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)

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)

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)

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

Controls: use them!

It’s really not acceptable to use simple switches and whole-floor relays anymore. Some energy codes may still allow it, but that doesn’t mean it’s good practice. Have you ever walked around a city at night and looked up at the skyscrapers to see entire floors, or even whole buildings, with all the lights on late at night? Chances are there are only a handful of people there, or none at all. Sensor technology has improved a lot over the years and should be applied liberally to take care of all those lights that no one is there to use. It not only saves electricity, but the time, effort, and additional energy it takes to replace lamps that burned out too soon from overuse.

Make sure you use sensors correctly, too. If a sensor is placed behind a bookshelf, it’s doing no good back there. If you put one right in front of a door and the light stays on all the time, how it that helping? There are a few simple tricks that the manufacturers can educate you about to create good sensor design.

And, consolidate your sensors. Most sensors can be used for both lighting control and HVAC control. Instead of two sensors in a space, use one.

K.I.S.S. – keep it simple, stupid!

Lighting controls can be daunting. Even the simplest systems have gadgets, widgets, and enough wiring diagrams to make the savviest engineer’s eyes go crossed. When selecting the system you want to use, make sure that price isn’t your only deciding factor – consider how easy it is to design, install, and program. Making people’s lives easier will result in a higher probability of your controls design being implemented the way you designed it.

Minimize the amount of wiring you need to make your system work correctly. Wiring in any given building can add up to hundreds or even thousands of miles, if you tied it together and stretched it out. Any way to reduce that raw material used (and the energy used to make it) helps. If one system uses 40% less branch wiring than another, consider it.

One of the core fundamentals of the design community is collaboration. Whether it be among multiple designers within a single office, or between the architect, consultants, and of course the owner working towards the goals of a project, a design is never fully visualized and constructed without careful collaboration of resources and ideas.

As individuals within that community, we constantly strive to gain more knowledge, increase our experience, and share our ideas. Design is a two-way street (sometimes a never-ending rotary), with a constant ebb and flow of concepts and diagrams. Being a singular designer isolated from the richness of team thought and continued education would result in stale work and short careers. That’s why we all attend Lightfair and IALD or AIA conferences, and go to lectures and seminars – to see what others are doing and thinking. These activities are about much more than just earning CEUs; they are also about networking and socializing, for it is these aspects that really stimulate our interests and further our careers.

Every time I attend Lightfair, I’m intrigued by the new products that are coming to market, but I’m always much more interested in, and inspired by, hearing about what others are working on, or seeing projects they have recently completed. Keeping in touch with colleagues and being a part of a community (one that’s much larger than your daily isolated focus on project-specific tasks) keeps us fresh and invigorated to strive for more or to do better work. This is not about keeping a watch on our competition – it’s about constantly seeking inspiration to enhance the built environments that we design.

Unless you’ve been under a rock lately or you still have a dial-up modem, much of this inspiration can be found online or in the palms of our hands.

For years now, we’ve turned to blogs and websites to share our ideas and to seek inspiration. It is this constant search and self-education that makes design so much fun. There are many bad answers, but there is no single right answer that solves all of our design challenges. If there were, buildings would never evolve, design would grow stagnant, and the design community would be extremely small, populated by the lucky few who first found that ‘right’ answer.

Fortunately, much of what makes design so challenging and fun is the actual process and not just the final answer. So take a minute and view some cool, thought-provoking images, reconnect with a past colleague, or listen for a clever birdie, and you may be surprised by how much out there is useful and influential.

I am certainly not one of those at the forefront of the social networking phenomenon that is upon us (I don’t even know if I am close enough to see the back of it), but I am excited by all of the endless digital media that now exist to generate the same interest, intrigue, and inspiration that I always sought, and will continue to seek, from a global design community. Sharing our ideas, listening to the experiences of others, and trying something new is what makes each of us better designers and each of our projects more successful. I haven’t seen that ‘perfect’ project yet, but I will continue to seek out ideas to improve the built environment that we all create and live in.

Image Credits: Twitter, Inc. (1), William Wayne Caudill (2), public domain (3)

Strike a balance between efficiency and functionality

The efficiency of a light fixture or system is not a replacement for functionality and aesthetics. On the other hand, the beautiful appearance of a chandelier does not mean it should be an energy hog either. Know where to pick your battles and try as hard as you can to design lighting that’s as efficient and beautiful as possible – together.

Having said that, do look for fixtures with 75% efficiency or better – certainly no lower than 50%. Not everything will conform, but if the bulk of your lighting exceeds this benchmark, you’re doing pretty well in getting the biggest bang for your electrical buck. As always, weigh efficiency against function – if it’s glary, those extra percentage points aren’t helping.

LEDs, coming soon…

LEDs have the awesome potential to the be next big thing in the lighting world. At the rate the technology is improving, they may be set to take over the fluorescent market in the next five years. But beware of false claims: make sure you’ve personally tinkered with any fixture you’re going to use on a project, and don’t forget to find out what it really costs – you may be shocked. Just as there was hesitation to adopt the early compact fluorescent bulbs because of their poor performance and color, we’re seeing the same with LEDs. Give them time and they will wow us, for real this time.

Do your homework. You don’t want a call from an owner in two years saying that they can’t replace a light source because it failed prematurely and they’re not available anymore; that whole fixture would have to be scrapped and replaced. Try to future-proof your designs.

Mind the costs.

Greener buildings are touted as being more expensive than traditional spec buildings, and that may well be true. But, good, efficient lighting doesn’t have to be part of that added cost. Mind your dollar-signs when selecting fixtures, and make your clients see that it’s the padding of the bill that jacks up the price, not the hardware. Of course, if you do pick a really expensive fixture, you’re on your own.

Reduce, reuse, recycle

First, don’t over-design – the more over-designed a space is, the more raw materials and energy it will consume. Building designs can’t accommodate every possible use. Designers need to pick the function of a space and stick with it, with exceptions for truly multi-purpose rooms.

Second, if designing for a large institution, especially renovating a space, ask if they have attic stock that you can use on your design. They’ll love you for not spending money, and you save manufacturing and shipping energy. That doesn’t mean you can use A-lamps instead of fluorescents, but if it fits the design, use it. That goes for controls, too. How can you augment an existing system to perform its new task even better?

Third, recycle: recycle old fixtures, recycle lamps, recycle control systems, recycle everything you throw out during a renovation, new construction, or simple maintenance task. Fluorescent and metal halide lamps, especially, need to be recycled as toxic waste. They both contain mercury, a neurotoxin, and we don’t need that in our water supply. Find your closest lamp recycler.

Like it or not, BIM – by which I mean Revit – is here to stay. For smaller firms, Revit may represent a daunting hurdle to overcome, in terms of both cost and learning curve. While I agree the cost is high, once I began to understand how the software functions, I realized it actually forces the entire design team to work in a much closer and more collaborative way; in other words, more like how projects were done before computers.

While claiming that an expensive software platform can actually replicate the design process of yesteryear may seem like a bit of stretch, there are some interesting parallels. Revit functions as a stand-alone tool, but really shines when all the team members using it interact and communicate regularly. Until a project can live reliably on a cloud server so all team members can access the model simultaneously as originally intended, the various disciplines now work on separate models that get linked together on a regular basis to coordinate and resolve conflicts. This regular interaction enables team members to observe each other’s progress, gaining valuable intimacy with the entire project, not just his or her own area.

This current process works reasonably well for the main players on a project – the architect and MEP and structural engineers – but what about lighting, which is such a critical component of a successful project? Shouldn’t lighting also take advantage of Revit? How can a lighting design firm effectively interact in an increasingly BIM-oriented work environment?

As I quickly found out, nobody had really thought much about how smaller consultants could successfully provide Revit deliverables, so we continued to issue 2D CAD lighting layouts that were then recreated in the model by the architect. Eventually it became apparent that this method didn’t make sense, and we began to actively explore a simple and effective workflow with our clients using Revit.

Next month: Part 2.

Image credits: Jonathan LaRocca (1,2)

Only a little direct sun, please

Too much direct sunlight increases the indoor temperature, creating higher cooling loads. It also increases the potential for glare. If there’s too much glare, people are likely to pull the shades and leave them that way, which equals no more daylighting! Most interior shades do little to reject the heat load. Consider using exterior overhangs to keep excessive sun outside, and light-shelves to distribute the daylight indoors so it’s more useful.

Don’t add complexity and cost by creating one problem and mitigating it with another technology. The New York Times Building has been criticized for this. Its floor-to-ceiling glass has the potential to let too much light and heat inside, so the ceramic tubes outside the glass were introduced to help block some of it. If you have less glass to begin with, you can use less exterior shading… If you can afford it and don’t care, then have at it, as long as you keep your energy use down. Otherwise, try not to pile on unnecessary complexity chasing an aesthetic.

Installing shades is not daylighting

Simply installing internal glare-control shades or blinds is NOT a form of daylighting. Neither is using a lot of glass just to get more light inside. The façade of a building must engage the sunlight to utilize it in a meaningful way, coaxing the useful light in while controlling excessive light and rejecting heat. This means articulated façades, not flush glass.

If you do use shades, make them automated if you can afford it. Automated shades can adjust for different lighting conditions throughout the day, and they don’t rely on a forgetful occupant to pull them back up. If you can’t afford automated shades, try to design your envelope with external shades or a light-shelf such that you can keep the upper part of the window open all the time and still allow manual shading below it.

Dimming the lights

Daylight switching is no replacement for daylight dimming. Switching has a tendency to irritate occupants, because it flips the lights on and off throughout the day when the ambient light is near the threshold light level. More often than not, if it doesn’t work correctly, it will simply be disabled instead of fixed. You definitely can’t rely on people to make the best choices on an hourly basis either – the lights go on and stay on all day. Flipping a switch is what we’ve been trained to do all our lives.

Rely instead on dimming your perimeter spaces. There are variable levels of savings to be had here, from actual energy savings, to rebates just for putting daylight dimming systems in. Every little bit helps in terms of energy – initial cost is a different matter. There may be legislation or changes to the building codes in the near future that would require you to use daylight dimming anyway.

Digital is in!

All the ballast manufacturers, and a few lighting controls manufacturers, are finally, albeit slowly, switching over from older analog technologies, to digital or hybrid analog/digital systems that operate with greater precision and functionality. If you use one of these emerging technologies, your system is more likely to still be in style in the next decade or so (but don’t jump the gun on a brand-spanking-new product, lest it be discontinued). DALI is one of those technologies; it’s been around for about ten years now, and is slowly catching on in the US.

Don’t go crazy

Just because dimming is warranted in daylit zones and conference rooms, doesn’t mean you should use it everywhere. Some advocates claim additional energy savings by being able to dim the lights everywhere, but that would only be if you’ve over-illuminated your interior spaces to begin with. Design them correctly and you can save a lot of materials and costs. Dimming everything is another example of mitigating a problem that you may have created yourself.