Designing Beyond Fidelity

I recently began a project that includes about 8,000 SF of office space that is completely without windows or skylights.  I’ve renovated spaces like this before, and the common complaint from occupants was a disconnect from daylight, weather, and the way they indicate the passage of time.  On this project, I determined that the most appropriate solution was to use a light source that rendered colors in a way that is highly preferred to make the spaces more pleasant to occupy and use.

Of course, as a designer who is very knowledgable about color rendering issues and is a TM-30 advocate, I know two things.  First, highly preferred is not high fidelity.  People prefer a light source that slightly increases the saturation of object colors (especially reds) over a high fidelity source.  Second, TM-30’s Annex E provides specifiers with ranges for certain TM-30 measurements that allow us to accurately specify highly preferred light sources.

The task seemed simple enough.  Forget about fidelity and find a fixture/LED combination with a spectrum designed for preference, i.e. a light source that meets the TM-30 Annex E specification for a highly preferred (aka P1) light source.  After all, we’ve had TM-30 for seven years now, and Annex E for four years.  Surely, by now LED manufacturers have introduced products that meet color rendering goals other than fidelity, right?  Who wouldn’t see that as a huge marketing opportunity?  And surely fixture manufacturers would offer specifiers that LED, again to differentiate their products from the many, many, many similar products from other manufacturers…right?

Alas, the answer is, “No.”  One member of the IES Color Committee shared with me a database of over 1,000 LED products, their SPDs, and their various TM-30 measurements, including the Annex E Preference Design Intent.  Of those, there are a generous handful of retrofit lamps, most of them by Soraa and Cree, that meet the P1 specification, but only one LED in commercially available linear LED fixtures – Focal Point’s Preferred Light series.  That’s it!

Fortunately, this project is for a private firm so I don’t have to worry about developing a three-name or performance spec.  Otherwise, I would have to give up on a preferred spectrum and default to high fidelity not because it would be appropriate for the project but simply because there are more options.

I’ve mentioned fidelity and preference.  You might be asking if there are other color rendering goals.  The answer is, “Yes.”  Other color rendering design goals, with brief explanations, include:

Preference.  Light distorts object colors with slight increases in saturation, especially reds, in a way that is preferred over the reference light source (that is, preferred over high fidelity).   This might be the goal in an expensive restaurant where you want to emphasize the beautiful colors of the food, people, and interior design.

Vividness.  Light renders object colors as more or less vivid, or saturated, than the reference light source. Vividness is different from Preference in the degree of distorted saturation and the design intent – making colors pop, not making colors more attractive.  This might be the goal in the Skittles store in Times Square where you want the colors to leap out at people.  

Naturalness. Light renders object colors as expected, which, surprisingly, is usually not the same as fidelity.  This might be the color rendering goal in a grocery store where you want the food to look ripe and appetizing.

Discrimination.  Light renders object colors so they can be appropriately sorted. This might be the goal in a facility where even slight color variations must be detected.

Specifiers are captives of manufacturers.  We can have design goals oriented toward the needs of the users and the success of the project, but manufacturers only want to sell us fidelity, the same way they’ve been selling us fidelity since CRI was introduced in 1965.  For 50 years we only had a hammer (CRI) so all problems were nails (fidelity).  TM-30 changed that and it’s time for manufacturers to catch up.

Where are the Photometrics?

Today I want to talk about the lack of photometric information provided by manufacturers because the presentation of information frustrates me in two ways. The first issue is the lack of information provided. The second is the difficulty of finding real world examples of what I teach in class. What’s the value of knowing the point and lumen methods if the information needed isn’t available? It seems to be a problem that’s getting worse and I’m not sure why.

  • Do manufacturers not understand photometric calculations, so they don’t see the value in including them?
  • Do manufacturers think lighting designers don’t understand photometrics, so they don’t bother including them?
  • Do manufactures not understand how lighting designers work, and think all calculations are done in AGI? I suspect this is the answer.

By failing to publish photometrics, manufacturers are dictating my workflow without understanding how I work and why I work the way I do. I rarely name names, but I’m going to make an exception here. Maybe a little photmetric-shaming (one of the most obscure types of shaming, to be sure!) will get manufacturers to change.

Are You a Contender?

When I navigate my way to a fixture web page and open the cut sheet my main goal is to determine if the fixture is a contender. Does it seem to have the features I’m looking for? If not I can move on. If so, the next question is, “Does it have the performance I’m looking for?” Photometrically, I’m looking for general distribution type, followed by more specific distribution information, lumen output and load, and beam angle. If those look good, I’ll scroll down the cut sheet to the photometric section to get some info to run a quick calculation in a spreadsheet that’s open on my desktop. If the fixture works in that quick calculation I’ll download the cut sheet and .ies file and run an AGI calc when I’m ready. What I’m looking for on the cut sheet, depending not the calculation, is:

  • Lumen output
  • Center beam candlepower
  • Beam angle
  • Candelas distribution
  • Coefficient of utilization (CU) table

For example, I recently went looking for a linear downlight. My first stop was Coronet because I know they’ve recently revamped their historically deficient cut sheets. Are the new cut sheets any better? No. The first page of the cut sheet for the LSR2, for example, now has a section labeled “Optics” (not photometrics) and gives a sort of candlepower distribution curve, but there’s only one number, which seems to be candlepower at nadir but isn’t labeled as such. A separate section at the bottom of the next page shows “Performance” in terms of watts/ft and lumens/ft for three output levels. That’s it. Any reasonable calculation of the fixture’s performance in a space requires downloading .ies files, building a model in AGI, and running a calculation. As I said earlier, that’s not my workflow. I can run a lumen method calc much faster than I can build an AGI calc and I don’t want to be forced into AGI.

Next I looked at Focal Point’s Seem 2. As with Coronet, there’s a candlepower distribution curve. The ordering matrix tells me there are four lumen outputs, and there’s a table of output, watts, and lumens/watt. A lot of page space is given to lengths and controls, but there’s nothing else about photometric performance on the cut sheet. To find any useful information I have to download .ies files and open them in Photometric Toolbox or AGI.

Finally, I looked at Acuity’s Mark Lighting. The cut sheet for the Slot 2 LED presents a table of lumens/ft, watts/ft, and lumens/watt for four output levels, but there’s no candlepower distribution curve or CU table. On the plus side, the information I want is provided, but in a separate location on the web page called Photometry & Revit (BIM). If I click on Report I find a polar candelas graph, zonal lumen summary, CU table, etc. I wish this was in the cut sheet, but at least it’s available.

I have similar complaints about other manufacturers who make fixtures I generally like: Alphabet, USAI, Day-O-Lite, and Ecosense among them.

Let Manufacturers Know

If you’re similarly frustrated let manufacturers know. If you’re at Lightair this week tell them face to face. If not, tell your reps and anyone at the factory you may know.

Standard 189.1 Now Includes TM-30 Requirements

Yesterday an addendum to ANSI/ASHRAE/ICC/USGBC/IES Standard 189.1-2017 Standard for the Design of High-Performance Green Buildings was published. The addendum makes changes to Section 8.3.5, which covers lighting. One of the biggest changes is to add TM-30 color rendition criteria to the section on Indoor Lighting Quality. Here’s the relevant text: Color Rendition. At least 95% of lighting power of nominally white lighting within each enclosed space shall be provided by luminaires that meet the following criteria at full light output in accordance with IES-TM-30, Annex E, P2 and F3:
1. Rf of at least 85
2. Rf,h1 of at least 85
3. Rg of at least 92
4. Rcs,h1 of at least -7% but no greater than +19%

Nominally white lighting is lighting that has chromaticity within the basic or extended nominal color correlated temperature (CCT) specifications of ANSI C78.377.

Where a lighting system is capable of changing its spectrum, it shall be capable of meeting the color rendition requirements within each nominal CCT of 2700 K, 3500 K, 4000 K, and 5000 K, as defined in ANSI C78.377, that the system is capable of delivering.

I hope that this is going to put more pressure on manufacturers to improve the color rendering of their luminaires as measured by TM-30, not CRI, and to provide TM-30 information on their cut sheets. If not, they’ll risk not being considered on projects that have TM-30 requirements.

CIE Position Statement on the use of UV-C

As interest in using light disinfection continues to grow standard setting organizations and manufacturers are becoming more active in this area.  The International Commission on Illumination (CIE) has just released a position statement on the use of ultraviolet radiation to manage the risk of COVID-19 transmission.

Here are a few bullet points:

  • While ultraviolet light ranges from 400 nm to 100 nm, the most effective wavelengths are at around 254 nm and this is generally what is meant by germicidal ultraviolet or GUV.
  • UV-C has been successfully used for water disinfection and in air handling units for many years.  UV-C has also seen a resurgence for use in healthcare environments.
  • Direct exposure to UV-C can cause photokeratitis (similar to snow blindness) and erythema (skin reddening similar to sunburn) so carefully shielded luminaires are required when used in occupied spaces.
  • Consumers should be wary of products not approved by consumer safety organizations.  Such products could be hazardous to use or may not emit UV-C at all.

Read the full position statement.

Tariffs Impact Lighting Costs

We have been hearing from contractors that many fixture manufacturers, including Acuity Brands, Hubbell Lighting and Eaton, are being forced to raise prices because of the recent tariff increase on Chinese goods.  

The tariff on lighting components and fixtures was 10%.  However, on May 10th the tariff was raised to 25%.  The 15% tariff increase is too much for manufacturers to absorb so they, and ECs, consider this a Force Majeure event (unforeseeable circumstances that prevent someone from fulfilling a contract).  By invoking Force Majeure they are voiding previous pricing and are issuing new quotes showing the cost increases.  

This doesn’t mean that all fixture prices are going to increase by 15%.  The amount of Chinese made components varies by manufacturer and fixture line.  More Chinese components will mean a higher cost increase.  To us this means that until the tariff and trade situation with China settles down lighting designers would do well to keep their clients informed of the varying impact on fixture costs and therefore fixture budgets.

Focal Point Introduces TM-30 Based “Preferred Light”

Today Focal Point Lights of Chicago, IL introduced a series of fixtures that feature what they call Preferred Light.  Preferred Light is based on recent studies at PNNL and Penn State, plus their own study, and uses TM-30’s Rf, Rg, and Hue Bin 16 values to establish a balance of fidelity, saturation, and red rendering that is “visually appealing to humans.”

The overall idea is that people seem to prefer a light source that slightly over saturated most colors, especially red.  “Using a custom LED mix, Focal Point defines Preferred Light using TM-30-15 metrics as having a fidelity (Rf) of 89, a gamut (Rg) of 107, and over-saturating Hue Bin 16, deep red content, by 9% at a [Correlated] Color Temperature of 3500K.”  So, by using the statistical measures of TM-30 and applying them to the related topic of color preference Focal Point has identified an optimized set of LED products to meet their customers’ needs.

I’ll be the first to admit that it may be risky to base all of this on only three studies, but other studies have shown that the TM-30 results can be applied in this way, and are also showing us the relative importance of the various calculated values.  I’m excited to see the industry using the tools, and am looking forward to seeing the Preferred Light for myself.

IoT Lighting? No Thanks.

The current global cyber-attack, combined with last year’s “denial of service attack has me thinking about the lighting industry and IoT.

It was ironic that last year’s attack happened just days before the IES annual conference, at which IoT lighting was touted as the next big thing that everyone had to adopt or be left behind. You may recall that one aspect of that attack was that hackers recruited IoT devices like thermostats and smoke detectors. Many designers may think, “Well, sure, homeowners don’t have good security, but that wouldn’t happen to one of my corporate clients.” The current attack shows the flaw in that thinking. New tools have allowed hackers access to supposedly secure networks, and not all networks that should be secure (such as Britain’s NHS) actually are.

The question, then, is, “Why should my lighting system use IoT?” I’ve asked several friends in lighting design firms large and small and the answers I’ve received are revealing. Almost no one has a client who is asking for this. (I’ve had exactly one client who wanted the lighting system connected to the corporate LAN.) Do they want lighting systems connected to their BMS? If the client is knowledgeable and the building is large, yes, although today’s lighting systems have so many programming options we don’t need the BMS to control the lighting system. Do they want lighting systems to use Wi-Fi so that users can adjust the lights from phones and pads? Not very often. “Why would I want to give that many people authorization to change the lighting?” is the question asked, and rightly so. Do they want light fixtures with IP addresses and built-in Wi-Fi, Li-Fi, daylight sensors, occupancy sensors, temperature sensors, humidity sensors, and software that tracks shoppers or monitors space usage? “How much will that cost?” is the usual first question, followed by a strong “No.”

If we designers don’t see an artistic or operational advantage to these systems, and if our clients don’t see an advantage and aren’t asking for these systems, why all the noise about them? The answer, of course, isn’t better lighting design or increased energy efficiency, it’s money. Companies like Cisco see expanded profits from embedding Cisco sensors in every light fixture in a building, connecting all of those fixtures to Cisco POE switches and perhaps controlling the fixtures and sensors with Cisco software. Fixture manufacturers, always looking for a way to differentiate their products, jump on board. Marketing departments create hype, magazines and web sites need material, and voila! the next “must have” lighting system feature.

Who’s providing network security? The corporate IT department, I guess. Are the lighting systems vulnerable to hacking? The current and recent attacks tell us the answer is, “Yes.” Are manufacturers of IoT devices investing in security? Not really. They see it as the responsibility of someone upstream. Would anyone want a lighting system that is vulnerable to being turned off in an emergency, or reprogrammed by someone just to see if they can do it? No.

Some of the lighting systems I am designing are quite complex involving hundreds of fixtures with hundreds of addresses, multiple control protocols, and multiple points of control including touchscreens and Wi-Fi devices. One thing no one has to worry about, though, is high-jacking or corruption of the system. Each system stands alone. Software updates, if they are ever needed, are downloaded and installed via a USB key. Anyone wanting access to the system has to be within Wi-Fi range and has to hack the network. What would they get? Access to a single lighting system. There’s almost no reward and therefore there’s almost no incentive. Call me a Luddite if you like, but for now I’m going to stick to designing secure, flexible systems that provide my clients with only the features that they want at a price they are willing to pay. I’m sure that the pressure to “innovate” will eventually lead me to using these IoT systems. But for security’s sake I’m going to resist for as long as I can.

With LEDs, Knowledge is Power

I’ve been hired to review an architect’s lighting design and then design an appropriate control system. The fixtures selected are all LED products by a manufacturer that falls into the high-end residential/economy commercial range of quality and price. The cut sheets are extremely frustrating. After nearly a decade of LED lighting, and with all of the progress the industry has made in setting standards so that designers and specifiers know what they’re getting, this manufacturer still tells us nothing. What basic information is missing?

 Lamp life. The only information even remotely connected to lamp life is the statement that the fixture is covered under a five-year warranty. There’s nothing else. Not a word. How much light, compared to initial output, can we expect at that five-year mark?  We have no idea.

LEDs do not fail like other lamps do.  They gradually dim as they age.  At what point is the light output so low that we’d say the lamp is no longer useful?  Right now the answer is when the light output has fallen to 70% of the initial output (often referred to as L70), although many designers prefer to use 80% of initial output (referred to as L80).  This is calculated using a procedure developed by the IES and designated as LM-80 (details are here and here).  What we want, at a minimum, is the IES LM-80 calculation of lamp life to 70% of initial output. L80 data would be even better.

 Warranty. The warranty is not on the manufacturer’s web site so, although we’re told that it is good for five years, we have no information about what is covered and what is excluded.

 LED manufacturer. With all other lamp types the designer chooses the exact lamp for the project. Criteria such as initial lumen output, mean lumen output, lamp life, color temperature, CRI, and the manufacturer’s reputation for quality are all valid considerations. We have standards that allow designers to make valid comparisons between LED products, too, but we can do that only if that information is generated and shared. I suspect that this fixture manufacturer uses LEDs from a several manufacturers based on the best price available, and that the performance of those LEDs varies widely.

 Color consistency. The cut sheet says that the standard applied to their LED selection is, “minimum 3-step color binning.” We are left to infer that means three-step MacAdam Ellipses.  A one-step MacAdam Ellipse describes a region on a chromaticity diagram or color space where the edges of the ellipse represent a just noticeable difference from the color at the center (additional information on MacAdam Ellipses is here and here).  The data is usually plotted on the CIE 1931 (x, y) chromaticity diagram.  The diagram below shows 10-step MacAdam Ellipses.

"CIExy1931 MacAdam". Licensed under CC BY-SA 3.0 via Wikimedia Commons -
“CIExy1931 MacAdam”. Licensed under CC BY-SA 3.0 via Wikimedia Commons –


The color variation within a three-step ellipse would be noticeable to over 99% of the population.  Worse, though, is that a three-step ellipse is the minimum, not the maximum. Knowing this, the designer should have no expectation of color consistency from one fixture to another.

 Photometrics. The cut sheet contains no information about the optical performance of the fixture. IES files are available, but it’s very difficult to look at the array of numbers and understand performance, which is why the good manufacturers include photometric information on their documentation, including candlepower distribution curves and CU tables.

Part of my review will be pointing out the lack of data about the specified fixtures and recommending several alternates by manufacturers who provide the information necessary to evaluate their products.

Student Custom Fixtures

The main design assignment for this  semester’s Pratt students is a cafe.  The students selected their own interior design and had to develop a custom lighting fixture that is integrated with that design.  Here area few of this semester’s  fixtures.

Lauren Mercuri
Lauren Mercuri

Tammy Zhao
Tammy Zhao

Pradthana Likitplig
Pradthana Likitplig

Sol Ok
Sol Ok

Sofia Martinez
Sofia Martinez