In the second edition of this book, I focus on the importance of embedded energy in the things that we buy. I’ve e stimated the carbon footprint associated with our main purchases, both things made here and good manufactured overseas. In addition, I have revised all the figures for energy use in the home and in our transport. The book provides figures for the typical UK resident in 2009, and now covers at least two thirds of the total greenhouse gas emissions. The purpose of the book, as in its first edition, is to provide a comprehensive reference work for those interested in understanding how individual lifestyle choices affect a person’s footprint. I believe it remains the most detailed and rigorous analysis of individual responsibility for emissions.

The main developments between the 2007 and 2010 editions

The average gas used by UK households has declined slightly between the two editions. This is despite the harsh winters (at least by British standards) of recent years. This provides some justification for optimism about the impact of the subsidised insulation programmes and possibly for the effect of improved efficiency of new domestic boilers. Tentatively, I also show evidence that the gradual rise in typical indoor winter temperatures has also reversed. This may just be a temporary effect as householders adjusted their behaviour in response to higher heating gas costs in the last few years.

Electricity use per household has remained the same or possibly risen very slightly. Although the speed of the switch to energy efficient bulbs has meant declining electricity use for lighting, the growth of the number and size of electric appliances has wiped out any benefit. The most significant change has probably been the purchase of large numbers of big screen TVs, using several hundred watts of power when in use. Although all types of new appliances now have much lower ‘standby’ power consumption, this has not completely counteracted the impact of the increasing numbers of phones, TVs, media players of one form or another and kitchen appliances. Disappointingly, I note few illustrations of really substantial energy efficiency improvements in major appliances. For example, fridges haven’t got much better in the last few years, at least as suggested by looking at the typical energy consumption per litre. The main retailers are still selling surprisingly few really efficient appliances even though substantially better machines are often available in other European countries.

Car emission trends have shown a sharp improvement. Driven by petrol prices, EU pressure, increasingly penal tax rates for gas-guzzlers and – probably – a declining interest in owning a large car just for status enhancement, manufacturers have substantially cut emissions per kilometre travelled for the typical newly sold car. This is the single most impressive change identified in the book. There’s more to come; we’ll see goo electric cars soon but engine efficiency, weight and aerodynamic improvements are still available for conventional cars.

The quality of the information available on public transport is much better than for the first edition. I have tried to show how varied are the energy use figures for different types of buses and trains. A full long-distance coach is a very efficient way to travel but an old bus clunking three quarters empty around a rural route has worse emissions per passenger than a car. There are similarly stark findings on rail and Tube transport.

I’ve dealt with aviation in a different way. Three years ago the consensus was that the impact of engine emissions at 35,000 feet multiplied the effect of CO2 about three fold. Science has become a little less pessimistic about this in the last few years and I have changed this multiplier to 2. There are still many uncertainties about the full impact of water vapour, nitrogen oxides and other pollutants emitted at high level, but nevertheless I felt it was right to change the figure. We still don’t really understand the full effects of aviation on the formation of heat-trapping cirrus clouds and it may be that the multiplier will need to be revised upwards again in the next few years. The book was written as aviation volumes were still highly depressed by the economic downturn, but this has only reversed the figure to where it was a few years ago. Britons still travel more by air than the inhabitants of any major country, with substantial effects on the global atmosphere.

I have done much more work on energy use in offices, shops and factories and these figures are incorporated in the book to provide summaries that can be used as benchmarks. As an occasional contributor, I’m delighted to report that the Guardian’s offices mean that I can no longer use the paper’s environmental performance as a case study of how bad things can get.

Moving on to ‘indirect’ emissions. The food chapter in the first edition was controversial because my final estimate was that the supply chain was responsible for about a fifth of the UK’s domestic emissions (ie excluding the emissions embedded in the goods we buy from China, Germany and elsewhere). Rafts of research since the 2007 publication have supported these conclusions and emphasised the role of methane output from farm animals and from poorly managed manure. There’s also been a huge and welcome rise in the sophistication of major companies’ approach to reducing the environmental impact of the food supply chain. Who would have guessed that Pepsi UK would become a world leader in environmental auditing or that the supermarkets would make such substantial reductions in emissions per square metre of selling space? The renewed emphasis on invisible emissions, such as the leakage of massively warming refrigerant gases is also highly encouraging.

There’s less progress to report on the environmental impact of our purchases. The gap between the two editions saw a further rise in UK imports of consumer goods from China. China typically has energy efficiency of about half European levels so our trade is responsible for an increasing fraction of our real emissions. I look in detail at the environmental impact of clothing manufacture and consumer electronics, providing the figures to justify my assertion that energy in manufacture usually substantially exceeds energy in use. So, for example, a mobile phone’s electricity consumption over its eighteen month life is a fraction of the energy used to make it. In fact, the electricity used by the phone companies’ base stations is far more important than the total energy use from charging the phones. I have written long new sections on paper, clothing, electronics, precious metals and cement. One tip: if you are thinking of buying a wedding ring, don’t read the chapter on the energy used refining gold.

As before, I have sections on household use of renewable energy and look in some detail at air source heat pumps, a technology being very widely adopted in some parts of Europe. I have also provided some figures on what I call ‘farm-scale’ wind turbines to show that the new feed-in tariffs provide a good return. Domestic PV, which I think should not be heavily subsidised in the UK because of our poor solar insolation levels, is also profitable for householders under the new tariff regime. As before, I conclude that carbon offsets are probably a bad idea and the conscientious householder should counterbalance her remaining emissions by purchasing trading certificates from the European emissions scheme from Sandbag or Ebico.

The first edition was called ‘the definitive guide to reducing your emissions’ by Fred Pearce in the New Scientist. My colleague Mark Lynas was kind enough to call this new and extensively revised edition ‘the carbon-reduction bible’. It is now available at Amazon (click on the box at the right) and in all but the smallest Waterstones.

Headline grabbing conclusions

Publishers need counterintuitive or unusual conclusions to attract attention to books. Here are some of the surprising findings from the book, as provided to Earthscan for its publicity work.

• The best single way to save electricity is to buy a new fridge.

• Precious metals (jewellery, gifts etc) have a carbon footprint thousands of times their weight.

• Natural clothing fibres (wool, cotton, viscose) are worse for emissions than man-made fibres.

• Electricity demand in the home hasn’t been affected by the recession. The growth in the number of appliances has matched all the efficiency gains of the last few years.

• About a fifth of UK emissions are embedded in imported manufactured goods. That is, Chinese imports contain several tonnes of CO2 emissions for each person each year.

• Airplanes have lower emissions per person, per mile than cars but they travel huge distances.

• The easiest ways to cut emissions are probably 1) to stop flying and b) to become a vegetarian and c) only buy second-hand clothes

• The reduction in the standby consumption of level of electric appliances is the single most impressive change since the first edition of the book in February 2007.

• The new feed-in tariffs for home renewables will generate annual returns of 8-10% on investments by homeowners.

• The best way to offset carbon emissions is to buy Emissions Trading System certificates.

• Plastic bags are an insignificant source of greenhouse gases

• Emissions from domestic gas consumption are falling, partly as the result of real improvements in house insulation.

• An individual person can sustain several hundred watts of effort for an hour. This might cost £8 an hour for an unskilled labourer. In the form of electricity, this would cost less than 10pence. This is the reason energy consumption is so buoyant and resistant to reduction: fossil fuel energy is almost unbelievably cheap

• Buses and trains aren’t much better than cars if the buses aren’t full or the trains are heavy and powered by diesel