San Francisco International Airport Janet Echelman Sculptures at Terminal 2

San Francisco, CA
Janet Echelman
Paul Zaferiou, Justin Brown/Lam Partners

Photo Credit: courtesy of Studio Echelman © Yan Yan Mao

The interesting part of the experiment was the characteristics of each light source. The incandescent had a CRI of 100, the maximum. The LED source only had a CRI of 40, way below the generally accepted range of good CRI for a light source. How is it possible that observers preferred the source with the lower CRI over a source with a CRI of 100?

To answer the question, first we must look at how we define color rendering. Color rendering is not just CRI. CRI is the color rendering index, and is not always reflective of a source’s ability to render color. Sources with the same CRI can have different spectral power distribution (SPD), and therefore render colors differently. For example, two sources, both with a CRI of 85, might have different short and long wavelengths, so that one source will render reds better, while the other source will render blues more vividly.

In order to define what makes up good color rendering, lighting designers must take into account the SPD of a source, the objects that are being illuminated, and the perception of the viewer.

Because CRI has limited ability to predict a person’s perception, another factor must be taken into account to determine a good luminous environment. That factor is called Gamut Area Index, or GAI. GAI is determined by plotting the chromaticity values of the eight color swatches used in CRI definition for a light source. The area of the polygon created by this plot is that source’s GAI, so the larger the area, the higher the GAI. High GAI is characteristic of a source with good color discrimination and saturation of colors, or vividness. Unlike CRI, GAI can be over 100, but this usually means colors appear oversaturated, and observer’s preference declines. In the experiment mentioned earlier, the preferred LED source had a GAI of 80, while the incandescent source had a GAI of only 40.

Examples of gamut area indices for various light sources. Each point of the polygon
represents the chromaticity of one of the eight color swatches used in traditional CRI
definition. The larger the area of the polygon, the higher the GAI of the source.

To ensure a good lighting design, designers should choose sources with high CRI and high GAI. The combination of naturalness provided by high CRI and vividness provided by high GAI ensure high viewer satisfaction for warm and cool sources, both at high and low levels of illumination, for either general illumination or accent lighting.

To achieve the best lighting design, one must also take the application into account. The question “what is being illuminated?” is critically important when choosing a light source. If the object being illuminated is red, you would want to specify a source that will render reds more vividly. But if the application is unknown, or will change over time, choosing a source with high CRI (85 or greater) and a high GAI (80-100) is generally the best approach.

Image credits: Alicia Miksic (1), Lighting Research Center (2)

Photo Credit: Lam Partners

Yesterday was the winter solstice. It is a time that we often associate with Christmas, Yuletide, Hanukkah, or the Feast of Saint Lucia. Candles are lit, trees and rooftops are decorated with strings of light, parties are held, and gifts are exchanged. The lighting of lights to relieve the cold and dark of this time of year symbolizes hope and perseverance. It might be surprising, then, to learn some of the other ways that the longest night is celebrated throughout the world.

The word “solstice” is derived from Latin words meaning “the standing still of the sun”. While the winter version is most commonly referred to as the shortest day of the year, it is actually a point of inflection which occurs at a specific time: this year it was December 22 at 5:30 UTC. The time refers to the precise moment when the northern hemisphere has reached its furthest distance from the sun before dramatically shifting directions.

Historically, celebrations surrounding the solstice are as much about this critical turning point as they are about darkness and light. Many, such as Goru among the Dogon people of Mali, mark the end of the harvest season and the beginning of winter.

Other traditions, however, reflect the transition by taking on a subversive form, where participants engage in activities that upend the standard order. Bacchanalian festivals in Ancient Rome and Greece such as Brumali or Saturnalia were times of casting off social restraints, of drinking and merriment, and of some other, more unusual, customs: slaves would enjoy a banquet served to them by their masters.

This reversal of order is achieved elsewhere by wearing disguises. In the Junkanoo festivals celebrated in the Carribbean, parades feature elaborate, symbolic costumes. The Cornish custom on Mummer’s Day is to march through town with blackened faces or masks. In several traditions, ghost stories are told, and spirits are said to haunt the living, as in the Scandinavian Feast of Saint Lucia, during which the demon Lussi is said to frighten children who have not been good.

Other cultures simply embrace the longest night by staying awake for its duration, such as the Persian festival Yalda, or Shab-e Chelleh, in which families gather together to feast on pomegranates and dried fruits, stay up all night, and listen to poetry. Celebrating throughout the night was also the custom of the Inca and of the Mapuche of Chile (though their rituals for the longest night of the year in the southern hemisphere took place on the opposite solstice in June). The observers would stay up several nights waiting for sunrise, celebrating the assurance that the sun would return.

The eventual triumph of light over darkness and the symbolism of renewal are some of the strongest themes prevalent in these celebrations. Sol Invictus from the Roman Empire translates as “the undefeated sun”. The Kurdish _ewy Yelda portrays the sun as being reborn after the solstice. In contrast, Dong Zhi in China celebrates the “arrival of winter” and the interrelationship between darkness and light as part of the yin and yang philosophy. Families gather, and a sweet soup made with pink and white rice dumplings is served.

While we often think of the winter solstice as simply the shortest period of daylight in the year, throughout history and the world, there is a richer picture. However you are celebrating, have a happy solstice.

Photo Credits: NASA Goddard Space Flight Center (1), Andrea Rota (2), Antoine-François Callet – Musée du Louvre (3), MissChatter (4), Fredrik Magnusson (5), Eliza Tasbihi (6), Oranje (7)

Lighting of exterior environments not only provides for safe navigation during hours of darkness, but can reveal design elements, both built and natural, that are lost in daylight, returning delight to the hours without sun. With all of our energy focused on lighting the ground, the importance of vertical illumination is getting lost in the darkness.

Early versions of LEED SS Credit 8 (Light Pollution Reduction), with stringent requirements to limit all light above the horizontal plane with the exception of very low-brightness fixtures, was an effort to push dark-sky agendas forward without acknowledging what a well-lighted exterior environment actually requires, or what it contributes to the urban environment. Downlight with sufficient uniformity can facilitate movement across plazas and walkways, but where are people headed? Lighted pavement alone can provide orientation only without end or destination.

While obscuration of the heavens through urban sky glow is one of the most unfortunate results of the urbanization and industrialization of our planet, the metrics for nocturnal illumination cannot be based upon the assumption that the primary task of humans in an urban environment is to go and gaze at stars. Even when these standards are met, the results can still have a negative impact: a modestly lighted parking lot with light-colored concrete pavement lit to the minimum IES recommendations, using only cut-off fixtures, can substantially degrade a dark residential environment if that pavement is within view of residences – and the reflected light from the pavement is going into the sky, even though the fixture itself does not emit light above horizontal. (This is a great opportunity to advocate for tree cover – not only does it provide parking lots with cooling shade during the summer and soften their appearance during the day, but it blocks reflected light from trespassing upwards! That’s not accounted for in the requirements).

The Lighting Research Center at Rensselaer Polytechnic Institute has developed a metric for evaluating and designing exterior lighted environments, known as Outdoor Site-Lighting Performance (OSP), that accurately documents the effect of electric illumination on a project. OSP acknowledges that glare, light trespass beyond the physical limits of the site, and sky glow are all important factors that warrant consideration. However, by using modeling tools that measure the amount of uplight trespassing off the site – not only light emitted by fixtures, but also the reflected light off of surfaces such as the parking lot mentioned above – a more realistic picture of the lighting effect can be examined. Similarly, current and future versions of LEED SS Credit 8 do allow for some amount of uplight in the urban environment.

What about projects where reliance on cut-off downlight fixtures is not a good fit architecturally? Can they still meet the intent of a sensitively lighted nighttime environment? Lam Partners’ Hermann Park Lake Plaza project avoides pole-mounted fixtures, equipment that is, in effect, prescribed by LEED and other dark-sky guidelines. Determined not to use pole-mounted lighting along the water’s edge to avoid distracting reflections in the water, the designers devised a fully integrated approach. One-watt LED button steplights illuminate and guide, tracing the arc of steps around the lake; ground-recessed ceramic metal halide tree uplights create a welcoming border.

The graceful composition remains uncluttered by hardware, focusing solely on form and line. The arrangement is serene and contemplative in early evening, then emerges dazzling and energetic as night descends. Because awakening the appearance of surfaces and landscape forms was critical to attracting visitors after dark while fostering safety and security, tree trunks and wall surfaces are boldly illuminated.

The team deliberately relinquished the LEED light pollution credit (although the project did achieve LEED status), and yet, the uplit trees are magical during nighttime strolls. As darkness conceals architectural stonework, the wooded procession comes to life through light. From across the lake, the trees form an illuminated horizon, and indirectly lighted walls form the edges of this exterior room.

Photo Credits: Anton Grassl / Esto (1), Walmart Stores (2), Overland Partners (3, 4)

Chazen Museum of Art

Madison, Wisconsin
Machado and Silvetti Associates with Continuum Architects + Planners
Paul Zaferiou, Jennifer Pieszak//Lam Partners

Photo Credit: © Lam Partners Inc

No one can dispute that AGi32, Photoshop, and Illustrator are a lighting designer’s best friends, but as we strive to give clients more reasons to demand lighting design, we should be looking at new ways to convey lighting design’s importance.

Until a few years ago, animation or video seemed too expensive and impractical for all but the most critical circumstances. Today, however, these are becoming integral tools of our trade. Tools and techniques are becoming available that previously only highly skilled animators and film editors had at their disposal, and they are easier to use than ever before. Software like QuickTime and Photoshop allows easy access to impressive tools for composing ideas into dynamic form. More sophisticated software like After Effects and 3ds Max allows limitless possibilities. Documentation of elements in the analog environment can also be helpful and illuminating. Most digital cameras and phones have video capabilities, making it easy to spontaneously capture anything.

There are a range of out-of-the-box animation tools readily accessible today. Shadow studies are one of the most effective means of beginning a discussion about daylighting strategies with a client. These simple studies can be performed in any number of programs like Google SketchUp, AGi32 , or Revit. Photoshop and QuickTime have functions which allow the user to string a series of still images together to form an animation. For example, they can be used to show design variants, transitions from daylighting to electric lighting schemes, different lighting scenes over the course of a day or night, or the effects of colored light on a space. Programs like 3ds Max, DIVA-for-Grasshopper, and After Effects or Premiere allow even more options.

The economics of animation and video can still be a challenge. It is difficult to set aside time on a project to learn and employ new methods, but while we always have to keep the bottom line in mind, animation can be a more efficient way to convey information. The video format may elucidate questions the client hasn’t formulated or uncover costly issues that might otherwise come up later. Like the saying, “a picture is worth a thousand words,” perhaps, literally and figuratively, a video is worth a thousand pictures.

While it is true that new technologies always involve some level of time invested in learning them, I would argue that it seems well worth it, given the obvious needs in our industry, and these new techniques may eventually make getting your point across to the client more timely and efficient. Animation can help build a client’s confidence in a design, and it can reveal lighting’s capacity to alter the feeling of a space dynamically, in ways that the client may not have imagined.

Image and video credits: Kera Lagios / Lam Partners

I’ve been thinking about the relationship between simplicity and complexity in design. Why do some design problems initially appear simple but then upon investigation, turn out to be very complex? Why does the solution to a complex problem often, after lengthy analysis, turn out to be the most simple answer? Or why does it sometimes take a very complex technical solution to produce an elegantly simple visible end result?

During the design and construction of a recently completed project, I asked myself some of these questions. Although I don’t have all the answers, this project provides some examples to demonstrate what I’m talking about. The project is the United States Institute of Peace in Washington, D.C., designed by Safdie Architects.

Here is one of the design challenges presented to us: make it look like the architectural model – make that translucent roof glow at night. And, oh by the way, you have to light the space underneath at the same time. It seems simple, right? But it’s really complicated.

We did lots and lots of computer modeling to test out different ideas. Now, you’re probably wondering, why is there a picture of the Lincoln Memorial? Well it turns out, the roof couldn’t be any brighter than any of the surrounding monuments and memorials, so we had to do a complete luminance study and a presentation at the National Capital Planning Commission to show that our roof wouldn’t be any brighter than the memorials.

Then we had to estimate the transmittance and reflectance of the roof, and it turned out the roof system was going to be in two layers: an outer layer of translucent glass and an inner layer of fabric membrane. So, estimating this was actually quite complicated because of the inter-reflections. We started with back-of-the-napkin sketches and then moved on to tabletop mockups with some of the possible materials for the roof.

Then we moved on to full-scale mockups, and these had to be done in Germany because that’s where the roof was being built (at Seele, outside of Munich). First we looked at the mockup in daytime to see how the different combinations of possible inner and outer materials would perform.

Then we tested the different material options outdoors at night with the proposed lighting solutions. And we did visual evaluations of how it looked outside and inside, took all kinds of meter readings, and of course when we were done, since we were in Munich, we had to have a beer!

So after that very complicated design process here is the solution – really simple: for the interior portions of the roof, linear fluorescent forward-throw cove fixtures. And for the exterior overhangs, in-ground metal halide adjustable accent lights.

And here’s the visible end result: very simple and elegant. Architectural forms are revealed and the space is well illuminated. I knew we were successful when a visitor said to me, “So, you’re making the roof glow, but I don’t see any light fixtures.”

Moshe Safdie’s vision was realized, and we’re a good neighbor to the surrounding memorials and monuments. So was all this complicated design process really necessary to reach this beautiful end result? That’s what I’m thinking about. I think it was. All the modeling and mockups and testing and head-scratching gave us much, much more confidence that our very simple solution would work. Without it, I think we would have been inclined to make the solution much more complicated, and in the end, that could have given us a final result that was cluttered and incoherent.

Photo Credits: Safdie Architects (1), Glenn Heinmiller/Lam Partners (2-10)

Union First Market Bank

Richmond, Virginia
Baskervill
Paul Zaferiou, Matt Latchford/Lam Partners

Photo Credit: © Lam Partners Inc

Continued from Lighting Design and Revit: Part 1.

Earlier versions of Revit were not really optimized for use in a linked, work-sharing environment; even so, architects, engineers and other consultants in the design trades quickly recognized its value. Strategies for linking each other’s models together efficiently and effectively had to be worked out very early on in a project to keep the design process unimpeded. Later improvements in the software indicated that the developers were aware of the demand for better work-sharing tools and implementation. Now in version 2012, Revit has many new features and functions that greatly improve the ability to host elements to linked geometry.

This makes hosting light fixture families to the geometry of an architect’s model vastly easier, however, it also points out areas that still need attention, namely the fixture families themselves that manufacturers are making available. Previously, before work-sharing was prevalent, many lighting fixture manufacturers only offered ceiling- or wall-hosted families that would not work within a linked model. As it becomes understood that outside consultants now have the ability to host fixtures to linked models, manufacturers are beginning to offer face-based fixture families as well.

Despite all these recent improvements, there is still a tremendous amount of work to do and uncharted territory for lighting designers to navigate. Fixture families from outside sources almost always require modification, shared parameters need to be established with the electrical engineer, a usable fixture schedule needs to be generated, and in-house standards are needed that can be easily adapted for various projects – these are just a few examples. Each project team is still going to have a unique dynamic, with each team member offering different skills, so some flexibility is necessary to truly optimize workflow.

After recently completing what can be called our first Revit project, I realized that we provided all the same information to our client as with previous non-Revit jobs, but in a format that required a lot more upfront consideration and a more thorough understanding of the building’s geometry. Stepping back, I can see that our design is cohesive and well-considered; there’s a connectivity throughout that I think is due in part to the nature of the software.

Now to work on customization and templates to get Revit to better match our project management style!

Image credit: Jenny Cestnik