Traditional incandescent light bulbs waste a lot of their energy by turning energy into heat rather than light itself. Energy saving light bulbs work in the same way as fluorescent tubes - an electric current passes through gas in a tube, making the tube's coating glow brightly. This means they use less energy and are cool to the touch.
Although energy saving light bulbs cost a little more to buy than their old technology equivalents, they save you money in the long run by reducing the amount of electricity you use.
The chart below details the annual savings you can make on your electricity bills per light bulb. It also shows the difference in CO2 emissions between standards and energy saving light bulbs, and what this means in terms of environmental impact.