UK supermarkets and DIY chains stock up to twenty different types of energy-efficient light bulbs but most households have some light fittings that cannot use any of these bulbs. There are several hundred different combinations of fitting, shape, and power. Some internet sites, such as www.lightbulbs-direct.com/article/energy-saving or www.gogreenlights.co.uk offer a very wide range of low-energy-use bulbs including many unusual types you cannot find in shops. One problem remains: it is not always possible to tell whether the bulb you see on a webpage will actually fit your lamp holder or whether it will be the correct brightness. Light-bulb Libaries may be the answer. 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.