Working out how many tonnes of CO2 is emitted on account of one's day-to-day actions has never been easier: an online search for a carbon footprint calculator throws up plenty.

In general, one kWh of gas produces 0.19kg of CO2, an average kWh of electricity produces 0.43kg of CO2 and 1kg of CO2 is equivalent to 0.27kg of carbon.

So, a four-bedroomed detached house built in the late 1960s, for example, that emits 6,637 tonnes of CO2 per year has a carbon footprint of 1.81 tonnes.

This month, housing minister Yvette Cooper said seven million tonnes of carbon could be saved by consumers better insulating their homes and installing new boilers.

But instead of taking action to reduce carbon emissions, why not carry on as normal and pay money to offset the impact?

There are now hundreds of carbon offsetting schemes that aim to help individuals and businesses reduce their CO2 emissions by offsetting, reducing or displacing the CO2 in another place, typically where it is more economical to do so.

They use the money to invest in renewable energy, energy efficiency and reforestation projects around the globe.

Climate Care's initiatives have included financing renewable energy cooking stoves in schools in India, installing energy-efficient lighting in South African houses and restoring a rainforest in Uganda.

Carbon Clear offers a range of packages to help consumers manage their carbon footprints, with products for motorists and frequent flyers starting at 5 pounds.

"In an ideal world, we'd tell people to stop engaging in polluting activities, but in reality that's not going to happen; people have to go on some flights, heat their homes and get to work," Jamal Gore, a director of Carbon Clear, told Reuters.

But, although they might go some way to appeasing your conscience, do such schemes genuinely work?

"These kinds of approaches are endorsed by the Kyoto Protocol, signed by 165 countries including the UK," added Gore.

"There's a lot of scientific rigour that has gone into setting up the methodology and approach."

Others, however, argue that carbon offsetting is a flawed concept -- and environmentally minded consumers would be better spending their money elsewhere.

"It (carbon offsetting) is being marketed very heavily by the likes of BP, British Airways and Land Rover," said Mike Childs, head of campaigns at Friends of the Earth (FoE).

"All these companies are sending out a very strong signal to consumers that they can continue to drive 4X4s, fly and use petrol as much as they want; that they don't have to change their life and can spend 15 pounds to rectify the damage.

"That's clearly wrong: you can't buy a reduction in emissions."

Although many carbon offset projects are "commendable, worthwhile and aid sustainability", it is a "con" to suggest they reduce carbon emissions, according to Childs.

"Supplying renewable energy to a village in India, for example, is a very commendable thing to do, but it doesn't cut carbon dioxide emissions," he said.

"And the same goes for tree planting; some offset schemes buy up forests that already exist, and although that might prevent them from getting cut down, it clearly doesn't cut carbon emissions -- and that is the challenge."

Instead, said Childs, consumers should take steps to reduce carbon emissions, such as spending money on insulating their homes and driving low-emission cars, if they must drive at all.