildings are being designed with gardens not just at the rooftops, but also at mid-level floors,' said Prof Wong.
Nominated MP Geh Min, who has championed green issues in Parliament, said curbing air-conditioning use was another way this 'dangerous trend' could be stemmed.
'We are all familiar with the ridiculous situation where air-conditioned offices are so cold that we need to wear cardigans and shawls indoors.'
