Going green could add $31bn to UK economy by 2015

* Green business accounts for a third of UK growth

* CBI sees trade gap decline by 800 mln pounds

LONDON, July 5 (Reuters) - The low-carbon products and services sector, often referred to as green business, could contribute 20 billion pounds ($31.16 billion) to Britain's economy by 2015, the country's leading business lobby said on Thursday.

"Get our energy and climate change policies right, and we can add 20 billion pounds extra to our economy and knock 0.8 billion pounds off the trade gap, all within the lifetime of this Parliament," said John Cridland, director general of the Confederation of British Energy (CBI).

But the CBI warned that if the government does not adopt the right policies the sector will not reach its full potential, putting 400 million pounds in net green sector exports at risk in 2014/15.

The CBI wants the government to meet its fourth carbon budget, which sets goals for Britain's carbon-cutting programme, to ensure its current electricity market reform gives long-term investment signals. It also wants the government to reduce complexity in low-carbon regulation.

"The so-called 'choice' between going green or going for growth is a false one. We are increasingly hearing that politicians are for one or the other, when in reality, with the right policies in place, green business will be a major pillar of our future growth," Cridland said.

The CBI estimates that over a third of all UK growth in 2011/12 may have come from green business, a market which was globally worth 3.3 trillion pounds in 2010/11.

The sector now employs nearly one million people in the UK, the group said.

($1 = 0.6419 British pounds) (Reporting by Karolin Schaps. Editing by Jane Merriman)