Lighting systems are advancing at a rapid pace. New technologies are reducing energy usage, while also making lighting more efficient. To help you understand what lumens are, and how lumen intensity is measured, we have included the terms and definitions in this article.

It doesn’t matter what type of lighting you use; its intensity diminishes over time and becomes less efficient. The initial lumen intensity is at its highest when you first turn the light on. Measuring the initial lumens varies depending on the type of light.
LED luminous intensity is measured after the diodes stabilize, around 45 minutes after turning the fixture on. HID lights take longer to measure, around 1,000 hours of use, and are referred to as a burn-in.

Lumen maintenance refers to the lifespan of the fixture or lamp. In theory, LED lights will function as long as there’s an electrical current, but the lumen intensity will gradually become dim. It’s the loss of light intensity that makes the fixture or lamp obsolete.
LED lighting products are known by technical numbers, L90, L70, and L50, which are used to calculate the LED’s lifespan. The calculations are in hourly increments and estimate the amount of light the diodes are producing when the lamp spreads 90% (L90), 70% (L70), or 50% (L50) of the initial lumen intensity.
With a 70% loss of lumen intensity, the eye will detect the lower light intensity, but it only becomes a problem when the lumens decline to 30%. So, a light fixture with 72,000-hour lumen maintenance will start decreasing in intensity after being in use for 72,000 hours. It does not mean the fixture will no longer function only the light isn’t as bright.
These graphs will help further explain LED Lumen Maintenance.

Absolute Lumens

Absolute or delivered lumens is the lumens flux the lighting system generates when you are factoring in the optical loss factor. It’s a handy term to understand when you are comparing HID vs LED lamps.

When you are using HID lamps, only the intensity of the light is measured. Optical loss is not a factor with these lighting products. With HID, you only pay attention to the delivered lumens.
LEDs are a little different. Optical loss is a factor since you are testing the luminaire. The term absolute lumens is used when you are measuring its intensity.
Comparing HID vs LED lumens output accounts for multiple factors. These include the lighting product’s lifespan, lumen maintenance, and optical loss. Remember, you only account for optical loss with HID fixtures. Simply put, the flux of the installed HID light is measured to learn its efficiency. It allows you to compare the delivered lumens for each lighting technology.
Contact us for more information on which LED lighting products are best suited for your application, and to learn more about lighting comparisons. Contact Action Services Group today by calling 610-558-9773, email [email protected] , or schedule a call that fits your needs by clicking the button below.