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Sky's the limit for roof gardens

Published on Friday, 28 May 2010
ARA Asset's roof garden in Kwun Tong.
The company’s chief executive, Stephen Chu, says ARA is turning unused areas into valuable assets.
Photo: Edmond So

When designing Hong Kong's first sky garden last year for an office tower in Kwun Tong, the design team had the sense to keep things relatively small and regarded the project as experimental. The basic idea was to convert an otherwise unused space into a rooftop oasis with grass, plants and an outdoor area where people could take a break and be in touch with nature.

The response from tenants, staff, shareholders and visitors was so positive that a second such garden has already been completed - at Metropolis Tower in Hung Hom. With more on the drawing board, the intention now is to add refinements, making each new garden a centrepiece to promote green thinking, energy saving and recycling in a much wider context.

"One thing we are thinking of is to rent [out] individual plots so that tenants can grow their own fruits and vegetables," says Stephen Chu, chief executive of ARA Asset Management (Prosperity), who is spearheading the overall initiative. "A number of tenants mentioned that this is popular in Japan, and it will allow us to offer an activity that is sustainable and practical."

Recycled rainwater, collected in a 500-litre tank and treated to reduce acidity, will be available for irrigation. Windmills and adjustable solar panels will generate sufficient electricity for power or lighting, with batteries storing any extra charge for use elsewhere in the building. A compost-making area will also be set aside to recycle organic waste and provide a ready source of high-grade fertiliser. "It is an idea we've just started to explore, but on some roofs there could be space for between 20 and 30 garden plots," Chu says. "For us, it is a way to turn unused areas into valuable assets and to add to the attraction of the building. Nowadays, these things can be a tipping point for tenants when they are deciding whether to move in or go elsewhere."

ARA's green committee will push the plan forward as part of its broader role to promote environmental awareness and the company's own "4R" policy - reduce, reuse, recycle and rethink. The committee found that, once people commit to these principles and use a little imagination, there is nearly limitless scope for change and improvement.

The committee's basic approach is to go floor by floor and process by process, questioning practices and implementing greener solutions. These include installing motor sensor switches to cut electricity consumption, having self-closing doors to lessen cool air leakage, controlling air conditioning units with climate sensors and using tinted glass to reduce the ambient temperature in offices.

Other initiatives are less technical. They may involve having more plants in common areas or making better use of natural light. "We want to encourage behavioural changes at institutional and individual levels to lessen the impact of [business] operations on the environment," Chu says. "By doing things that are just common sense, we can make an incremental difference and achieve significant cost savings."


Power plan  

Through its green initiatives, ARA has discovered that:

  • one rooftop windmill can provide 400 watts of electricity per hour
  • a standard solar panel can generate 50 watts per hour to charge batteries
  • for a typical commercial building, air conditioning accounts for about 70 per cent of utility costs


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