Property consultant Ho Wai Man, 54, leads a team that has worked since 2009 to trim his condominium's use of resources by reducing the number of lights and turning off water features during dry spells.
He also tries to make his neighbours at Floravale more environmentally aware; so, tomorrow, residents of the Jurong West condominium will take part in Earth Hour for the second time. About 300 to 400 of them are expected to attend a low-key, candle-lit get-together by the pool. Last year, about 200 people turned up.
The neighbourhood is among a handful taking part in the annual event, which was started in 2007 by the World Wide Fund for Nature (WWF) in Sydney.
Neighbourhoods in West Coast, Hong Kah, Tampines West and Simei will mark Earth Hour by asking residents to switch off their lights between 8.30pm and 9.30pm tomorrow, and attend community get-togethers. At Woodlands and Marine Parade, star gazing has been organised.
Companies and organisations are also getting in on the act. The i Light Marina Bay light show will go dark for the hour, as will 63 buildings around Marina Bay, including the ArtScience Museum.
Supermarket chain FairPrice will turn off non-essential lights at its 120 outlets between 8.30pm and closing time. Its 24-hour stores will forgo lights until 7am.
More than 5,000 people are expected to be at The Float @ Marina Bay from 5pm tomorrow, as Earth Hour is celebrated with music performances and a carnival.
Globally, buildings like the Golden Gate Bridge in San Francisco, the Petronas Twin Towers in Kuala Lumpur, the Eiffel Tower in Paris and the Burj Khalifa in the United Arab Emirates will go dark for an hour.
Property company CapitaLand Group said non-essential lights will be turned off for the hour or more in its 230 buildings in 20 countries.
Last year, about 345 million people in more than 154 countries and 7,000 cities marked Earth Hour. The event's carbon footprint will be monitored and offset against carbon purchases, said the WWF.
But Earth Hour was always meant to go beyond the day's festivities. It "started out as a lights-off campaign, but always dreamed of being something much bigger", said Earth Hour Global co-founder Andy Ridley.
WWF Singapore chief executive Elaine Tan said people here are asked to pledge to raise air- conditioning by 1 deg C, use lower-energy LED lights and fewer plastic bags and take shorter showers. About 20,000 such pledges are expected this year, 43 per cent more than the 14,000 made last year. These include pledges by Marina Bay Sands, Singapore Post and furniture giant Ikea.
Awareness is crucial as Singapore's carbon footprint increases with the size of its economy. So how effective is Earth Hour?
Assistant Professor Sonny Rosenthal, an expert on environmental communication at Nanyang Technological University, said: "It's probably one of the best-known environmental campaigns, involving millions of people around the world every year.
"So in terms of name recognition and getting people to do that one little environmental action, it's very successful."
But that may not necessarily translate into more, he said.
Still, Earth Hour can help community members like Mr Ho introduce others to sustainable behaviour, added Prof Rosenthal.