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.