Most of the compact fluorescent light bulbs sold in British shops are heavily subsidized by the large electricity companies as part of their obligations to encourage energy efficiency. Bulbs sold for £1 or less would be over three times the price without this subsidy. The electricity companies focus their effort on a small range of standard ‘GLS’ bulbs (the round traditional shape). Many households have now completely switched all their GLS bulbs to energy-efficiency equivalents but still have many unconventional sized fittings using incandescent bulbs. The householders may not even be aware that almost all incandescent varieties can now be replaced by energy-efficient bulbs of the same shape and power. (Debate persists on whether these bulbs genuinely deliver the same quality or quantity of light.)

As far as I know, the local community in Charlbury, Oxfordshire was the first to see a way of showing householders the full range of energy efficiency bulbs on offer. The local Community Action Group (www.cagoxfordshire.org.uk) bought a range of about 80 bulbs, put them in a couple of suitcases and lent them out to anybody who wanted to borrow them. Each bulb had a price on it and could be bought from a local retailer.

Many other places have copied Charlbury’s idea. I’ve helped set up one in north Oxford. Here are some comments on our experience:

• The best-selling 80 bulbs probably cover about 95% of all household needs.
• The library needs to contain large numbers of different small ‘candle’ and large ‘reflector’ bulbs. These are the most difficult to obtain reliably elsewhere.
• Many people also want to try out dimmable compact fluorescents. These are relatively expensive.
• You also need to carry a range of new LED bulbs.
• Suitcases to carry the bulbs are a bad idea. The bulbs – still in their packets – get banged around and damage occurs.
• The bulbs are broken, or simply no longer work, when in householders’ homes. You will need a system for replacing the defective bulbs. Don’t blame the users: the repeated movement of the bulb in and out of lamp fittings causes unusual wear and tear.
• The best way to show the bulbs is by buying a sheet of foam plastic and cutting out holes into which the individual bulbs can fit.
• The library should then be fitted into a robust metal case (or cases).
• The user should be able to buy all the bulbs in the cases from one site. We tried to use two different suppliers and it didn’t work very well. Even if your chosen internet retailer is not competitive across the full range of bulbs it seems to avoid confusion if you just stick to one supplier.

Buying a Library rather than creating it yourself
Efficient Light (www.efficientlight.co.uk) sells three different libraries, ready to be lent out to householders. They are priced at £80, £150, and £290. The company offers a discount of 15% on all purchases of individual bulbs, which can be split between the final customer and the operator of the library.

The largest library from Efficient Light contains dimmable bulbs and LEDs. Light-bulb Libraries will all need to contain an increasing range of LED bulbs, which use very little electricity even compared to compact fluorescents.

More on LEDs
2010 will see increasing interest in using LED bulbs to replace halogen bulbs in kitchens and bathrooms. (I’ve been saying this for three years now, but I promise you again that 2010 is the year LEDs finally take off.) The new Econic range from Philips offers excellent light quality to replace 240-volt bulbs, but the company has yet to bring out a low-voltage (12V) equivalent. If you buy 12-volt LEDs you will need also to get hold of new LED-specific transformers to replace the existing transformers in the ceiling cavities. LEDs are also still very expensive – at about £25 for the best bulbs – but the energy savings over their very long lives will more than compensate for the higher initial cost.

Why you should think about setting up a Library

• The Library can provide an early focus for community groups seeking to get started on carbon reduction initiatives.
• They can really help persuade people that energy-efficient equivalents do exist for even the most unusual fittings.
• An energetically run Library can provide a reasonable commission income to community groups.
• They will help reduce electricity use in most people’s homes. Although lighting is only about 20% of UK domestic electricity consumption, energy efficient bulbs can provide a noticeable saving.

Image source: Taiga Company.

1) If you buy just one new appliance in 2010, make it a really efficient fridge-freezer. The improvements in the energy use of the best fridge-freezers have been really impressive in the last few years. If you have an old refrigerator, it may be responsible for as much as a sixth of your electricity bill. A good new machine might use less than a half as much power, particularly if it is not too large. A second benefit is that by choosing to buy a really efficient refrigerator you will be sending a clear signal to the manufacturers that energy consumption matters. An impressive new web site – www.energytariff.co.uk – allows you to compare the electricity used by almost all the appliances currently in UK shops. You can make well-informed choices from your computer.

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2) Buy fewer, better clothes that are easy to wash. The worldwide textile manufacturing industry is a major user of energy. Additionally, growing natural fibres such as cotton or wool creates substantial volumes of emissions. A light woollen sweater might be responsible for over 40 kilograms of emissions before it gets to the shop. Even a T-shirt can embody over 6 kilograms of CO2 and other greenhouse gases. The average Briton buys seven of these a year. Could you make do with buying fewer, and making sure that they last longer? Buy organic cotton and you also know that your garment hasn’t added to the serious problems of pesticide pollution in central Asia. Can you switch to man-made fibres for some of your clothing? These fabrics generally last longer and can be washed at low temperatures, using less energy.

3) Think about trading in your car for membership in a car-share club. If you are typical, you use your car for one hour a day but pay for all 24. A car sitting at the kerb has to be insured, financed and maintained even if you hardly use it. Commercially run ‘car clubs’ are growing fast in many cities. They offer rentals from as little as £3.95 an hour or cars can be hired by the week from locations within a few minutes’ walk of your home. Car clubs reduce the cost of motoring for many people and each rented vehicle takes several private cars off the road. If there are no clubs in your area, simply sharing a car with neighbours may be a good alternative.

4) Look at the costs and benefits of putting solar panels on your roof. In April next year the government is introducing a new scheme to persuade us to generate our own electricity from photovoltaic panels. For every unit of electricity produced, the householder will get paid over 36p, around three times the price we are currently paying the electricity company for the power that we use. Solar panels are also coming down in price, meaning that on south-facing roofs in southern Britain you can expect a financial return of about 7% a year on your investment. It isn’t riches, but it certainly beats the interest you can get in a bank. Equally important, families that generate their own electricity seem to become more conscious of their energy consumption and focus successfully on cutting all their utility bills.

5) Eat less beef. The intensive rearing of cattle is a major contributor to greenhouse gases. These animals produce methane in their digestive processes and slurry heaps also generate large amounts of this powerful global-warming gas. What’s more, cows on most farms are fed large amounts of maize and other feed during the winter months. Growing these grains took energy and considerable amounts of artificial fertilizers. And as more and more of the world’s population demands meat in their diets, the pressure to cut down forests to create open pasture land increases. Perhaps 20% of the average Western carbon footprint is created in the food production chain and reducing the amount of beef eaten is an important step you can take to reduce this figure.

6) Try the new energy-efficient lights – LEDs. Many homes have replaced all their larger bulbs with energy-efficiency fluorescent lights. But many homes still have tens of halogen bulbs in kitchens and bathrooms. They use a lot of power and regularly need replacing. A new technology – LED lighting – uses only tiny amounts of electricity and directly replaces the small halogen downlighters. It’s only really in the past year that LED lights have become realistic alternatives. Before, they tended to have an unattractive blue colour and not produce enough light. But after recent improvements, now is the time to try some in your kitchen. They’re not cheap, but they’ll save significant amounts of electricity and will last for decades.

7) Keep your electronic devices for longer. Some of Apple’s fancy new computers have footprints of about half a tonne of CO2. This may be substantially greater than the CO2 produced generating the electricity that the computer uses in its lifetime. This could also be true for your new phone or your laptop. Although no one argues that you should waste power by unnecessarily leaving your gadgets on, the main focus should be on keeping them for longer. Doubling the average lifetime of our PCs and mobile phones would have a much more important impact than always turning them off at the mains socket.

8) Get better central heating controls. We all know that houses should be better insulated and have more efficient boilers. But for some households it may be simpler and less expensive to improve the heating controls. Check that all the household radiators have thermostatic valves. Make sure that they are turned off in rarely used rooms. Should your central heating be programmed to turn off earlier in the evening? Can you install a new computerised thermostat, such as the Dataterm (www.warmworld.co.uk), which will intelligently work out when your heating needs to be on or off? Running your heating with more care can save at least as much as investing in a new boiler. It doesn’t necessarily require you to run your house at a lower and less comfortable temperature.

9) Use the train to get to your holiday. Why not catch a train to the Mediterranean rather than driving or flying? The trip from London to Marseille can take as little as six and a half hours and you get to see something of France on the way. Book in advance and the one-way price is only £62, no more than a typical air fare. It’s similar with train travel in the UK. Going to popular UK holiday destinations by rail will almost certainly save you time and money and you can usually hire a car at the resort when you need it. Not flying to your holiday destination will probably reduce your carbon footprint by at least as much as any of the other choices in this list.

10) Grow some of your own food. Enthusiastically cultivated, a standard urban allotment can provide all the vegetables for a family of four for half of the year. In our household, we’re still eating home-produced tomatoes and lettuces grown under cover. If these vegetables had been grown in a heated Dutch greenhouse using large amounts of artificial fertilizer, shipped in a refrigerated lorry to a huge warehouse and then sold from an open chiller cabinet in a supermarket to which we’d driven, the carbon cost would be a thousand times greater. The advantages of local food are sometimes exaggerated: the greenhouse gas cost of South African apples may be no greater than English fruit kept in a cold store for months. But the footprint of seasonal produce that you grow yourself is tiny, and may even help wean your family off processed food.

11) Support international agencies trying to decrease the worldwide growth of population. The world now has over 6.7bn people, probably rising to well over 9bn by 2050. Each additional person adds to the strain on the planet’s ecology. Mike Berners-Lee, a leading researcher on carbon footprints, says in his new book, How Bad Are Bananas?, that a baby born today will add almost 400 tonnes to the UK’s emissions over his or her lifetime, even if we reduce greenhouse gases as fast as the government intends over the next decades. Cutting population growth is a vital part of any global strategy for averting the worst effects of global warming. In countless places around the world it has been shown that improving women’s education and giving easy access to family planning helps reduce the number of children in each family. As well as reducing fossil fuel use and minimising forest loss, we must therefore help women in poorer countries manage their own fertility.



A shorter version of this article appeared in the Sunday Times on 29 November 2009.

Let’s face it: energy efficiency is boring when compared to the (relative) excitement of developing new sources of low-carbon electricity or heat. The popular science magazines are full of articles on new forms of solar panel and the latest designs for wind turbines. Improving the insulation of ordinary homes, shifting to LED lighting or increasing the take-up of heat pumps rarely command the attention of editors.

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In a breathtakingly elegant paper in Energy Policy, Jonathan Cullen and Julian Allwood of Cambridge University try to persuade us just how wrong we all are.[1] The theme of the paper is that carbon emissions are far more responsive to changes in how we use energy than in how we generate it. They say that it will be cheaper, easier and quicker to make efficiency savings than to switch to renewable electricity or heat.[2] The scale of the loss from the raw energy value of a fossil fuel to its eventual productive use is enormous and the authors argue that cutting this gap is a far easier task than replacing the 50,000 fossil fuel power stations with millions of wind turbines and vast solar power plants strung across deserts to meet our emissions reductions estimates. Are they right? This article uses the Cullen/Allwood paper to look at the total potential saving that might reasonably be obtained in the next couple of decades if we make a determined effort to improve energy efficiency.

My very tentative conclusion is that we can look for a 40% reduction in current energy use if we pursue efficiency objectives enthusiastically. (I don’t look at the impact of economic growth in developing countries and the way this might substantially increase total energy demand.) Perhaps surprisingly, the cost of achieving even a 40% energy efficiency gain looks high to me, particularly compared to the cost of decarbonising electricity generation. Wind turbines probably give a better return on investment.

The background data for the Cullen/Allwood paper is not complex or controversial. The world uses about 475 exajoules a year, all but 100 of which are from fossil sources. Their contribution comes from rigorous quantification of how these energy sources are turned into things that we actually desire. First, the primary sources of useful energy are processed – usually burnt – in a variety of machines, such as a diesel engine or an oil burner. The eventual result is motion, steam, useful heat or cool, and the transformation of materials (turning ore into metal, for example). These things then deliver what human beings want – personal transport, a comfortable home, the ability to communicate, clothes and food.

What is an exajoule?
A exajoule is a unit of energy. Therefore it can be converted into, for example, kilowatt hours, which is another way of describing an amount of energy. To be a really useful measure, an exajoule will usually need to be expressed as a number for a particular period of time such ‘exajoules per year’.

475 exajoules, the world’s yearly use of energy from primary sources such as coal and oil, roughly translates into a continuous power use of about 5.5 terawatts. To put this figure into context, this is about 120 times the average electricity demand on the UK power grid. 5.5 terawatts spread over the world’s population is about 2 continuous kilowatts a head, or about 17,000 kilowatt hours a year. For comparison, the UK continuous power usage is about 5 kilowatts a head – two and a half times as much – and therefore approximately 42,000 kilowatt hours a year.

The paper sets up a four-stage chain. Fuels are extracted or, in the case of renewables, collected and then converted in a machine that turns them into heat or other useful energy source. The process occurs in what the authors call a ‘passive system’ such as a vehicle or a hot water system. The final service is something directly desired by the individual consumer or business, such as transport or comfort. There are efficiency losses in this stage in the chain.

The paper estimates the volumes of energy being used by the world’s major energy conversion devices. The top six machines are as follows:

Table 1

These machines are directed towards producing about 233 exajoules of heat a year and about 175 exajoules of motion. The energy for motion will be accompanied by heat. For example, a car’s petrol engine produces far more heat than energy for motion. So, in the case of a diesel engine, the world’s most important energy conversion device, only about 25% of the chemical energy in the fuel gets turned into energy to move the car.

The service provided by the energy can then be described. Table 2 shows the useful things we get from the 475 exajoules each year.

Table 2

Let’s look each output in turn. How much can we expect to be able to save through well-understood energy efficiency options? (Almost all of the figures in the following section are my estimates and are not from the Cullen/Allwood paper.)

Thermal comfort
Few buildings anywhere in the world are particularly well insulated. The typical British home loses around 250 watts per degree Celsius of temperature difference between the outside and the inside of the house. This means an average input of heat of around 200 kilowatt hours a year per square metre of space, compared to best practice (Passivhaus) levels of less than a tenth of this figure. Say, as a simple approximation, that we tried to get UK housing down to a level of 100 kilowatt hours per square metre. This would be expensive and unpopular since it would need most brick-built houses to be clad with insulation materials. If this 50% cut was replicated elsewhere, and also applied to building cooling needs (and there is no reason why not), world energy demand would be cut by approximately 10% (19% times 50%).

Other major energy-use savings could be generated by large-scale switching to heat pumps for home and business heating. We could, in theory, push the energy needed for thermal comfort down very dramatically, but the changes to buildings and their heating systems would have to be enormous. So I have used an estimate of a 50 exajoules energy efficiency saving.

Potential saving from better efficiency: 50 exajoules?

Sustenance
The average person needs about 2 kilowatt hours in food energy a day. (When talking about food, this 2 kilowatts is usually expressed as approximately 2,000-2,500 kilocalories.) The energy efficiency of food varies dramatically by type of product. Red meat might be 10% efficient (i.e. ten units of external energy are needed to produce one unit of food energy) whereas a grain such as oats, which is not generally heavily fertilised, might be as high as 500% (one unit of fossil fuel energy produces five units of food energy – most of the food energy comes from photosynthesis). About a quarter of the calories in the US diet come from meat and dairy products and a similar fraction in most of northern Europe.[3] If this figure fell to about one eighth, or if we switched from the least energy efficient meat (beef) to the best (chicken), the savings could be 40% of total energy consumption. Of course, a wholly vegan diet would increase these numbers hugely, but I haven’t assumed this.

Potential saving from better efficiency: 40 exajoules?

Structure
The key improvements here are weight reduction in the structural materials and a move to ‘closed loop’ recycling. For example, creating metals from ore is generally an extremely energy-expensive process. Think of making aluminium from bauxite, for example. Once we have created a metal from ore, there is usually no good reason ever to dispose of it. But dispose of it we do. 50% of aluminium cans go into landfill in the UK. Even valuable metals such as silver, widely used in very small quantities in electronic devices, disappear as your mobile phone is tossed into the waste.

Almost everything can be reused several times and sometimes indefinitely; but almost nothing is. And as the world becomes virtual, physical structures (such as paper) can be replaced by digits or by transient appearance on a screen.

The Cullen/Allwood paper also mentions the importance of such things as the streamlining of cars, another way in which structural changes can reduce the total need for energy.

Potential saving from better efficiency (this is even more of a guess than other estimates): 30 exajoules?

Freight transport
Freight transport is likely to remain as a major customer for fossil fuel suppliers for many decades. The diesel engine is only 25% or so efficient at turning the chemical energy into energy for motion, but only a huge rise in the price of oil is likely to prompt a switch to electric vehicles or electrically propelled railway trains. Diesel itself may be replaced by biologically derived oils, made from oil seeds or even algae. Whether these bio-oils can be described as more energy efficient in the language of the Cullen/Allwood paper is not clear. These forms of diesel are replacing fossil fuels with photosynthesis processes but the underlying efficiency of the engine remains the same.

In the medium term, it may be possible to switch diesel transportation to vehicles powered by hydrogen fuel cells. This would save energy since a fuel cell may offer twice the conversion efficiency of a diesel engine. Only half the energy is needed for the same amount of transportation

Potential saving from better efficiency: 10 exajoules?

Passenger transport
Passenger cars may switch to electricity and to hybrid electricity/fossil fuel. Both routes offer very substantial savings. Electric cars have approximately 80% conversion efficiencies (chemical energy to energy usable for motion) compared to 20% or so for petrol vehicles. This latter figure is rising quite fast as a result of innovations in materials, drive trains, aerodynamics, and other parts of the car. So a move to a car fleet that is battery equipped, possibly combined with a hydrogen fuel cell, may offer very substantial energy efficiency savings. Greater use of electricity for long-distance transport by rail and employment of fuel cells for urban buses will also help. But nothing in sight will reduce aviation’s energy use per passenger kilometre by as much as the use of electricity for cars.

Potential saving from better efficiency: 30 exajoules?

Hygiene
The appliances of motors can be made more efficient but the heating of the water is now the dominant use of energy in ‘wet’ domestic appliances. And, unfortunately, the energy used to heat a litre of water through ten degrees is always going to be the same. It’s certainly true that washing machines, for example, can be programmed to run at lower temperatures and use less water, but the remaining savings above and beyond what is already achieved are probably not enormous.

The amount of hot water for bathing may be possible to reduce by the use of water-saving showers, but the savings are probably not substantial.

Potential saving from better efficiency: 15 exajoules?

Communication
It’s not clear to me that large reductions in energy use are possible. As countries develop, they are also likely to devote a large fraction of their incremental national income to this category so total energy demand may rise, though this is not relevant to our estimate.

Potential saving from better efficiency: 10 exajoules?

Illumination
In most countries of the world illumination comes by the burning of fats and oils. Only in rich countries does a reasonable fraction of fossil fuel energy get employed in providing lighting. In these places, the switch away from incandescent bulbs to more advanced light sources is moving rapidly. A compact fluorescent in the home will typically be four times as energy efficient as the older technology (in terms of lumens per watt of electric power). LED bulbs, just now beginning to come into use, may introduce another four-fold improvement in efficiency. LEDs are also useful in many non-domestic applications such as street lighting, car headlights, and traffic lights.

The scope for a large percentage change in energy use is high, but the absolute amount of the saving in energy is not as large as, say, thermal comfort.

Potential saving from better efficiency: 10 exajoules?

Summing up the estimates
My highly tentative estimates suggest an approximate attainable saving of about 205 exajoules out of the annual global figure of 475. This is a saving of around 40% of current energy use. Let’s call the reduction 2.5 terawatts of continuous power

How much would it cost to achieve the same reduction in fossil fuel use by decarbonising our electricity use? The same net effect as saving 205 exajoules by energy efficiency would be provided by building about 2,000 nuclear power stations or about 2.5 million commercial-scale wind turbines. The cost of 2,000 nuclear power stations might be about £10,000bn ($16,000bn) or about £10,000 per person if divided among the richest one billion people on the planet. Wind might be about the same or even slightly cheaper if we could put most of the turbines onshore or in shallow and calm waters.

£10,000 per person is a large sum, even spread over 10 years. But it is probably less than the cost of achieving the energy efficiency gains mooted in this article. Take housing insulation, for example. Simple savings from wall insulation might only cost £1,000 or so, but generally wouldn’t achieve the 50% cuts in energy use I suggested might be possible in the section above. Really deep cuts in the energy that we use to keep ourselves warm might cost an order of magnitude more. So I want to suggest that even though some energy efficiency savings are cheap – and may even have a quick financial payback at current energy prices – the argument that ‘efficiency’ is always the cheapest way to reduce emissions is not obviously true. Beyond the easy savings from getting rid of gross inefficiency, investment in low-carbon energy sources may be a cheaper way forward.


Footnotes
[1] Jonathan Cullen and Julian Allwood, ‘The efficient use of energy: Tracing the global flow of energy from fuel to service’, Energy Policy, 38.1, pp. 75-81.
[2] Two newspapers for which I occasionally write have now banned the phrase ‘low-hanging fruit’. So I don’t use it in the text even though any article on energy efficiency normally has to use it in the first two paragraphs.
[3] Most of the figures in this paragraph are from Gidon Eshel and Pamela Martin, ‘Diet, Energy and Global Warming’, Earth Interactions, 10 (March 2006), pp. 1-17.