Understanding the Importance of Delivered Lumens and Foot Candles

by | Nov 2, 2017 | 0 comments |

If you’re considering an LED retrofit your focus should be on delivered lumens and foot-candles to increase lighting performance. Lumen count may seem to be the metric for measuring a potential lighting product – but it shouldn’t be. A high quantity of lumens does not necessarily equate to brighter lighting. There are several other key factors that impact the lighting performance for your project. Let’s first understand what lumens are: Lumens are the overall light output that is produced for that product. For example, fluorescent light is omni-direction light and not all the light will be illuminating a space. Some of the light will travel upward and/or sideways. So, lumens are not the real metric that will tell you how bright your space will be. If your looking for improving your light performance delivered lumens to the surface is your key indicator. Here are some key metrics that will affect the brightness of your space:

  1. Candelas: Candela is the unit of luminous intensity of a light source. It’s a metric for the intensity of the light that is generate by the lamp
  2. Footcandles: Are an indirect measurement of delivered lumens. For example, if a lighting product produces 500 lumens how many of those lumens actually arrive at a specific square foot. The results are footcandles.
  3. Illuminance: This is light arriving at a surface. One lumen per square foot equals one foot-candle
  4. Correlated color temperature (CCT): Is a gauge of the color of the light. How yellow or blue the light appears. It’s measured in Kelvins and usually falls in a range of 2200 and 6500 Kelvin, with the low end (2200K) being more of the red/orange/yellow coloration and above 4000K is more of a blue light
  5. Color Rendering Index (CRI): is a Measure of the light quality of a light source as compared with sunlight (which is given the maximum CRI value of 100). The closer a light-source’s CRI is to 100, the better its ability to show true colors.

So, if you’re wanting to increase your lighting performance and brighten your space don’t think about just the lumens the product produces. Understand the foot-candles the lighting will produce on the surface, the CCT to get the light color/brightness that you want and a high CRI to get the best performance for your lighting project.



If after reading this post you have additional questions reach out to us here at Action Services Group by calling 610-558-9773, email [email protected], or schedule a call that fits your needs by clicking the button below. We would be happy to put together a free, no-obligation assessment for your facility. Thanks, we look forward to hearing from you soon.


Table of Contents
  1. Terminology
  2. Conclusion

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