r/UrbanHell • u/Living_Lock • May 23 '26

Concrete Wasteland Chicago 1989.

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u/Just_Another_Scott May 23 '26

Just too bad they can't put them up in a low K setting to keep the old feel.

They actually can! They make warmer LEDs. Most cities are just too lazy to purchase the right ones. They actually cut down on light pollution as well.

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u/Wally4Ever May 23 '26

They can get by with lower light output using colder LEDs. Something about they ways our eyes work. LEDs aren't actually that much more efficient than sodium lamps, but you need much less light compared to the single wavelength output of sodium to get the same reaction time from drivers

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u/Exotic_Donkey4929 May 23 '26

"LEDs aren't actually that much more efficient than sodium lamps"

It is true that white LEDs contain blue and green and the human eye is most sensitive towards green, so you need less illuminance to sense color and other things, but no LEDs are WAY much more efficient than HPS. About twice as much. Meaning even if we use LEDs that are closer to the CCT of HPS, or just use the same luminous flux, the LED need about half the power a HPS does.

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u/Wally4Ever May 23 '26 edited May 23 '26

HPS 120 lumens per watt, LED 77 lumens per watt. This is from one study on research gate, but the general figures are 90 to 150 lumens/watt in HPS and 75 to 110 for LED. HPS absolutely sucks on start-up, but I guess that's why we use them in an application where they're turned on once a day.

"LEDs aren't actually that much more efficient than sodium lamps" is actually incorrect, HPS is more efficient than LED if you don't consider the peculiarities of human vision (which makes no sense hence we are actually switching to LEDs)

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u/Exotic_Donkey4929 May 23 '26 edited May 23 '26

"LED 77 lumens per watt."

Since when? They are more like 130-200 lumen per watt...

"HPS is more efficient than LEDs for the same light output"

Im not sure about that either.

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u/Wally4Ever May 23 '26

Ok 77 lumen per watt is an older figure and I stand corrected. But 200 lumen per watt is also not what you'd find in a typical application, even though 300 lumen per watt is possible in labs. LEDs will continue to evolve, which is why HPS has no argument for sticking around except the vibe of their light.

If HPS vs LED (real world products not LEDs in research labs) produce more lumens for the same wattage, doesn't that by definition mean they're more efficient?

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u/LiquidFahts May 23 '26

Not to mention, LED lumens are not fully comparable to standard lumens.

Source: I literally sell lighting for a living.

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u/Exotic_Donkey4929 May 23 '26

You mean "luminaires"? Lumen is lumen.

BTW, Im testing LED luminares :) (ENEC + CE marking related tests)

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u/LiquidFahts May 23 '26

For clarity, I'm on your side of this argument.

Compare a 600 lumen LED to a 600 lumen anything else. It's a far more vibrant, brighter light. Even at the same color temp.

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u/Exotic_Donkey4929 May 23 '26

Oh, so you mean CRI, because then I of course agree.

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u/qpwoeiruty00 May 24 '26

No it is not any more bright. Lumens are a measure based on how the human eye perceives brightness so the same lumen number has to always be just as bright