Energy efficient lights

Lighting

Why is your regular incandescent light bulb with a tungsten filament so hot to touch? Because 95% of the electrical power goes to producing heat instead of light. They are therefore a very wasteful way of lighting your house.

On the other hand, compact fluorescent light bulbs (CFLs), which can go into the same light sockets as incandescents, generate very little heat and can thus produce much more light per unit of electrical power. Existing versions are now nearly 5 times as efficient as incandescent light bulbs. That’s why the replacement for a 60 watt incandescent bulb is a 12 watt CFL – they both produce the same amount of light. CFLs also last more than 10 times longer. They thus pay you back their higher initial cost several times over. They also save you the hassle of buying and replacing bulbs so often.

You should replace at least a few of your incandescent lights with CFLs, particularly in area where lights are on for several hours at a time, for example hallways, kitchen and living areas. A CFL will not be as cost-effective for rooms used for just short periods at a time, such as in a bathroom.

The cost of CFLs is dropping quickly and the Electricity Commission and its partners are promoting the uptake of subsidised CFLs in homes. The first phase of this promotion has resulted in consumers purchasing 1.4 million CFLs. Over their life, this will result in a reduction of CO2 emissions equivalent to taking over 18,000 cars off the road. The Commission is now targeting the installation of 3 million CFLs by the end of June 2007. This would save New Zealand enough electricity to power up to 30,000 homes, cut around $45 million from residential power bills and reduce CO2 emissions equivalent to taking 40,000 cars off the road. For more information: Electricity Commission website

Several jurisdictions have announced their intention to phase out incandescent lights completely. A bill has been introduced in California to ban the sale of incandescent bulbs by 2012. Australian officials have recently announced a phase out of incandescents by 2009. The New Zealand Minister of Energy has said that New Zealand may introduce a similar programme. Lighting industry associations are also joining the cause. For example, the European Lamp Companies Federation, a trade group of lighting manufacturers in the European Union, unveiled a pact to phase out incandescent bulbs, but have not yet specified a deadline.

One issue with CFLs is that they contain mercury – anywhere from 3-10 milligrams per bulb. Incandescents don't. CFLs must be disposed of properly or the toxic mercury could escape into the environment. In recognition that CFL disposal could pose a problem, major manufacturers are promoting bulb-recycling programmes and plan to cut bulbs' mercury content.

Halogen lights are becoming especially common in homes these days, both in recessed fittings and in free-standing and table lamps of all kinds. They are not nearly as efficient as a CFL but they are around 1.5 times as efficient as an incandescent light bulb and last longer. So, if you are purchasing a table or floor lamp, one that takes halogen lights is better than one with standard incandescent light bulbs. If you want to light a large space use fluorescent tubes rather than incandescent bulbs or halogen lamps. Fluorescent tubes are about the same efficiency as a CFL.

So if you are building a new home or renovating your existing home, the best approach is to use CFLs and fluorescent tubes wherever possible, and then halogen lights in moderation. In many homes there is a tendency to install large numbers of feature halogen fittings which leads to large lighting bills. Halogens that are recessed into ceilings cannot have insulation near them because it will overheat and burn. If the ceiling is insulated a hole must be cut in the insulation around the recessed light. This creates a 'sinkhole' through which heat can escape.

Bright future
Recently, solid state lighting (SSL) technology has emerged. Solid state lights consist of a cluster of white light emitting diodes (LEDs). At present, LEDs are about twice as efficient as incandescent light bulbs, but new technologies promise to make them more efficient than CFLs. Furthermore, they have a very long life span and are more mechanically robust than incandescents and fluorescent tubes.

Although, solid state lighting is becoming more available for household use it is still expensive, and CFLs fitted into standard light bulb sockets are currently the best choice for efficient household lighting.