Green consultancy WSP Environmental has unveiled an innovative carbon trading scheme designed to encourage its 1,000-strong workforce to limit their personal carbon footprints.

Under the initiative, staff can sign up to an internal carbon trading scheme similar to the cap-and-trade mechanism pioneered by the European Union. Each employee in the scheme has their annual carbon emissions capped at six tonnes and is provided with a spreadsheet application where they can calculate emissions from their home and transport.

Those who emit more than six tonnes have to pay five pence per extra kilo emitted, up to the sum of £100, while those who do not use up their full allowance will receive five pence per kilo under six tonnes from WSP, also up to the sum of £100.

The company said that any funds raised will be redistributed back to those staff signed up to the scheme through grants for investing in carbon-saving measures, such as insulation or energy efficient light bulbs.

David Symons, director of corporate services at WSP Environmental, said that the scheme had proved extremely successful, with a quarter of the company’s staff signing up since it was launched last month.

He admitted that the cap of six tonnes a year is pretty generous given that the carbon footprint for the average person in the UK stands at four and a half tonnes, but insisted there were already signs the scheme was driving behavioural change.

"People get an update every quarter on whether they are on track to come in under the cap or not and it provides a real incentive for people to try and limit emissions," he said. "I've already heard people say they are reconsidering flying somewhere over Christmas as they don't want top eat into their allowance. "