The Ocean Financial Centre at Raffles Place may be known for the huge green wall, about the size of eight tennis courts, that grows on its facade. Yesterday, the office building was also recognised for its water-saving features.

It was one of six buildings which were given a gold award at national water agency PUB's Water Efficient Building Certification (Gold/Silver) presentation ceremony at the Environment Building.

Among the Ocean Financial Centre's water-efficient features are systems that harvest rainwater for rooftop gardens, water-efficient tap fittings and a drip irrigation system to water plants.

These initiatives have saved Keppel Reit, the building's owner, 42 million litres of water a year - enough to fill 17 Olympic-sized swimming pools.

"The certification from PUB is testament to our efforts and will further spur us in our sustainability journey," said Mr Toh Wah San, executive vice-president of asset management at Keppel Reit Management.

Other gold award winners included hotel Novotel Singapore Clarke Quay, Tanah Merah Prison and Changi Women's Prison.

During yesterday's event, 10 other buildings, including Bugis Junction Tower and Mee Toh School, received the silver award.

By 2060, water usage by the non-domestic sector is expected to grow from the current 55 per cent to about 70 per cent, said Mr Michael Toh, director of PUB's Water Supply (Network) department.

He said: "We are encouraged that leading organisations in the non-domestic sector have responded positively to our call to build in water conservation practices into their management and business processes."

The winners received certificates from Mr Masagos Zulkifli, Minister for the Environment and Water Resources (MEWR). In his first speech as MEWR Minister, Mr Masagos lauded them, saying: "You have all done well and I encourage you to continue with the good job and share your best practices with others, and make water conservation a natural part of your business."