People who emit more than their fair share of carbon emissions are having their pay docked in a trial that could lead to rationing being reintroduced via the workplace after an absence of half a century.

Britain’s first employee carbon rationing scheme is about to be extended, after the trial demonstrated the effectiveness of fining people for exceeding their personal emissions target. Unlike the energy-saving schemes adopted by thousands of companies, the rationing scheme monitors employees’ personal emissions, including home energy bills, petrol purchases and holiday flights.

Workers who take a long-haul flight are likely to be fined for exceeding their annual ration unless they take drastic action in other areas, such as switching off the central heating or cutting out almost all car journeys. Employees are required to submit quarterly reports detailing their consumption. They are also set a target, which reduces each year, for the amount of carbon they can emit.

Those who exceed their ration pay a fine for every kilogram they emit over the limit. The money is deducted from their pay and the level of the fine is printed on payslips. Those who consume less than their ration are rewarded at the same rate per kilogram.

The maximum that an employee can earn or be fined has been capped at £100, but is likely to rise once staff have grown accustomed to the idea.

WSP, the global engineering consultancy, has been conducting the rationing scheme among 80 of its British employees for almost two years. In the first year the overall carbon footprint of participants fell by 10 per cent. The company is discussing its scheme with several FTSE 100 companies.

Three quarters of the employees were rewarded and a quarter, including Stuart McLachlan, the managing director, were fined. Mr McLachlan tried to cut his carbon footprint by buying a bike and cycling 12 miles to work from Richmond, Surrey, to Chancery Lane, in Central London. He also installed energy-saving lightbulbs, but he still exceeded his ration — and was fined £100 — because he flew to his holiday home in South Africa.

The idea of personal quotas for carbon emissions is being advocated by the thinktank the Institute for Public Policy Research. Everyone would be given a number of free “credits”, to buy gas and electricity for their homes, fuel for cars and plane tickets for holidays. Those who did not use all their credits could sell the excess to people who used more fossil fuels.

WSP is planning to expand its rationing scheme next year to cover 3,000 employees in offices around the world. However, it will set different targets for each country to reflect national average emissions. In Britain the target this year is 5.5 tonnes, which is one tonne above the national average for home energy and personal transport. The US target is likely to be double the British target, to reflect much greater emissions per person.

David Symons, co-ordinator of the scheme, said that US employees would be unlikely to join a scheme with the same ration as British staff. “The teams in the States would think they would be in debit straightaway.”

Mr Symons stayed within his ration last year by giving up his Mazda RX8 sports car and buying a diesel Peugeot 207. He met this year’s target largely because his partner had a baby and he rarely left home except to go to work.

One employee, Dan Dowling, 29, switched the mode of transport for his honeymoon in Rome from plane to train. His colleague, Emma Bollan, stopped blow-drying her hair and cut down on roast dinners. She said: “The big incentive is not the prospect of earning £100 but in trying to ensure that you don’t have to pay out.”

Several WSP staff added that peer pressure played a part in persuading them to stay within their ration.

Mr McLachlan said: “There have been some interesting competitive dynamics in the company as a result of having this transparency.”

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