Avoiding Bad Display Lighting

Last week I was in Boston and wanted to visit the USS Constitution. The ship was closed but the visitors center was open. When I went inside and tried to read the exhibit signage, here’s what I saw:

Track lights were positioned right over the semi-gloss signs, creating terrible reflected glare. The thing is, this is so easy to avoid. In fact, someone almost has to try to create lighting this bad. Here’s how to avoid it.

  1. Determine the location of the viewer.
  2. Determine the viewing angle.
  3. Determine the mirror angle.
  4. Place lights in the concealment zone.

IES Releases Ready Reference App

For many years the IES Ready Reference was on the desk of every lighting designer, and we were all baffled when they stopped publishing it.  Great news, it’s back!  This time as an app for your phone or tablet that’s available in the Apple App Store and Google Play.  According to the IES, the app provides:  

  • Core lighting knowledge, including values from illuminance tables
  • General knowledge information, assembled from The Lighting Handbook, 10th Edition and IES standards
  • Simple calculators for quick and easy basic lighting and energy and economic calculations
  • A search feature allowing you to find the information you want

Download it from the Apple App Store or Google Play.








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.








Design Guide for Color and Illumination

As the co-chair of the IES Color Committee I am delighted (pun intended) to announce the publication of the Design Guide for Color and Illumination.  The guide is the result of over five years of work by more than a dozen researchers, engineers, manufacturers, and designers from across the globe.  Here’s part of the description on the IES site.

Color can be described using concrete values such as chromaticity coordinates, spectral power distribution, or others discussed later in this guide. However, one’s response to color can be much more personal and emotional—and therefore more difficult to quantify. This guide takes the reader from basic vision and color vocabulary, through methods of measuring and quantifying color, and culminates in the practical use of commercially available white light and colored lights. The definitions, metrics, and references discussed will assist in building a critical understanding of the use and application of color in lighting.

It is probably the best, most thorough discussion of light and color available today.  Everyone interested in color, color perception, color rendering, and their relationship to light should read it.  It will be available at the IES booth at Lightfair.








How Bright Are Colored LEDs?

Measuring and describing the brightness of colored LEDs is an increasingly important part of a lighting designer’s practice. They are used more often, and in more types of projects, than ever before. Yet, we don’t have an accurate method for understanding exactly how much light is being produced and how bright it will appear. It’s a problem that the lighting industry needs to solve, and soon.

The human eye does not respond to all wavelengths of light equally. We have the greatest response to the yellow-green light of 555 nm. Our response falls off considerably in both directions.  That is, wavelengths of light do not contribute equally to our perception of brightness. The sensitivity curve of the human eye is called V(λ) (pronounced vee lambda) and is shown below.

The definition of a lumen, the measurement of brightness of a light source, is weighted using V(λ) and essentially assumes that the light source emits light across the visible spectrum – in other words, it produces a version of white light.

Light meters are calibrated to measure white light using V(λ) so that their measurement of brightness corresponds with our perception. Individual colored LEDs emit only a fraction of the visible spectrum, as shown below in the graph of V(λ) and the SPD of a red LED, and that’s the problem.

V(λ) and the SPD of a red LED.

Light meters measure the light that the colored LEDs provide, of course, and this information is included on an LED fixture manufacturer’s cut sheets, but it often makes no sense. For example, an RGBW fixture I’ve arbitrarily selected reports the following output in lumens: Red 388, Green 1,039, Blue 85, White 1,498. Since brightness is additive, the output when all LEDs are at full should be 3,010 lumens. However the Full RGBW output is given as 2,805 lumens! That’s 7% lower than what we expect.

The essential problem is that the colored LEDs give the light meter only a fraction of the spectrum it’s designed to measure. The meter provides a result based on its programming and calibration, but the results are often nonsensical or at odds with our perception. This problem doesn’t affect only architectural lighting designers. Film and TV directors of photography and lighting directors also rely on a light meter’s accurate measurement of brightness in their work, and when using colored LED fixtures the light meter is likely to be wrong. In fact, even white light LEDs can be difficult to measure accurately because of the blue spike in their SPD.

For now, the only way to accurately assess the brightness of colored LEDs is to see them in use. Lighting professionals need to let manufacturers and others know that the current situation is not acceptable, and that an accurate method of measuring and reporting the brightness of colored LEDs is a high priority. Talk to fixture and lamp sales reps, fixture and lamp manufacturers, and decision makers at IES, CIE, NIST and other research and standards setting organizations. There’s a solution out there. We need to urge those with the skills and resources to find it to get going!








Design Is A Process, Not Just A Product

I often tell my students that design is as much a process as it is a product. Even so, they (and some of my clients) sometimes want to go from first meeting to finished design in one step. I suppose one could do that, but the result wouldn’t be a thoughtfully appropriate design, it would just be fixture selection. The difference lies in the early part of the design process where we gather information about the project and the expectations of the stakeholders, followed by an analysis of that information towards the stated goals of the project. Only after completing those two critical steps can we begin the work of putting the design together and executing it. Here’s one way of looking at the entire process.Lighing-Design-Process








What Happened to IYL?

Elizabeth Donoff asks “International Year of What?” in her editorial in this month’s Architectural Lighting, and I have to agree with her.  Early last year I noted that our professional organizations showed no plans to take advantage of the International Year of Light, and indeed nothing worth mentioning happened.  The professional societies of the lighting community (IES, IALD, etc.) added the International Year of Light logo to their web sites, but that’s about all.  They held no significant events, published no important documents, and made no efforts to raise the visibility of the profession with potential employers (architects and owners) or with the public at large.  The IALD boasts that their regularly scheduled events were added to the IYL calendar, but say nothing as to what resulted, probably because the result was nothing.  Lightfair 2015 was business as usual, I saw no recognition of IYL.

The entertainment industry did no better.  United Scenic Artists Local 829, the union for theatrical designers, didn’t recognize the opportunities, nor did USITT, and at LDI (the entertainment industry equivalent of Lightfair) there was no sign that anyone knew about IYL.

As I’ve written before (see here and here, for example), and as many of us know, far too many projects are built with poor lighting because lighting design is seen as an added cost that can be avoided by having the architect, electrical engineer, or lighting sales person provide the “design” instead of a trained, professional lighting designer.  Hoping this will change won’t change this.  On an individual level, designers can educate their clients about the benefits of thoughtfully designed lighting, but it takes a larger, more expensive effort to reach those who don’t interact with lighting designers.  Only manufacturers or professional organizations have the resources.

What could they have done in 2015, or what can they do this year?  For starters, I’d like to see the IALD and/or the IES sponsor  sessions on lighting design at the annual conventions of organizations such as  AIA, ASID, and SCUP.  Let’s get in front of the decision makers and teach them about what good lighting can mean to them.  Topics such as energy efficiency, code compliance, and daylighting, as well as the more artistic and aesthetic sides of lighting design, are all appropriate and would, I think, be well attended.  If we want lighting design to be seen as an integral part of any building project we have to work at it.  Adding a logo to a web site isn’t enough.








Who Needs A Lighting Designer? Museums and Galleries!

A few weeks ago I gave a three-hour seminar on lighting museums and galleries to the graduate students in an art curating program at a university here in New York. Condensing everything I’d like to say into less than three hours was tough. The two big questions were what to include and what to leave out. I started with a quick overview of how to think about light and lighting before moving on to basic vocabulary and some common lighting techniques. Then, since LEDs are clearly the future, even when lighting art, I moved on to an overview of both color temperature and color rendering. I talked about reference materials such as the IES Lighting Handbook, intensity and brightness ratios, and other considerations before we moved into their gallery space to use their track light system for some demonstrations.

After the whole affair a faculty member, who sat in on most of the seminar, said he had hoped I would have spent much more time talking about how to use track lights and less time on unimportant issues like design, color temperature, and color rendering (!). I was respectful, but stunned. Focusing track lights is so complex that it requires extensive demonstrations? Understanding that with LEDs the color qualities of the light vary widely, and can only be properly selected when they are understood is unimportant information? Uhh…NO. Or, as my 20 month old niece says, “no no no no.”

Yes, five or ten years ago the default light source in museums was an incandescent or halogen lamp. The color temperature difference was minor and the color rendering of both was excellent. That’s not true today. Look at the cut sheet for any museum grade track light and you’ll see that you have a choice of several color temperatures and CRI values. If ANYONE needs to understand the qualities of light that must be selected when using LED fixtures, if anyone needs to understand the affect that color temperature and CRI have on how colors are perceived, it’s certainly people involved in displaying and lighting art. To me, that means the curators of exhibits and the lighting designers they hire.

As I’ve discussed earlier, changing the color temperature of the light changes the color appearance of objects, as shown below.

Illuminated with Warm White Fluorescent Lamp
Illuminated with 3000 K light

Illuminated with Cool White Fluorescent Lamp
Illuminated with 4000 K light

The phenomenon of color consistency means that the shift in color appearance isn’t as great as one might expect or as these photos suggest, but the shifts are real. If you’ve ever bought a black garment only to discover later that it was actually dark blue you’ve experienced this shift. A similar thing happens when we compare a high CRI light source and a low CRI light source. If your work involves color perception this is basic and critical information.

Curators can be forgiven for not knowing much about this, but if they know nothing how can they collaborate with their lighting designer to show the art as they intend? Administrators and curators of museums and galleries – educate yourselves, then hire a lighting designer!








Who Needs A Lighting Designer? Schools!

Studio T+L is the theatre consultant on the theatre in a new school here in New York. During an early meeting with the architect I explained that I prefer to have the dimming and control system for the stage lighting also control the house lighting, so I’d like to schedule a meeting with the lighting designer to talk about coordinating our work.

I wasn’t surprised (although I was disappointed) to be told that the design team for this new school building doesn’t include a lighting designer. Who’s designing the lighting in the classrooms, offices, theatre and other spaces? It’s hard to say. The plan is that one of the architect’s lighting sales representatives will present them with a choice of light fixtures, the architect will select the fixtures, and the electrical engineer will lay them out and circuit them. Unfortunately, this is an all too common approach that results in mediocre lighting, at best. Here’s why…

For starters, it’s highly unlikely that the architect has a deep enough understanding of vision, visual tasks, current fixture technology, control technology, code requirements, and the lighting design requirements of educational facilities to thoroughly evaluate the lighting needs of the school and the various types of spaces that it holds. It’s much more likely that the architect is working with a possibly outdated rule of thumb such as, “Schools should be lit to 50 fc.”   The sales rep, even if he/she is capable, isn’t going to invest any time or effort in a deeper evaluation of the school’s needs because the fixture sale (not good lighting) is the goal, so meeting the architect’s requirements is all that he/she has to do. The electrical engineer is simply implementing the architect’s instructions. He/she is given the selected fixtures and told to arrange them to provide 50 fc, and make sure to cover the code requirements.   What’s missing is any thought about how the spaces will be used and the actual needs of the occupants .

I believe that design is as much a process as it is a product.  A lighting designer would not assume that all school lighting is the same, and that as long as there’s enough light the lighting will be good enough. A lighting designer would talk to the school about their present facility, and about the good and bad aspects of the current lighting. The lighting designer may consult one or more of the available guides to quality lighting design for schools such as ANSI/IES RP-3-13 Lighting for Educational Facilities, and would look for opportunities to include daylighting as one element of the overall lighting design. A lighting designer would look at the sustainability and energy efficiency aspects of the lighting system and factor that information into the overall design. A lighting designer would take the time to understand how various types of classrooms are used, and would lay out fixtures and select controls accordingly.

I’m sure that none of this is happening on this school project.

And, not just any lighting designer will do. It behooves architects to have some understanding of the lighting needs for the building types they design to make sure the lighting designers they hire doing their job.  For example, my classes at Parsons School of Design in Manhattan are held in a building that is less than five years old.  It  that was designed by a prominent architect. However, the classroom I was in last semester had terrible lighting.  The room has two rows of direct-indirect pendant fixtures. The uplight and downlight components are controlled together, and all of the fixtures are controlled by one dimmer, so all of the lighting in the room works as one. The problem? The projection screen is bathed in light that washes out the image, and there’s no way to dim or turn off only the fixtures that affect the screen. There are lighting controls by the door, but none by the instructor’s computer station, so I find myself walking back and forth across the room to make adjustments to the light as I constantly balance my students’ need to see the screen with their need to see their notebooks. This is a rookie mistake, and any experienced designer worth his or her salt should have immediately seen the potential problem and selected fixtures, a layout, and controls to avoid it, but it didn’t happen.

So, who needs a lighting designer? Schools and the architects who design them.