IT'S 24 hours to go - and Southampton's biggest shopping centre is counting down the hours until darkness descends in the Earth's biggest blackout.

The Southampton shopping mall is among the landmark buildings around the world turning off the lights for one hour on Saturday night. Other iconic structures taking part in the big switch-off include Sydney Harbour Bridge, the Golden Gate Bridge in San Francisco and Portsmouth's Spinnaker Tower.

It is hoped that the blackout in major cities across the globe will save energy and raise awareness of climate change.

Southampton's skyline could look very different during Earth Hour as familiar buildings around the city turn off their lights from 8pm.

The Mayflower theatre, the Civic Centre and clock tower, the Skandia building and the Daily Echo's headquarters will all be plunged into darkness along with Hampshire Constabulary's HQ, Hampshire County Council's offices and Winchester Cathedral.

Householders are also being encouraged to join the blackout, which created a ten per cent energy reduction in Sydney when the scheme was piloted there last year.

A WestQuay spokesman said: "We feel it is incredibly important to support an event like this to raise awareness of the issue of climate change by encouraging people to stop and think about all of the energy wasted every day.

"We have encouraged all retailers within WestQuay to switch off their display and non-essential lighting, as well as all our employees to do their bit and turn off their lights at home."

The shopping centre - which uses a renewable energy provider - reduced its energy consumption by 12 per cent last year and hopes to increase that saving to 31 per cent in 2008.

Meanwhile, the Art House cafe in Bedford Place is hosting a pre- Earth Hour event tonight, including a candlelit sing-song and poetry readings.