LQC – A Light Quality Classification System that is Understandable and Valuable

Posted: February 9, 2016 in LQC
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I propose that all pursuits of a color quality metric represented in any form of numeric value based on averages of performance over any number of color samples is wholy inadequate and a wast of time. We have been using such a system for far too long, with too many questions and related surrounding quality issues unanswered to continue with such a weak approach. I suggest that we pursue a Lighting Qualities Classification system that encompass eight (8) core variables that are critical to identification and selection of lighting products. This would be represented in a similar fashion as the successful Ingress Protection (IP) rating system already in use.

My concept is that there are three core categories of concern that lighting customers and specifiers want answers to in an easy to use and apply form. These are Uniformity, Color Quality, and for some, Human Factors. A color quality standard, as we already know, is meaningless if uniformity is not known. The current and all proposed metrics for lighting quality also fail to deliver any insight into color tonal shifts caused by Duv, and do not indicate or suggest that all sources of identical result are going to be uniform in appearance. This proposed LQC classification system addresses these issues, representing lighting product performance using data already available from current test results, in a manner that can be applied to select appropriate products for application.

Here is my first raft concept of the LQC classification in a table format, similar to that used to define the IP rating system:

LQC Rating System Table

LQC Rating System Table – Proposed Draft

In this classification system one can expect:

Uniformity Performance – Products from a range of manufacturers, or individual products from any one manufacturer, with a classification of 5 will deliver uniform appearance, while the greatest variations will occur in products with a classification of 1.

Quality Performance – Products from a range of manufacturers, or individual products from any one manufacturer, with a classification of 5 will deliver uniformly high color fidelity, minimal saturation effects, and strong color rendering over the complete spectral range, while the greatest variations and lowest color rendering results will occur in products with a classification of 1.

Human Factors Performance –  Products with a classification of 5 will deliver optimal human visual performance, while those with a classification of 1 will deliver less than optimum performance. This is an optional classification (like the thrd value in the IP rating for impact protection) recognizing that in some applications, human visual performance, either for acuity or to optimize energy use, is not a priority – such as high end hospitality where warm sources and mood/appearance are the primary drivers.

Based on this, decision makers can pre-qualify products based on application needs and requirements. Just as an IP67 rating is unnecessary for 100% of applications, an LQC555 product is not a universal requirement. Here are some examples of application of this LQC classification system:

Parking Garage Lighting – LQC124 will produce a product with minimal attention to uniformity, a good color rendering quality (for identification of color), and a high human factors performance level to optimize energy use and visibility.

Classroom – LQC445 will produce good uniformity, high color rendering performance, and strong human visual system support for learning environments at a reasonable economic level.

High End Retail or Museum – LQC55, or LQC553 will produce maximum uniformity, maximum color performance, and acceptable human factors for the application using warm color sources (optional classification).

Residential – LQC442 will produce a product that suits the majority of fussy homeowners and represents the human factors likely to be available when using warm color light sources

Critical Task and Inspection Lighting – LQC555 will produce maximum performance in uniformity, color and visual performance.

Low Activity Storage (low color demand) – LQC11, or LQC111 will support the most economical light sources and indicates a minimal need for quality over cost.

High Speed, Low Color Demand Task Application on a Budget – LQC115 might be applied,  utilizing TM-24 methods to reduce energy consumption through application of enhanced visual performance, with lowest cost products as a priority

I recognize that a classification system of this type requires more refinement. However, I suggest that this is a robust approach that with minimal understanding, manufacturers can apply this to market products toward specific intended application, while decision makers and designers can select and communicate their requirements through specification of a desired or necessary classification for the intended application.

The application of this type of multiple factors classification system encompasses the core concerns of decision makers,  answers questions not now being delivered, removes the need for decision makers to attempt to hack together evaluations based on data that is not always readily available, and builds a foundation to build products and identify latent demands that are now concealed by the virtual lack of actionable metrics for us all to work from.

Specifications could also be written around identification of a range of acceptable product classes within the three categories. For example, one might  need uniformity to remain very tight, where a specification of anb absolute “5” classification is set. However, that same specification may not require perfect quality performance beyond that, so a quality value might be represented as >2, or indicated as  range of 2-5. Meanwhile that same specification may consider energy efficiency as an important requirement, demanding a Human Factors classification of >4 or a range of 4-5 as acceptable. This opens the door to a wider range of products, from LQC524 up through LQC555 to be applied and offered by manufacturers.

Manufacturers can use this classification system to expose and promote their products performance and its comparison to competition. For example, a manufacturer that is committed to the highest uniformity in their product offerings, at the most popular quality levels, can state that all of their products deliver an LQC of 53 or better, while specific offerings targeting the human factors market space can be promoted as delivering an LQC of 534 or greater, indicating the only area of variability and performance selection is choosing a color metric that fits the application.

Just as the IP rating system is more descriptive than the UL Wet and Damp labeling standards, the LQC classification reaches beyond simplistic single aspect lighting qualities of CRIe or TM30,  that are now creating more questions than answers.

To evaluate your own product, download this Excel workbook and fill in the data and ratings, or make one of your own from this basic starting point. LQC Workbook: lqc

Comments
  1. Peter Wachter says:

    At first Kevin, I thought of suggesting that the ratings be flipped so “1” is the best. But thinking in reference to IP ratings as you had mentioned, your approach makes sense. Since we can safely assume that quality improvements are inevitable some day there may be a “6” or “7”, etc. Thanks very much for your efforts in this regard.

  2. […] within these parameters, as well as other performance categories, part of which I described in the LQC article. Beyond the basics of getting the design right for the customer, I see product selection […]

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