Are LEDs Really Energy Efficient? Does it really save power?
Before this, the lighting industry has never been so beautiful. Needless to say in the industry, under the general environment and trend of energy saving, emission reduction and green environmental protection, it is an industry consensus and the general trend that LED will become the mainstream light source of future lighting. Even in the street talk of the consumer market, when it comes to lighting, although most of them know little about it, no one knows about LED. This half is naturally due to the government's strong support and promotion, and the other half is due to the advantages and charm of LED technology itself.
In the eyes of the general public, as a new type of lighting technology, LED has basically been equated with energy saving, and the only obstacle at present seems to be the price. Even in China, the price is no longer a problem (the reason everyone knows). However, are LED lamps really energy efficient? How to evaluate whether an LED lamp is energy efficient?
1. The luminous efficacy of the light source
LED (Light Emitting Diode) is a light-emitting diode, a solid-state semiconductor component that can convert electrical energy into visible light, just like the traditional incandescent and halogen lamps behind the thermal radiation luminescence principle, fluorescent lamps, mercury lamps, sodium lamps and gold lamps Halogen lamps use the same principle of gas discharge, LED itself also represents a technology, a light-emitting principle.
The luminous efficacy of a light source (often referred to as luminous efficacy): the ability of a luminous body to convert electrical energy into visible light, measured by the ratio of luminous flux to power, in lm/w.
As a new type of lighting source, LED technology is more advanced than traditional light source technology. But even so, LED technology itself has a wide range of light effects, and it is not accurate to say that LED light sources are more energy-efficient than other light sources. Not scientific. When we get along, we have to see how the other party is French, Chinese and Japanese, and the same is true for LED products.
In fact, to judge whether a lamp is energy-saving, it is far more than the technology and light source used.
2. Electrical energy efficiency
In addition to incandescent lamps and line voltage halogen lamps, other light sources need to be equipped with lighting appliances. Lighting appliances also have the problem of power utilization, that is, the ratio of the electrical energy used by the electrical appliances to drive the light source to emit light. Without considering the harmonics, the power factor λ is usually represented by cosφ. It doesn't matter if you don't understand these things. In short, the efficiency of lighting appliances usually needs to look at the power factor index.
Most brand manufacturers will also provide the system efficiency parameters of electrical appliances on product samples or single pages, as shown in the figure below, our designers can ask manufacturers to provide relevant parameters.
3. Lighting efficiency
The efficiency of lamps is easy to understand. In simple terms, it is the ratio of the light coming out of the lamp to the light emitted by all the light sources in the lamp under standard conditions, usually expressed by LOR.
LOR = luminous flux emitted by the luminaire / luminous flux of all light sources in the luminaire
For example, for an ordinary 3*18W lamp panel, the total luminous flux of the light source is 3600lm. If the measured luminous flux of the lamp is 1800lm, we say that the efficiency of the lamp is 50%.
4. Lighting efficiency
Leaving aside the light distribution and light utilization rate of lamps, and whether designers use lamps reasonably in the space (if the lighting design process is divided into three parts: light selection, light distribution and light use, our discussion today is limited to "selection". Light" part), to evaluate whether a lamp is energy-saving, it is necessary to combine the above three aspects to obtain the lamp efficiency:
Luminaire efficacy = luminous flux emitted by the luminaire/(light source power + electrical loss) = luminous flux emitted by the light source*LOR/(light source power + electrical loss)
5. Are LED lamps energy efficient?
After clarifying the criteria for evaluating whether a lamp is energy-saving or not, we can judge the pros and cons of these two lamps.
Taking a brand of 3*14W grille lamps as an example, when it uses three 14W/1200lm lamps, equipped with a single-tube 14W ballast and a double-tube 2*14W ballast, the system power It is 18+32.5=50.5W. The efficiency of the grille lamp is LOR=70%, then the lamp efficiency is 3600*70%/50.5W=49.9lm/W.
Summarize
When we are in the "light selection" part of the design, the main thing is to choose the right light source, the right electrical appliances, and the right lamps. The consideration of energy efficiency is an important aspect.
When considering energy saving in the design scheme, it is not only about which technology is used and what light source is used, that is to say, don’t think that LED will inevitably save energy, but also depends on the actual parameters of light source, electrical appliances and lamps. Samples and measurements can best see the problem.
From this, we can also see that it is very unreasonable to spend a watt of LEDs that are very popular now, because the owners purchase lamps and lanterns to buy "light", not "power". Using yuan/watt to measure LED, it is very likely to buy LED products with low luminous efficiency and no energy saving. If you only consider the amount of light emitted by the lamps, perhaps a better indicator to measure the economy is yuan/1,000 lumens, that is, how much light you buy for how much. Whether these lights are used or not is another matter.
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