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In some cases where there is a lack of natural light this cost can reach as much as half of the electricity bill. Compact or low-energy light bulbs are more expensive, but they last up to eight times longer and provide the same amount of light by consuming between 20 and 80% of the electricity required by incandescent lights. According to the Institute for Energy Diversification and Saving (IDAE), replacing a traditional light bulb with a low-energy one will represent a saving of more than 60 euros by the time it needs to be replaced.

A single low-energy light bulb can save 140 litres of oil or 150 kilos of coal during its lifetime. Power stations burn less of these fossil fuels and, as such, CO2 emissions are reduced.

Types of light fitting
Three types of light bulb can easily be found on the market. The traditional ones, said to have been invented by Edison, are incandescent light bulbs. They have been providing light for mankind for over a century. However, the principle they use to emit light is still the same: light is produced by making a tungsten filament white hot when the current passes through it. 

It is true that over the years the finishings and shapes have changed, but the characteristics are very similar. Without any doubt the unit cost of this type of light bulb is the cheapest, although if you compare it with others and take into consideration the relationship between the price and how long they last, in the end they are more expensive.

These light bulbs last for about 1000-1200 hours of light. After being used for this time, the tungsten filament starts to evaporate and ends up breaking or melting. In fact, what usually happens is that with use the light becomes less and less intense due to the fact that the tungsten that breaks off ends up sticking to the bottom of the bulb. 

Halogen light bulbs, meanwhile, last longer and are brighter. They are chemically treated so as not to get darker, which makes them last at least twice as long as incandescent light bulbs. There are those which work on network voltage which are usually equipped with an intensity regulator, as they can have a power of between 100 and 1000 watts. There are other low voltage ones which need a transformer because they have much less power than those at network voltage.

The inside of low-energy light bulbs is full of low-pressure mercury vapour. When the electric charge occurs ultraviolet light is produced which generates normal light when it comes into contact with the fluorescent powder covering the tube. This is the type of light bulb which has developed most in recent years.

Wide range
The main characteristic of low-energy light bulbs is their capacity to convert energy into light and not into heat like traditional incandescent light bulbs do. They fit standard sockets. Their only disadvantage is that their performance reduces in the cold, as such it is best to use them inside. 

Something that must be taken into consideration, if you are going to replace an incandescent light bulb with a low-energy one is that in order to produce the same light the latter require less wattage. On the other hand, since the birth of low-energy lights their advantageous innovations make using them increasingly profitable.

Using compact fluorescent lighting in the home can lead to 15,000 hours of light and an 80% saving. However, they have not only improved in terms of saving and duration but also in lighting levels. For example, there are compact lights with technology which can regulate their intensity without additional dimmer switches, simply using the light switch, and others which switch on at dusk and turn themselves off automatically at dawn.

Low-energy lights are particularly advisable in areas which need to be lit up for long periods, since their biggest disadvantage is that they consume more energy when they are switched on.