The comparison of Lighting Efficiency Between LED And Sodium

At the beginning of 2006, we installed our LED street lights LU4, 112W on half of the road to make the comparison with HPS 250W.

When we brought our customers to see the lights, they asked the same question,

Why with lower power consumption and lighting efficiency, LED streetlight is brighter than high power sodiums?

As so far, The efficiency of LED lighting is not so high as that of sodium. For LEDs, it is 65-70Lumens/Watt, and for sodiums, it can reach 125Lumens/Watt.

But the spectrum of sodium is more concentrative on yellow, its color temprature is as low as 2000~2500°K. Whereas the color temperature of LED is as high as 2500~5000°K or more. The beam from the sodium scatters irregularly, most of the beam doesn't shine on the ground.

And we must admit another fact that the Ra index of sodium is 20-40, very slow. Under the shining of sodium, it is very dim and we feel very dizzy. Ra of LED is as high as 75-80, under the shining of LU4, it is brght and we feel ease.

So from the actual lighting effect, LED lighting is much brighter than high power sodium.

LED lighting of 100W can replace the high power sodium of 250W or halogen of 300W. The lamp flux of 100W LED lighting is about 6000 lumens. The illumination flux is about 16 LUX on the ground with the lamp pole 12 meters high. For the high power sodium of 250W, it can give out 20,000 lumens, but on the ground it is about 7,000 lumens. its illumination flux on the ground is 30-40 lux. Because of the difference of Ra index, here are illumination flux amendment index for LED lighting and sodium. For LEDs, it is 2.35 times and for sodiums, it is 0.94 times. So after amending, under the shining of LED lamp, it is 37.6 lux. For the sodium, it is 28.2 -37.6 lux.

That why we say LED street light can properly replace the high power sodiums.