Global warming and rapid urban development partly to blame, reports Shuli Sudderuddin
Martha Stewart, the popular American lifestyle guru who visited Singapore recently, commented on the ‘cruel’ heat.
Singaporeans who feel their country has become hotter over the years are not wrong.
According to figures from the National Environment Agency (NEA), the average temperature last year was 27.9 deg C, or about 1 deg C higher than the average temperature over the last 50 years.
The NEA said last year that it was difficult to determine how much of the upward trend was due to global warming and how much to Singapore’s rapid development over the past 30 years, but it pointed out that the rise was consistent with higher global temperature levels.
A spokesman for the Urban Redevelopment Authority (URA), one of the agencies working with the NEA, told The Sunday Times that various factors can contribute to the increase in environmental temperature, many of which are beyond Singapore’s control.
She added that to better prepare for the possible effects of climate change, the NEA commissioned a study to assess the long-term impact of climate change on Singapore up to 2100.
Associate Professor Matthias Roth, a climate scientist at the National University of Singapore’s Department of Geography who specialises in urban climatology, said the increase of about 1 deg C in the past 50 years is almost twice that observed for the global average.
He said the increase is because of global warming and the fact that the surroundings of the temperature measuring station have experienced rapid urban and infrastructure development, especially during the last 40 years.
‘The data do not represent the temperature that would be experienced if the station was located in an undeveloped, rural-like environment,’ he said.
Mr Tey Peng Kee, director of Singapore District Cooling, a Singapore Power subsidiary, said it is not possible to ‘cool the country’.
But adopting more energy-efficient practices would help lower the amount of fossil fuel burnt, and hence greenhouse gases and heat generated.
Dr Roth added that as part of the local temperature increase is due to the rapid development of Singapore, the preservation of nature reserves and small parks, liberal use of water features as well as the adoption of building and construction practices that moderate the ‘urban heat island effect’ - where a built-up, metropolitan area is significantly warmer than its surrounding area - can help cool the environment.
Indeed, as with the URA, many bodies are working with the NEA to keep Singapore’s climate cool.
The Building and Construction Authority, for example, has introduced the Green Mark scheme. Since April 2008, all new buildings and existing buildings with a gross floor area above 2,000 sq m that are undergoing major retrofitting must meet Green Mark standards.
These include energy efficiency, water conservation, indoor air quality, and the adoption of sustainable or environment-friendly materials or practices.
The URA and the National Parks Board are also working closely to extend the green cover islandwide.
Building design can help beat the heat
Building cooler buildings is one way of beating the heat, said a spokesman for the Building and Construction Authority.
This can be achieved by making fewer facades which face the east or west as the sun rises and sets in those directions, and the surfaces will be exposed to greater solar radiation. Where east- or west-facing facades cannot be avoided, windows with shades will prevent buildings from heating up.
Special building materials such as cool paint - a kind of paint which reflects a large amount of solar energy - can also further reduce the heat transfer from the outside into the interior of the buildings, he said.
Buildings awarded the Green Mark and designed to have low heat gain include One George Street and the Khoo Teck Puat Hospital in Yishun.
The Housing Board also follows rules to keep flats cool. A spokesman said cooling efforts include cross ventilation, a process in which facade openings such as windows are mostly placed facing a north-south direction as this is the prevailing wind direction here.
HDB flats are also designed with a secondary roofing system to mitigate heat gain for the topmost units. The system serves as an external skin shielding the roof slab from direct sun exposure.
In addition, the ventilated air gap between the main roof and the secondary roof slabs helps to minimise the transmission of heat through the concrete slab of the main roof.
Plants can make a difference
Growing lots of plants can help reduce the temperature. At the islandwide level, areas with dense vegetation cover are found to have lower surface temperatures, which also lead to lower ambient air temperatures, said a spokesman for the National Parks Board.
An Urban Redevelopment Authority spokesman said that Singapore has 3,300ha of parks.
When it comes to buildings, studies have shown that skyrise greenery, such as rooftop and vertical vegetation, can reduce temperatures by shading heat-absorbing surfaces and reducing heat intake into buildings. Ambient air temperatures get lowered too.
One body which has taken this into consideration is the National University of Singapore, which has adopted landscaping strategies - such as widespread tree-planting and green roofs - at its University Town project, which is under construction.
A spokesman said 188 existing trees have been conserved and an additional 1,366 trees will be planted. These efforts may reduce air-conditioning needs.
Greening helps to mitigate the ‘urban heat island effect’ where a built-up area is warmer than its surroundings.
For example, studies at Kent Ridge campus have shown that a building at Kent Ridge Road that is well shaded and surrounded by trees has noon-time temperature differences of as much as 4 deg C lower than one directly exposed to the sun and surrounded by hard areas.
The Housing Board has also made a move to enhance greenery in its estates.
Some ways to keep cool
The Building and Construction Authority implemented a Green Mark Scheme in 2005 which recognises good design practices in buildings so that they require significantly less energy and water resources, and subsequently lower the temperature in and outside the buildings.
Last year, the Green Mark scheme was extended beyond buildings to address the environmental performance of office interiors, parks, districts and infrastructures.
As part of this extension, developers are encouraged to use strategies such as providing covered walkways and the use of paving material with a high Solar Reflectance Index which enables it to better deflect the sun’s heat.
Underground malls and connectors are also good alternatives to walking in the sun.
At Orchard Road, underground connections between malls like Wisma Atria, Ion Orchard and Ngee Ann City are air-conditioned.
CityLink Mall has over 73,000 sq ft of shopping space and is fully air-conditioned at 24 deg C during its opening hours.
It connects to the Esplanade, Marina Square and Suntec City.
Said a spokesman for Hongkong Land, which manages commercial properties such as One Raffles Link and CityLink Mall: ‘Underground link malls such as CityLink are popular as they provide a comfortable alternative to walking under the sun at ground level. We see underground malls increasing in popularity.’
Apart from going underground, keeping cool in alfresco settings includes the use of contraptions such as mist fans, which work by evaporative cooling.
Water mist cooling is most efficient when temperatures reach their peak during the day and humidity is normally at its lowest point.
When the water from the mist fan evaporates, it cools the air around it. How much the temperature drops depends on the temperature and humidity in the air.
If the humidity is too high and no evaporation of water occurs, there is little or no cooling.
However, when there is a higher rate of evaporation, an ambient temperature of 36 deg C can be cooled to 27.2 deg C by a mist fan, said Mr Soh Wee Beng, project manager for Cool Mist which designed the water mist feature at the walkway along the Marina Waterfront.
Mr Johnny Tan, owner of Azzura Beach Club on Sentosa, has spent about $8,000 installing two large mist fans from Cool Mist.
‘When there’s high humidity the fans can be too wet, but when it’s hot and dry, it cools my customers - for example, those who are suntanning. At night, people also like to dance in the mist to keep cool,’ he said.
