![]() ![]() The efficiency of a luminaire depends on two factors: But the amount of light that is produced also depends on the efficiency of the luminaire itself. The regulator’s focus is on the energy efficiency of the bulb. Halogen bulbs offer a yield of about 18 lumens / W – an energy saving of 20% to 40% compared to traditional bulbs. For a long time LEDs had a deserved reputation for being a bit weak, but it is now common to find affordable LED bulbs announced with the 1000 – 1500 lumens (although again, rarely with a very high quality light). The best LED models also have high yields – and they are progressing rapidly as technology advances. With light outputs of 50 to 60 lumens per W, they consume 4 to 5 times less current than conventional incandescent bulbs. The best yields are obtained by the neon tubes – which explains why they are massively used in industrial or office lighting – and by the compact fluorescent bulbs – which are miniature neon lights. The table below shows the electrical power consumed, the quantity of light emitted and the light output for a few examples of bulbs: Type & Power of Light Source In other words, quality bulbs that offer a high Colour Rendering, must be more powerful than lower quality ones, to emit as many lumens.) However the latter will provide the best light quality, and the best colour rendering. (Note for the more technical: an interesting consequence of the definition of the lumen, is that a lamp – LED for example – which emits a light of temperature of 4000 Kelvin with a narrow spectrum, will show a much better yield than another LED of the same power, emitting the same average 4000 Kelvin, but with a much wider spectrum. This yield is measured in lumens produced per watt of electric power consumed. An ultraviolet lamp for example, which emits an invisible light for the human eye, will produce a luminous intensity of zero lumen, whatever its power!Īt a given wavelength (the “colour”) and with the same electricity consumed, a bulb with a high efficiency will emit more lumen than another with a lower efficiency. The 555 nanometers correspond to a yellow-green frequency, close to the maximum sensitivity of the human eye. It is important to note that the lumen measures the luminosity perceived by the human eye, which is more sensitive to light at the center of the visible spectrum than at its extremities. Historically, the lumen was defined by its inventor (Perley Nutting at the beginning of the 20th century) as the total luminous flux emitted by a source of wavelength of 555 nanometers with an intensity of 1/683 watt (in 1979, this definition was simplified by introducing the candela, see below our paragraph on the candela). The amount of light emitted by a bulb is measured in lumen. In addition, two bulbs of the same technology can have very different yields, depending in particular on the quality of their construction and of the materials that are used. ![]() Each technology (fluo-compact, halogen, traditional incandescent, incandescent halogen, LED) shows a different performance. This transformation is not perfect, a significant proportion of the energy is transformed into heat. The meaning of the technical terms that appear in the descriptions of the modern lights: lumen, lux, candela.Ģ- Luminous power and energy efficiency of the bulbĪ light bulb is like an energy transformer: it consumes electrical power – which goes to your electricity bill – and transforms part of it into light.That lighting fixtures also have of their own efficiency.How to measure the energy efficiency of a light bulb.It explains the main parameters used to describe the characteristics of the modern lights, and in particular: If you regret the time when it was enough to read the consumption in watt on the box of your bulb to choose the luminous intensity that you needed, then this page is for you. Calculate the parameters for the lighting that you need ![]()
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