Category: Lighting Profession

My New Book, Fundamentals of Energy Efficient Lighting and Controls, is Now Available

Cover of Fundamentals of Energy Efficient Lighting and Controls

I’m pleased and proud to announce that my new book, Fundamentals of Energy Efficient Lighting and Controls, is available for pre-order beginning today (March 13) and will begin shipping on April 3rd.

The book grew out of conversations with the Association of Energy Engineers and their need for better study material for their Certified Lighting Efficiency Professional (CLEP) exam.  This lead to an interesting observation: there are several good books aimed at educating future lighting designers (including my own Designing with Light) and several good books aimed at educating energy efficiency professionals, but none that address energy efficiency in lighting with an eye toward maintaining quality lighting design.  That is the goal of this book.

It is a comprehensive guide to quality, energy efficient lighting design and controls for commercial and institutional spaces. The text cover topics such as light sources and light fixtures, brightness and energy use calculations, financial analysis, light fixture maintenance, and auditing existing lighting systems.

As we all know, the introduction of LEDs and the phase out of traditional light sources, along with increasingly stringent energy codes, is leading to highly efficient lighting designs. This book places quality lighting design and consideration for the comfort of the occupants on an equal footing with energy efficiency to emphasize a holistic approach. With over a hundred high quality images and illustrations, Fundamentals:

  • Provides an overview of lighting design considerations and the design process.
  • Thoroughly covers light sources and lighting fixtures with an emphasis on LEDs.
  • Explains the requirements found in most energy conservation codes and voluntary programs including lighting controls, daylighting, and limits on lighting system power consumption.
  • Discusses non-design issues such as maintenance, energy audits, and the financial analysis of retrofit vs replacement options in existing buildings.

Fundamentals of Energy Efficient Lighting and Controls is available from Amazon, Barnes & Noble, Routledge, and other online retailers.

CIE Recommends Transition from CRI to Rf

Earlier this month, CIE published CIE Position Statement on Color Quality Metrics, in which it recommends the lighting industry transition from the outdated and sometimes inaccurate General Color Rendering Index (CRI) to the General Color Fidelity Index (Rf ) defined in CIE 224:2017.  The position statement notes that problems with CRI (which we’ve known about for years) include use of an outdated color space (CIE 1960 (u, v)), the small number of samples used to calculate CRI (only 8), and that CRI has proven to be especially problematic in evaluating narrow band emitters.

The good news is that CIE is finally recommending retiring CRI from use (which was last updated over 50 years ago in 1974) and adopting a modern, accurate metric for evaluating fidelity for all lighting applications.  That’s a huge step forward for the lighting industry.

The less good news is that it stops there. The position statement acknowledges that fidelity is not the only aspect of color rendering, and that studies have shown preferences for light sources that slightly enhance saturation (and therefore reduce fidelity).  However, it makes no mention of other metrics (such as ANSI/IES TM-30’s Gamut Index and Preference Design Intent) that address the issue.  Since CIE 227’s Rf and TM-30’s Rf are identical, I see this as a belated endorsement of Rf as a fidelity metric and of TM-30 in general.  My hope is that this spurs the industry to greater adoption of TM-30, especially for its evaluation of color preference, vividness, and fidelity described in Annex E.

One side note: Rf as defined in CIE 227 is Rf as defined in TM-30.  In fact, TM-30 was published two years before CIE 227, which was a response to TM-30.  In evaluating TM-30, CIE found that there were a few places where CIE and IES chose different methods of extrapolating certain information.  Since CIE had formalized their procedures and IES had not, the two organizations worked together to harmonize their calculations into one calculation that is used in both systems.  It’s frustrating that the CIE position statement reads as if CIE developed Rf out of whole cloth, rather than as a response to TM-30 and a mutual refinement of the Rf calculation.

Retail Design Institute Lighting Summit

On Wednesday, September 25th I’ll be on a panel at the Retail Design Institute New York Chapter’s Lighting Summit 2024.  The other panelists are Shoshanna Segal of Hantranft Lighting Design, Carlotta Dove of IA Interior Architects, and Kazumi Tanimura of Atelier Lumiere.  The event is at the Illuminations showroom at 5 Penn Plaza.  Hope to see you there!

TM-30 Update: Challenges and strategies for working with SSL manufacturers – LD+A

I have written a lot about TM-30 from the specifier’s viewpoint – how TM-30 is better than CRI, explanations of the various TM-30 measures. why TM-30 data and reports are so important, how to get TM-30 data or reports, how to use TM-30, etc.

This month’s LD+A has a great article about TM-30 from the manufacturer’s viewpoint that addresses issues such as – why TM-30 reports for every LED option aren’t always available, why some manufacturers are reluctant to prepare TM-30 reports, strategies specifiers can use to deal with these issues, and more.  It’s a very useful article.  Give it a read at TM-30 Update: Challenges and strategies for working with SSL manufacturers – Illuminating Engineering Society %

AI and the Internet Need to Learn Color Rendering

Recently a colleague of mine from the IES Color Committee asked of one of the new AIs “Tell me about color rendering.”  If we assume that the answer was formulated based on information about color rendering that is available on the internet we have a problem because the answer the AI returned was almost completely wrong.  That strongly suggests that most individuals and manufacturers posting information about color rendering don’t fully understand color rendering and are perpetuating outdated or incorrect information.  Here’s what the AI had to say, and what’s wrong with it’s response.

Color rendering is a measure of how well a light source reveals the true colors of objects. (1) A light source with a high CRI (Color Rendering Index) will show objects in their natural colors (2), while a light source with a low CRI will make objects look dull or washed out (3).  The CRI is a scale from 0 to 100 (4), with 100 being the perfect score (5).  A light source with a CRI of 100 will show objects in their true colors (1) while a light source with a CRI if 0 will make all objects look the same color (6).

The CRI (7) is important for applications where it is important to see objects in their true colors (1), such as art galleries, hospitals, and retail stores (8).  It is also important for applications where it is important to see subtle variations in color such as fashion design and photography (9).

There are a few things that can affect the CRI of a light source (10).  The type of light source (incandescent, fluorescent, LED, etc.) will affect the CRI (11).  The color temperature of the light source will also affect the CRI (12).  Light sources with a higher color temperature will have a higher CRI (12).

The CRI (7) is a valuable tool for choosing the right light source for your application.  By understanding the CRI, you can choose a light source that will show your objects in their true colors (1) and help you achiever the desired look and feel for your space.

  1. Objects don’t have “true” colors, they have apparent colors.  The color of an object is determined by the spectrum of light striking it, it’s reflective properties, and the resulting light directed toward the observer.  An object’s reflective properties don’t change, but the spectrum of light changes every time the light source changes.  Changing the spectrum may, therefore, change the color appearance of the object, hence apparent color.
  2. While there is a correlation between fidelity and naturalness, they are not the same thing.  CRI measures fidelity, i.e. how well a given light source matches the color rendering of a defined reference light source.
  3. One of the problems with single measure metrics like CRI is that there’s a lot of information that isn’t conveyed.  As CRI values drop, the only thing conveyed is that the match to the reference light source is worse.  A worse match, however, doesn’t mean colors are made dull. It could be they are increased in saturation since both deviations from the reference are equally penalized.  That’s the advantage of TM-30.  As Rf decreases we can see why by looking at Rg and some of the other 147 measures.
  4. CRI can have negative values.  TM-30 Rf is calculated so that 0 is the lowest value.
  5. 100 is the highest value.  It’s dangerous to call it “perfect” though as that implies that high fidelity is the only color rendering goal, which it isn’t.  TM-30 provides information for the color rendering goals of preference and vividness, and may include more in the future.
  6. A CRI of 0 will certainly make nearly all colors look terrible and very similar, but not all the same.
  7. CRI isn’t a proper noun, and shouldn’t be preceded by “the”.
  8. There are strong arguments for emphasizing preference over fidelity in many applications, including retail.  Again, fidelity isn’t the only color rendering goal, although it is the only one CRI measures.
  9. Research shows that high fidelity isn’t necessarily the best spectrum for detecting color difference.  Additional research is needed, but the IES may eventually add a color difference metric to TM-30.
  10. Only one thing affects CRI value – the spectrum of the light source.
  11. This is true because different light producing technologies have similar quirks in their spectra.  Those similarities can lead us to blanket statements such as “all fluorescents are green” which are not true for all products.  Again, the individual light source’s spectrum determines everything.
  12. A common misconception, but not true at all.  Not in the slightest. CCT and CRI are separate metrics.

CCT Doesn’t Predict Circadian Impact

Two of my IES Color Committee friends and colleagues, Tony Esposito and Kevin Houser, have just published a paper in Scientific Reports that looks at the common assumption that CCT can be used to assess circadian entrainment and other biological impacts of light. The assumption by many is that high CCT light contains the blue wavelengths necessary for circadian entrainment, and that assumption is emphasized in the marketing a wide range of tunable white fixtures.

Their study used a five-channel LED system in a full scale model of a room. The LEDs were used to create over 200,000 SPDs across a range of color temperatures and illuminance levels. They found that CCT alone is not an accurate predictor of the spectral content of the light. Since the three major systems used to predict “biological potency” of light – CIE melanopic Equivalent Daylight Illuminance (mel-EDI), Equivalent Melanopic Lux (EML), and Circadian Stimulus (CS) – all use spectral analysis to understand biological impact, using CCT alone is simply inadequate. High CCT may correspond to circadian response, or it may not. They conclude their paper by saying

The lighting industry is experiencing rapid transformation as we expand our awareness of the non-visual impacts of light on humans. It is pertinent that we develop measures, methods, and strategies for implementing architectural lighting solutions that support these non-visual impacts. To do so, we need accurate and predictive measures of the biological potency of light that are based on sound science. In this study, we have argued that CCT is conceptually inappropriate for this purpose and performed a numerical analysis demonstrating that significant variation in circadian stimulus and melanopic equivalent daylight illuminance exists at any fixed CCT and photopic illuminance, making CCT an inappropriate proxy of those measures. Using CCT as a proxy for the biological potency of light cannot be justified.

Understanding that CCT doesn’t correspond with biological impact, it becomes important that designers understand the three systems and push manufacturers to begin providing the relevant information.

California Bans Fluorescent Lamps

Last week California joined Vermont and the European Union in enacting a ban on fluorescent lamps.  The California ban covers:

  • Screw or bayonet base CFLs beginning January 1, 2024
  • Pin-based CFLs beginning January 1, 2025
  • Linear fluorescent lamps (aka fluorescent tubes) beginning January 1, 2025

The ban isn’t complete because there are some specialty fluorescents that are not included, such as those used for copiers and scanners, disinfection, sunlamps for tanning, and specialized lamps for medical purposes.  However, it does apply to:

  • CFLs of all tube diameters and all tube lengths, including PL, spiral, twin tube, triple tube, 2D, U-bend, and circular
  • Linear fluorescents including:
    • single-pin, two-pin, and recessed double contact
    • all tube diameters, including T5, T8, T10, and T12
    • all tube lengths from 6″ to 8′
    • all lamp shapes, including U-bend and circular

Over the next few years hundreds of thousands, probably millions, of fixtures will need to be replaced or, if possible, converted with LED retrofit lamps.  From the perspective of efficiency and quality of light replacement is certainly preferred, but it won’t be cheap.  It’s not clear if California or utilities will offer any sort of financing to make the change.

You can download the law here.

ArchLIGHT Summit and Get A Grip On Lighting

Next month I’ll be at ArchLIGHT Summit in Dallas.  Together with my IES Color Committee co-chair Tony Esposito, we’ll be giving several presentations on how designers can make better use of TM-30 by integrating it into their workflow.  In anticipation of our ArchLIGHT Summit presentation we were interviewed on Get A Grip On Lighting, where we talked about TM-30, color perception, and color rendering, among other things.  You can watch the interview on their web site, or below.

 

Don’t Call Me A “Creative”

I was recently referred to as a “creative” and the person who said it was surprised when I asked not to be called that.  Here’s why I hate that word used as a noun.

In other industries the training, talent, and roll of individuals is recognized.  In finance, for example, there are bank tellers, stock brokers, analysts, hedge fund managers, etc.  While we might say they all work in the financial industry, we don’t call them “financials” or “moneys”.  We describe each person’s role using the name of their distinct profession.  Kayla is a financial analyst, not a “money”.

Likewise, in medicine there are nurses, doctors, surgeons, EMTs, etc.  We might collect all of their expertise when we refer to the medical or health care field, but we don’t call the individuals “medicals”.  Again, we describe each person’s distinct role or profession.  Alex is a registered nurse, not a “health”.

I work in a creative profession, but I’m a lighting designer not a “creative”.  I’m not a poet, choreographer, photographer, or web site designer.  I find it lazy and dismissive to lump all of us into one category and call us “creatives” as though we’re interchangeable, without regard to the education and skills of our very distinct professions.  You don’t want a web site designer lighting your building, or a choreographer making your web site.  To me, calling us all “creatives” disregards and degrades our unique abilities and contributions, essentially saying that what we do isn’t worth recognizing or naming.