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Friday Night Lights: Great Light is About More Than Lumens Per Watt
Usually Friday Night Lights is the latest news from our manufacturers, this week I hope you’ll allow me a little rant.
In meetings over the last couple of weeks, evaluation of LED fixtures has come up often. One point that comes up over and over is the idea that LED fixtures should generate at least 100 LPW. Go to a trade show and watch as different manufacturers brag, “These strips generate over 130 lumens per watt!” Then you look at the strip and your retinas burn a little you shut your eyes and vapor trails of red and blue are left behind. That light was surely efficient at blinding you. Evaluating a light source is about much more than the sheer lumens per watt metric.
There’s a lot more to a source of light that the simple lumens per watt calculation. Like what?
Does it send light where I want it to?
Does the color temperature and color quality work for my application?
Is the light comfortable for the task it’s supposed to accomplish?
When you start to delve into those questions, you’ll start to find that when it comes to how people actually live with light there are metrics way more important than lumens per watt.
Case in point, glare. Glare is difficult to quantify. There’s no glare score on a cut sheet (though, perhaps there should be), glare is best observed in person. In fact, you can only really discern how much glare a given fixture will create but looking at it in its proper installed orientation. LEDs are more prone to glare because they are a collection of point sources. When not properly shielded, these sources create exceptional glare. Let me ask, what’s the point of investing in a lighting fixture that saves energy through efficacy if it is too uncomfortable to actually sit under?
The same can be said for color consistency. When all we focus on is sheer light for watts we forget to think about color quality and consistency. What happens when you’ve retrofitted a room full of troffers and one end of the room is a pinkish 3000K and the other is a yellowish 3000K? Is sheer efficacy worth losing visual comfort and acuity?
Now I can hear some readers crying out, “but in a service hallway (parking lot/stairwell/elevator cab) who cares?”
Maybe there are some applications where raw efficacy is all that’s required. But that’s the answer of someone who doesn’t truly care about light. Folks that work in service hallways deserve glare free illumination. Your client’s parking garage deserves even, glare-free illumination. The library deserves consistent color. Great lighting manufacturers balance all of these factors when bringing a product to the market. Anyone can bring a bright efficacious fixture to market, but is it a fixture you actually want to live with?