The Truth About Lumens: Uncovered

Why is it you can replace some lights with more ‘advertised’ lumens with a LED light with less lumens. Here are 4 reasons:

1. Focused Lumens:

LED light is directional, conventional light sources are omnidirectional and require reflectors to gather the light and focus it to where it is needed. Any reflection that is over 1 bounce effectively loses the effect of the lumen. It has been proven that you can lose up to 30% of the effective lumens in this process.

2. Quality of Lumens:
This is related to CRI, and the best explanation is seeing how much better you can see when comparing LED to High Pressure Sodium. It is not uncommon to have customers tell you that 20,000 lumens of LED appear brighter than 60,000 lumens of HPS. The basic truth is you need less quantity when you have higher quality.

3. Photopic and Scotopic Lumens:
This has to do with how a camera perceives lumens and how humans perceive lumens. Photopic lumens are lumens that are detected by a device that is similar to a camera. Light meters register photopic lumens.  Scotopic lumens are lumens detected by the human eye. LED produces light within these spectrum’s, which means the light perceived by LED is light that we use. It is rare to see a LED light produce IP or UV spectrums. These wavelengths are invisible to people, so they have no value to us from a vision perspective.

The science of scotopic lumens is associated with a factor that allows us to adjust the photopic value to give a true representation of how useful the lumens are. The factor, developed by scientists, is an attempt to level the playing field. The factor is used to adjust the effective value of the lumen, either up or down from the advertised photopic lumen advertised on the package. Some lights, like HPS, have a factor that reduces the lumen amount. LED, on the other hand, typically has a factor > 1.7, which means the lumens it is producing is far more effective to us. Therefore, less lumens is required to do the job.

4. Lumen Degradation:
It is not uncommon for HID bulbs to have lost up to 50% of its initial lumens after only 5000 hours of life. Yet these bulbs are rated for 20000 hours. That means the customer is using a bulb that is performing poorly for the next 15000 hours of life. As well, as lumens degrade, so does CRI. And so the “effective lumens” of the light is dropping quickly.

We have been very successful replacing 400W Metal Halide bulbs with our 105W LED Retrofit Kit. The comments we here back is the light is brighter and the area is brighter. It currently produces 15,776 lumens. Another example is our 18W LED tube, producing 1900 lumens, compared to a 32W 4 ft fluorescent tube, producing close to 2900 lumens. The main reason is all our lumens are coming straight down, where as only a small portion of the fluorescent tube is coming down and the majority of the light is requiring  a reflector to gather it and shine it downwards. After many projects, our customers tell us that it is brighter and feels better than working underneath fluorescent lighting