The bulbs with ignition source (classical or standard ones) are by the energy point of view the worst form of lighting, because they use only 5% of its total energy amount for creating light, and the rest is transformed into heating.
But, there are, also, bulbs which use their energy more rationally. It is important to know the purpose of a certain bulb, having in mind that the light is not defined just by the power of lighting, but by the temperature of the light.
The best kind of light is the one which is similar to the sun-light, to which our sight is accustomed. But, for certain appliances, like for example outdoor lighting, temperature of the light is not important, so the outdoor lighting, whose only function is to provide visibility, is in the most cases yellow and of inferior quality. Those sodium lamps are the most affordable. The light sources which can replace standard bulbs, the most economical ones are fluorescent ones, whose efficiency is 5 times greater than the standard bulbs. For example, 50W fluorescent bulb can replace the 250W incandescent bulb, and besides saving energy it gives high quality light.
That is why the price of the fluorescent bulb is much higher than the standard bulb. On the other hand, its durability is 20 times higher, so for the energy and financial point of view it is more affordable. The problem with the fluorescent bulbs is that they require special kind of fixtures. They are energy saving bulbs that work on the same principle, and they be connect on the same fixtures as the “regular” – traditional bulbs.
Energy saving bulbs or compact fluorescent ones use 5 times less energy power than the traditional bulbs, but its lifetime is a bit shorter than the lifetime of fluorescent ones (up to 15000 working hours or 15 times longer than the traditional ones).
It is important to emphasize that compact fluorescent bulbs have many variations and that they differ in price. Their saving power possibility and the quality of light is not an issue, so it is better and more affordable to buy energy saving bulb of an attested manufacturer, despite the higher price. Halide lamps are also better than the traditional because they are appropriate for table lamps and projectors. They are 50% more affordable and last much more.