MIT Creates Incandescent Lamp As Efficient as LEDs

Researchers at MIT and Purdue University have demonstrated an incandescent lamp with an efficacy of 6.6 percent, and with a potential efficacy as high as 40 percent. The paper was published in the April issue of Nature Nanotechnology. The demonstration compares favorably to current low efficacy fluorescent and LED lamps, while the upper limit is double the current maximum efficacy for fluorescents and LEDs.

The lamp uses a flat filament, rather than the coil of typical incandescent lamps, that is held between two plates of glass with a coating similar to a dichroic reflector, which the researchers call a photonic crystal. The plates permit visible light to pass through them, but reflect the infrared light back to the filament further heating it and producing more light. This idea has been with us for a while now, with most major lamp manufacturers producing some version of an IR halogen lamp. The main difference is that the new dichroic-like coating is much more efficient than the coatings currently in use and works at a much wider range of wavelengths and angles.

This is great news for those of us who haven’t bought into the idea that LEDs will make everyone happy, make all of our children above average, and help the country win the war. Between the low LPDs of the current versions of Standard 90.1 and other energy conservation codes, and the high efficacy of LEDs, most of us are compelled to use LEDs as the primary light source in many of our projects whether we want to or not. LEDs are great, but they’re not the best design choice for every application. As my students and readers of my book know, I regard energy efficiency as an important consideration in any lighting design, but not the primary goal. My first goal is to understand and deliver the desired look and feel of the space I’m lighting while providing appropriate light levels. My second goal is to explore the possible techniques and technologies that I can use to achieve my first goal. My third goal is to use the most energy efficient option from among the best options.

As a designer whose primary concern is the quality of the living/working/shopping environment I’m helping to create, I want to have as many tools at my disposal as possible, not just LEDs. At this point, it seems that lamp and fixture manufacturers are fully embracing the LED with very little attention paid to other light sources, with the possible exception of the OLED. If this experimental lamp becomes commercialized, we’d be able to use inexpensive, tried-and-true dimming technologies that deliver the performance we want without any of the problems associated with fluorescents and LEDs (flickering, flashing, dimming curves that are too flat or too steep, inability to dim smoothly to 0%, high cost, etc.).

This lamp wouldn’t be a solution for all lighting situations of course, in the same way that the LED isn’t a solution for all situations, but it would allow us to have true incandescent light in any application that called for it without running afoul of energy conservation codes. The best of all possible worlds!

IES Symposium Summary

If you missed IES Research Symposium III Light + Color you missed an exciting (for color geeks) few days. It would take too long to relate everything that was discussed, but here are some key highlights.

  • TM-30-15 is seeing broader acceptance throughout the industry. In an exciting development, it seems that the CIE is going to endorse TM-30 Rf after a few changes are made. The expectation is that the industry will then begin a rapid movement toward using Rf instead of CRI Ra, and that eventually CRI will be withdrawn. Unfortunately, the CIE is notoriously slow, so there is no timeline for their formal endorsement of TM-30. Maybe next year?
  • Manufacturers are resolving the spectral deficiencies that result from using a limited number of LEDs in both color mixing and color temperature tuning products. Their solution is to move from two and three color systems to systems using four or five independently controlled colors of LEDs.
  • Color preference was a big topic with no resolution. One complaint of both CRI and TM-30 is that they penalize light sources that deviate from the reference source even if many people prefer the deviation. Of course, Ra and Rf are both fidelity metrics, so they must penalize such deviations.   We have strong evidence that people prefer light sources that slightly increase the saturation of objects, and that people prefer light sources that include somewhat more red than the reference sources. However, because the amount of deviation that is preferred is application dependent, a single, all-purpose metric for rating color preference seems to be unattainable.

Southern Comfort at the Public

Our own Ed McCarthy is the lighting designer for Southern Comfort, which is playing at the Public Theatre through March 27th.  Charles Isherwood says that “This cast is entirely winning.”  So is Ed’s lighting design!  Read Isherwood’s review in The New York Times.

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  AIAASID, 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.