Dimmable compact fluorescent light bulbs have arrived. Dimmable CFL and LED bulbs are available for all conventional screw and bayonet spotlight and downlight fittings, meaning we can all save money on our electricity bills.


Governments all over the world are trying to reduce carbon dioxide emissions. One of their targets is to reduce the amount of electricity people use to light their homes. Subsidies and tax changes are being used to encourage people to switch to more efficient types of lighting. As electricity prices go up year on year, more people will be willing to invest in lighting systems that have a higher initial cost, but lower running costs.


The Recent Past - The Traditional Incandescent Light Bulb


This works by passing an electric current through a coiled tungsten wire filament, which becomes hot because of the wire's high resistance and, incidentally gives out light. These are very inefficient and use lots of electricity to produce the light we want. Most of the electricity used is converted to heat energy and very little to useful light energy.


Incandescent, filament, bulbs almost instantly give out their maximum light, though it is noticeably more yellow than daylight. This is what we are all used to and it is the standard against which any replacement technology is measured. Filament bulbs can be used with dimmer switches.


Today's Technology – CFLs and LED Bulbs


Compact fluorescent light bulbs (CFLs) use a small, coiled fluorescent tube, sometimes in an outer, opaque shroud, sometimes bare. All fluorescent tubes work by vaporising a tiny quantity of liquid mercury, which then allows the electricity to pass through it in the vapour phase that makes the white powder coating on the inside of the tube fluoresce.


CFL lights use only a fifth of the electricity of a conventional argon filled filament light bulb to give a similar amount of light. The cost of CFLs has fallen as the technology has become mainstream but there are concerns.


CFL bulbs take up to a minute to reach full brightness and when we compare it to a filament bulb we find this unsatisfactory. The light is still more yellow than daylight, but less so than a filament bulb. Most CFLs cannot be used with dimmer switches.


The main concern is a more serious one, which is not being addressed.


Companies exist that make bulk collections of failed fluorescent tubes from industrial and commercial premises in order to recycle the mercury. Domestic fluorescent tubes (including CFLs) are usually just thrown out with the trash, meaning that the mercury they contain evaporates into the atmosphere. Mercury vapour is poisonous and causes damage to the brain and central nervous system of all animals, humans included.

Light Emitting Diodes Bulbs (LED Bulbs) are a younger technology than compact fluorescents. LEDs (light emitting diodes) are electronic components that emit light when electricity is passed through them. They reach full brightness instantly and give a very white light. The main disadvantage to LED bulbs is that the light LEDs give out is directional. Early LED bulbs have proved unsatisfactory in that they only give light immediately below the bulb, rather than illuminating a whole room.


LED bulbs use only a tenth the electricity that a CFL bulb does to give a similar amount of light, so adopting LEDs will save us all money in electricity costs and reduce national carbon dioxide emissions further. Early-type LED bulbs cannot be used with dimmer switches.


LED bulbs are very expensive to buy and most people are not willing to switch to LED lighting until the costs have fallen to CFL bulb levels and until bulb design has improved. These changes are now in the pipeline as LED bulbs become mainstream in the same way as CFLs did a few years ago. Prices will fall as large light bulb companies apply their mass production and distribution systems to LED production.


LED bulbs are now on the market that can be used with dimmer switches. This has proved a major obstacle to the uptake of CFLs, even though dimmable CFLs are now on the market, at a cost. Dimmable LED bulbs are becoming mainstream earlier in our adoption of LED technology, so LEDs are likely to be our main lighting technology for the foreseeable future.


Tomorrow's Technology


LEDs will replace both CFLs and filament bulbs totally within ten years. It is only poor bulb design and high costs that are preventing people adopting LEDs. These will both improve, which together with the instant start-up of LED bulbs and their bright white nature will ensure a greater acceptance of LEDs than CFLs have ever had.

Full spectrum daylight lights are already available in LED bulbs and perhaps as technology falls in cost Seasonal Affective Disorder will become a thing of the past.

Compact Fluorescents have been a transition technology that has nearly served its purpose. Light emitting diodes represent the future of lighting.


Where Should You Use Dimmable CFLs?


Dimmable CFLs can be used in any room where you require varying light levels, perhaps for watching TV in a family room. They can be useful in a young child's room, where the light needs to be left on overnight.


Where Should You Use Dimmable LED Bulbs?


Dimmable LEDs will eventually be used in every application, but their current high cost limits their usefulness to replacing the high wattage halogen lights used in spotlights and track lighting.


Many people use halogen spotlights without ever being aware of their running costs. They are misled by advertising claims that they are now more efficient than they used to be. This claim may be true, but the efficiency gains are small and they still consume roughly the same amount of electricity as a filament bulb.


Replacing halogen spotlights with PAR 30 dimmable LED bulbs will give you massive savings in your electricity bill and that will soon repay the initial cost of the bulbs.


GU10 bulbs are used in flush fittings for recessed ceiling lights. Early GU10 LED bulbs were totally unsatisfactory, giving only a fraction of the light given out by CFL GU10 bulbs, which were themselves unsatisfactory replacements for halogen GU10 bulbs. Dimmable LED GU10 bulbs are now available that work well as replacements for the original halogen GU10 bulbs.