Illustrative image. (Photo: Internet)

Other activities include comminucations on Earth Hour and energy efficiency to encourage society to join the campaign by turning off lights and unnecessary devices at homes and workplaces.

Started in 2007 by the World Wildlife Fund (WWF) and partners as a symbolic lights-out event in Sydney to raise awareness of climate change, Earth Hour is now one of the world's largest grassroots movements for the environment.

Held every year on the last Saturday of March, Earth Hour engages supporters in more than 190 countries and territories, all taking action to ensure a brighter future for people and the planet.

Vietnam first joined the Earth Hour campaign in 2009. Last year, the country saved more than 24,000 USD.