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, so they are a very wasteful way of lighting your house.
Compact fluorescent light bulbs
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 can pay back their higher initial cost several times over. They also save you the hassle of having to replace bulbs so often.
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.
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.