The greening of the tops of multi-storey carparks and public housing blocks has taken root here.
Fourteen carparks and 17 residential blocks in older estates - 4ha in all - now wear crowns of green.
The cost: $4 million.
Another 9ha of such high-rise gardens are being planned for the next five years, with the top deck of the multi-storey carpark at Block 129A, Bukit Merah View, among the next lined up for greening.
Aside from being low-maintenance, these gardens reduce the glare of sunlight reflecting harshly off bare concrete roofs which residents in neighbouring buildings would otherwise have to put up with.
The gardens also make the environment cooler, and beautify the estate.
There is one crucial difference between these Prefabricated Extensive Green (PEG) Roof Systems and the rooftop gardens built in newer Housing Board estates: The public cannot access PEG gardens.
Rooftop gardens in estates built after November 2005 typically have more shrubs, trees and communal facilities such as playgrounds or fitness areas. As the weight of such facilities exact a toll on the roof, such gardens must be incorporated into the design from the planning stage, said the HDB.
PEG gardens have been retrofitted in selected blocks in older estates since 2006. They comprise a series of trays hosting hardy plants that can withstand the tropical heat.
Green roofs came about after the HDB and the National Parks Board (NParks), in a 2003 experiment, converted the top of a multi-storey carpark in Punggol into four green plots about half the size of a football field.
It was found that this reduced heat on the building’s surface by as much as 18 deg C, and the surrounding air temperature by 3 deg C. Glare was also cut down by as much as 15 per cent.
UGL Premas, which worked with the HDB on the system, said the purpose was to introduce instant, no-fuss greening to rooftops in an urban environment.
No structural retrofitting or heavy construction works need to be done to house the trays, which can weigh up to 120kg per sq m.
A UGL Premas spokesman said that by lowering the temperature of the roof and reducing heat transferred into the building, PEG gardens enable cost savings in energy that would have otherwise been used to run fans or air-conditioners.
The HDB typically bears the costs of building such installations, then hands them over to the town councils to manage.
Member of Parliament Indranee Rajah said that in response to requests by Bukit Merah View residents for more greenery, she checked with the HDB and found that a garden on top of the carpark would cost $250,000, or $110 per sq m.
She has asked the HDB to consider including a communal space in the garden, so residents can enjoy the plants up close.
The HDB is looking into it.
Housewife Kurra Madhavi, 27, who lives in a block near the carpark, said: ‘It would be refreshing to see plants rather than concrete, and I believe it is something all in the neighbourhood, especially the children, will enjoy.’
Retiree Sang Guan Shao Xin, 73, said it would be a good use of the space.
‘Nobody parks on the top deck because of the rain and sun, so why not have plants there?’
