Cutting carbon emissions through reducing energy consumption may not be as effective as it seems, if consumers spend the money they have saved on environmentally unfriendly products, an economic think-tank has warned.

"If someone saves money from having cavity wall insulation put into their house, but then spends it on something which produces carbon emissions in its manufacturing, or takes an extra journey, then the environmental benefit is lost. "You have to think about what the effect is all the way down the chain - that if you use less, you might actually end up consuming more." Mr Timar warned that people who had saved £100 by cutting their energy bills could use the cash to fund extra leisure activities, such as drinking imported alcoholic beverages in bars - or electronic gadgets, which are often shipped from overseas.

It has been calculated by environmental experts that one single bottle of imported beer uses 900g of CO2 - wiping out two-thirds of the annual carbon savings made by replacing all light bulbs in an average home with energy-saving models.

A think-tank discovers that people spend money – and it makes Gaia cry:According to PricewaterhouseCoopers partner and renewables specialist Michael Timar:This is beautiful:Drink two and you’re in credit.