The most common type of energy-saving light bulbs are called compact fluorescent lamps (CFLs), and most are designed to replace incandescent bulbs. They fit into the same light bulb socket, making the switch to energy-saving an easy task.
The most common CFLs used today, which have a spiral glass tube, were invented in the 1970s when oil prices shot up and electricity became more expensive. Although the company GE owned the design, they did not produce the new light bulbs. They thought building the factory for making the bulbs was too expensive. It wasn't until 1995 that the design was leaked to other companies, with China starting the mass production of the bulbs.
When CFLs first went on sale, people did not like them because their light was too cold, or white, compared to the cosy yellow glow of an incandescent bulb. However, newer CFLs now provide a more yellow glow, making them more suitable for home use. CFLs cost a little more than incandescent bulbs, but they can save a lot of money in the long term. A CFL uses up to one-third less electricity than an incandescent lamp. They also last anywhere from eight to 15 times as long as incandescent light bulbs. CFLs also produce far less heat than an incandescent bulb, which can help in a place like Hong Kong where we want to keep our homes as cool as possible.
With an ordinary light bulb, only 10 to 12 per cent of the energy it uses goes to generate light. The rest of the energy is wasted as heat. A CFL is about four times as efficient, using 40 to 50 per cent of the energy to make light. Therefore you only need a 25-watt CFL to replace a 100-watt incandescent light bulb.
If you use CFLs instead of incandescent bulbs, you can save about 7 per cent off your electricity bill.