The grass is greener on the upper side

National Parks Board hopes a study on rooftop gardens will motivate people to landscape Singapore's skyline

By Alicia Yeo

SINGAPORE'S buildings will be greened up and cooled down when vine-covered walls and rooftop gardens replace bricks and tiles in the future.

This vision of an even-greener Garden City has moved a step closer to reality with the start of a study on how to 'green up' such surfaces on mid-level buildings here.

The National Parks Board (NParks) has commissioned the National University of Singapore (NUS) to look at the effects of green roofs, how they are used and what the best plant species and soil types for this climate are.

Researchers will also address problems associated with greenery, like mosquito-breeding.

The study to work out the 'how-tos' of greening buildings here is in line with the Government's move to encourage high-rise gardening in Singapore.

According to German professor Manfred Koehler, it is not difficult to grow plants on roofs and walls.

The landscape architect, who has studied urban ecology for 20 years, said that green surfaces are less expensive than tiled roofs in the long run because they last longer. All that is needed is a flat, waterproof base and a layer of light soil.

'Since the 1900s, houses in Berlin have had green roofs. And in Singapore, you don't need to nurture your plants carefully as they grow quickly in the tropics,' he said, noting that a lot of replanting is required in Germany due to seasonal changes.

Ms Peggy Chong, NParks' director of planning and development, said that green features could cool down the city and minimise the 'urban heat-island effect' - where the combination of concrete, mechanical and electrical surfaces on high-rise buildings affects a city's climate.

'Studies have shown that the concrete jungle in Tokyo has caused the temperature there to increase by three degrees,' she said, adding that 'it helps, when you look down from your office, not to see someone's cooling tower, but a roof that is nicely greened'.

Housing Board (HDB) landscape architect Tay Bee Choo said green roofs were not uncommon here. She cited Maplewoods condominium in Bukit Timah, and Shaw House on Orchard Road as examples.

In the public sector, the new HDB flats at Punggol 21 feature two 'green carparks', Madam Tay said, where pergolas - trellis-like structures entwined with creepers - add a layer of green to the estate.

NParks' Ms Chong added that once the NUS study was completed next June, a seminar would be held to present the research to the construction industry to encourage developers to start greening their buildings.

She said: 'We have all the materials needed for green roofs, but a lot of builders are still afraid of the idea. The seminar will help address their worries about things like workload and costs.'

But where there are plants, there will be insects. Prof Koehler said that researchers here must work with entomologists to solve the problem.

Said Ms Chong: 'They are part and parcel of the outdoor experience. The trouble is, people want to see lovely greenery, but they don't want creepy crawlies in the house.'