TURNING the clocks back each winter causes a surge in Britain’s greenhouse gas emissions and adds millions of pounds to power bills, according to a new study by Cambridge University engineers.

They found that darker evenings cause domestic consumers to use an extra 5% electricity, generating millions of tons of carbon dioxide (CO2 The report will be published this week, anticipating next weekend’s turning of the clocks back an hour from British Summer Time (BST) to Greenwich Mean Time (GMT).

It estimates that remaining on BST all year – and perhaps renaming it Energy Saving Time – could also prevent 104 deaths and 450 serious injuries on the roads each year by decreasing the amount of driving in the dark. The National Health Service would save £200m a year in treating injuries associated with daytime darkness.

Elizabeth Garnsey, author of the report and a reader in engineering and business at Cambridge’s Institute for Manufacturing, said: “Our current time policy costs us dearly in bills and emissions. CO2 “Setting the clocks back to GMT is an institutional practice so well entrenched it is exempt from evidence-based policy making. No systematic evidence has been produced and no research commissioned in support of the government’s position.”

Garnsey’s report adds a new twist to an argument that has lasted more than a century.

It has long been said that Britain would benefit economically from syn-chronising clocks with its European neighbours and that people would prefer to have more daylight in the afternoon and evening during the winter. However, such moves have been stymied by concerns over the impact on Scotland, where moving the clocks forward an hour would leave northern areas in darkness until about 9am.

The years 1968-71 saw an experiment in which Britain brought the clocks forward by an hour, but MPs voted to abandon it after anecdotal evidence of morning road accidents involving schoolchildren and disruption to dairy farmers and construction, delivery and postal workers.

Garnsey’s report says such anecdotes were misleading and were not backed by any formal attempt to gather evidence. Her new finding – that putting the clocks back generates an extra surge in energy demand, carbon emissions and road accidents – is likely to reopen the debate.

A significant factor in the energy surge is that, under GMT, around 35% of the population are asleep when the sun rises in winter and so make no use of the extra daylight. Then, because they arrive home from school or work in cold and darkness, they use more lighting and heating, causing a surge in demand, especially between 4pm and 6pm.

The costs and emissions are amplified because Britain can only meet these daily surges by switching on less efficient back-up generating plants such as oil-fired power stations. Such plants can take hours to heat up and cool down, pushing the costs and emissions of such power even higher.

Garnsey did not look at the impact on demand for gas consumption but believes it would show similar trends.

The energy-saving benefits of keeping clocks forward an hour were clear to wartime politicians. British Summer Time, also known as GMT+1, was created in 1916 to save coal. During the second world war, Britain used GMT+1 during the winter and GMT+2 in summer, again to reduce fuel consumption.

Britain might have moved permanently to such a regime in 1971 but MPs voted against after an emotive debate involving claims that putting the clocks forward had caused an increase in winter morning road accidents to schoolchildren. What they were not told was that this was more than offset by the much greater fall in accidents in the evenings.

Garnsey calculates that the 1971 decision has caused an extra 46m tons of CO2 to be released since then.

There are signs that senior politicians are ready for a rethink. A spokesman for Pat McFadden, the employment minister who also has responsibility for timekeeping, said he was reading the report “with interest”.

Tim Yeo, Tory chairman of the envi-ronmental audit select committee, who earlier this year tried to use a private member’s bill to bring the clocks forward by an hour in both winter and summer for a three-year experimental period, said: “The environ-mental case for action is unanswerable.”

There is, however, likely to be powerful resistance to any change from Scotland. Alex Salmond, the first minister, said: “The current system protects the safety of children travelling to school. Not putting the clocks back would leave Scotland in darkness until 8 or 9am.”

But Sylvia Thorne, an art teacher from Sanday in Orkney, said: “There isn’t much strength of opinion about it up here. The Scottish weather is so miserable in winter that it would make little difference.”

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