Scientific Alliance newsletter 3rd September 2009


A discussion of the benefits of phasing out incandescent lightbulbs and a welcome for David MacKay as chief scientific adviser at DECC.

Phasing out incandescent lightbulbs

This week saw the next step in the phasing out of traditional tungsten filament lightbulbs; manufacturers and importers are no longer supplying 100 watt or any pearl bulbs in EU Member States. By 2012, manufacture or import of all such bulbs will be banned, and consumers will instead need to rely on the low-energy compact fluorescent lamp (CFL). And this is not just another example of Europe leading the pack on environmental issues. A number of other countries, including the USA, are set on the same course.

It is undeniable that CFLs use considerably less energy and that many of their original disadvantages have been overcome. These days, you do not have to spend £10 on an object much larger than a standard bulb and then wait five minutes for it to give a decent light. Modern bulbs are quite compact, available in a range of shapes and sizes, and produce a high output very quickly.

But they are not the same as filament bulbs or the increasingly common alternative of halogen lighting. And they are not universally popular. For many applications, they are excellent, especially if lights are to be left on for a long time. However, their disadvantages – well documented elsewhere – include requiring more energy to make, containing mercury (an end-of-life disposal problem which also makes clearing up a broken one more hazardous), their inability to be used with dimmer switches, the different quality of their light and their size making them too large for many existing fittings.

The drawbacks and lack of universal enthusiasm are perhaps not surprising. CFLs are, after all, just a different incarnation of the familiar fluorescent tube lighting: low energy and fine for some purposes, but not good for general domestic use. As well as the different spectrum of light they emit, some people are troubled by their inherent rapid flickering. In a free market, people make their own choices, and if lower electricity bills and longer bulb life are not enough to make them change, there must be some good reasons to stop them.

Although energy savings per bulb may be very significant, the direct impact on household and national energy use are more difficult to fathom. For a start, if people use low-energy bulbs, they are often more inclined to leave them on for longer. The same thing happens for other energy efficiency measures. Also, it will take a very long time to phase out use of filament bulbs once they are no longer available. It is clear that many people are stocking up, and their supply could last many years. So, the phasing in of actual CFL use in homes will be a long process.

EU statistics show that lighting accounts for just under 3% of domestic energy consumption (about 10% of electricity use, but remember that much of the energy used is for heating, and supplied by gas or oil). Looking at overall energy consumption, including transport and industry, domestic lighting represents 0.76% of the total used in the 27 Member States.

But this is not the whole picture. A study by VITO consultants showed the following breakdown of lamp use in European homes in 2007:

  • 54% incandescent (down from 85% in 1995 and still decreasing)
  • 18% low-voltage halogen (and increasing)
  • 5% mains-voltage halogen (and growing)
  • 8% linear fluorescent
  • 15% CFL

So, if we assume that all remaining filament bulbs are replaced by CFL at some point in the future (unlikely, as use of halogen bulbs is likely to increase), that these bulbs are used to the same extent as those they replace and that the energy reduction per bulb is 80%, the total reduction in EU energy use would be 0.54 x 0.8 x 0.76% = 0.33%. This figure is almost certainly an overestimate, particularly as the inefficiency of conventional bulbs generates heat which supplements other forms of heating in winter. Which begs the question: is it really worth it?

Politicians are forcing a change to a particular technology which is fine for some applications but not universally liked, and which has disadvantages. In the meantime, very efficient and flexible lamps are becoming available using light-emitting diode (LED) technology. Already, they are widely used in torches and for car brake lights. As their cost comes down, LEDs will probably become a preferred option for domestic lighting as well. A similar amount of energy would be saved and consumers would be happier. The problem is that legislators are unable to tackle the big issues of energy use effectively, so go for the soft target of a high profile domestic use of energy. Like the furore over supermarket plastic bags, this is gesture politics.

David MacKay to be climate change adviser

On the other hand, there is some welcome news in the UK. Professor David MacKay of the Cavendish laboratory in Cambridge is to be appointed as chief scientific adviser to Ed Miliband at the Department of Energy and Climate Change. Professor MacKay has attracted considerable attention for publishing the book "Sustainable Energy: without the hot air".

In this – which can be bought in a bookshop but is also available as a free download at – he uses objective reasoning to look dispassionately at the real contribution that different generating technologies and energy efficiency initiatives can make to reducing carbon dioxide emissions. MacKay is convinced of the need to mitigate climate change, but less convinced that politicians are going about it the right way.

So, for example, he is widely quoted on the topic of how much energy mobile phone chargers when not in use: he sees turning them off as making such a tiny difference that it should be low down our list of priorities. Equally, be presents a cool analysis of the costs, benefits and downside of wind power, nuclear energy, carbon capture and storage and other alternative technologies and allows the reader to see the facts for themselves. Exposure of a very influential politician to such advice can only be applauded. If it translates into sensible policymaking, even better.

There will be no newsletter on 11th September. The next edition will be published during w/c 14th September.

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