Tag: DAYLIGHTING

All Posts in “DAYLIGHTING”

Project Profile: Kauffman Center for the Performing Arts

October 22, 2012 / no comments

The Kauffman Center for the Performing Arts houses a state-of-the-art concert hall and
performing arts theater, wrapped by a soaring glass-enclosed lobby.

A striking new addition to the Kansas City skyline, the Kauffman Center for the Performing Arts houses a state-of-the-art concert hall and performing arts theater, wrapped by a soaring glass-enclosed lobby. Safdie Architects worked with BNIM Architects to design the approximately 285,000 square-foot structure. In addition to beautiful performance spaces, the Kauffman Center also contains offices, rehearsal space, warm-up rooms, and dressing rooms.

Cholera Treatment Center in Haiti

July 9, 2012 / no comments

Recently we were asked by MASS Design Group to do a daylighting study for their new Cholera Treatment Center (CTC) in Port-au-Prince Haiti. This is the second time that we have had the opportunity to work with them. Since the earthquake on January 12, 2010, Haiti has suffered enormous economic, structural and environmental distress. Cholera, which previously did not exist in Haiti, broke out shortly after the earthquake and according to the World Health Organization, as of November 30, 2011, there were 515,699 reported cases of cholera and 6,942 deaths.i The new CTC will be a year-round center for the care and treatment of patients suffering from the illness. This project presents an unusual opportunity to engage lighting on such fundamental levels, and to think about basic human needs as they relate to light. It’s even more unusual to be facing these issues in a country like Haiti. As designers in the United States, our typical projects include commercial, residential and institutional projects in major developed cities. While many basic principles of good lighting remain universal, working on a project like this exposes us to significant cultural, financial and climatic differences.

What we learned

MASS Design Group is a non-profit architecture and design firm dedicated to helping improve the health and overall well-being of communities through design. Their most well-known and highly-praised projects include the Butaro Hospital and the Girubuntu School, both in Rwanda.

During our design conversations, members of the MASS team shared with us examples of the kinds of design and technology challenges that they have encountered in their work. One team member, Elizabeth Timme, shared a few experiences from Butaro Hospital. The hospital is tailored for the treatment of tuberculosis, so enormous fans are suspended from the ceiling and UV lights shine from the walls. The fans keep air moving (a critical element in tuberculosis treatment), and the UV lights kill airborne bacteria. Patients however, worried that the fans were “stealing their air” and that the lights were “burning their skin”. To some extent both comments are true, but negotiating the relationship between the function of the space and the occupant use and comfort highlights a fundamental mission of design.

For decades Western hospitals were built to enhance efficiency and hygiene, and only recently has there been more evidence that daylight, views and good design are equally critical factors to providing the best health care. In fact, Timme is now starting her own firm, Más, in order to bring a similar design approach as used at MASS to the issues facing the American health care system.

MASS has encountered other issues that have to do with climate and resources. In one case, they told us that in Rwanda, surface brightness was a serious design consideration. The sun at that latitude can cause surfaces to be so bright that they create visual discomfort. An article by Martin Schwartz about Louis Kahn’s proposal for a U.S. Consulate in Luanda illustrates this issue. In it Schwartz quotes Kahn:

“I …noticed that when people worked in the sun-and many of them did-the native population …usually faced the wall and not the open country or the open street. Indoors, they would turn their chair toward the wall and do whatever they were doing by getting the light indirectly from the wall.” ii

Not only do these types of realizations help us to understand better how to work in under-served countries, but they help to inform our approach to design for our typical projects. Working on a cholera treatment center can help us to recognize and consider factors in our day-to-day work that we may not have previously considered to be important or necessary.

What we did

The center is 7,700 square feet and consists of a general ward, an intensive care ward, as well as an administration office. The roof consists of 15 roof modules, each 23′ x 23′ oriented in different directions. Four central modules serve as the top of a cistern designed to collect water, while the remaining 11 are pitched, both to allow for light and ventilation as well as to direct water towards the cisterns. The building is primarily open on all sides, although there are fixed screens on the North and East sides and sliding screens hung on the West side.

Since construction had already begun when we joined the team, the project manager, David Saladik, emphasized that we needed to quickly and efficiently produce a series of clear and useful daylighting studies. There was no possibility for bells or whistles. We had to make simple and effective recommendations that could be executed within the time and resources available. It was important to set our criteria immediately, and use tools that would help us achieve our goals. For all of the simulations we used the daylighting program DIVA-for-Rhino.

Our analysis focused on three key issues: sufficient light levels, glare, and heat gain. To test for adequate light levels, we ran a daylight autonomy test using a horizontal calculation grid at the height of the beds, and vertical grids at the headboards. We used a threshold of 500 lux because light levels need to be relatively high, since nurses and doctors will be conducting procedures and treating patients at their bedside. We were pleased to see that the daylight autonomy results for the existing design showed that we can expect 500 lux over the majority of the ward space for 50% of the year.

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Daylight Autonomy calculation (500 lux threshold)

Having established a general sense for annual daylight levels, we wanted to look more closely at the lighting conditions during specific points in time when we could estimate there might be problems. The East side is most vulnerable to overlighting and heat gain because there are no structures directly to the East of the center. We wanted to test a variety of material options for a proposed set of panels, which would serve as shading. We chose three materials to test: opaque panel with 50% reflectance, a translucent panel with 40% transmission, and 40% open screen.

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Evalglare Glare Analysis

Summer Solstice 9am Glare Analysis 40% Open Screen (top right)

Winter Solstice 9am Glare Analysis of (3) different panel options (bottom)

Our results show that only the opaque panels will have a significant effect on minimizing the overlighting on the East-side ward. The translucent and 40% open screen still allow a significant amount of light and, by extension, heat into the building. In addition, when we ran the glare tests for the three material options, the 40% open screen performs the worst in terms of glare for the patients in East-facing beds. This only gets worse during the rest of the year when the sun is lower in the sky; on the Winter Solstice at 9am, the Evalglare Daylight Glare. iii Probability result showed there would be intolerable glare . Since the preferred solution is to use the screens, we recommended modifying the open percentage of the screen to be less than 40%.

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Glare experienced from hospital bed on Summer Solstice at Noon (bottom left)

Roof module and assembly (bottom right)

Cholera outbreaks in Haiti are the most frequent during the rainy season, which happens in the summer. Knowing that, we were particularly interested in the summer conditions since those are the times the wards will likely be most full. In particular, we looked for problems with glare and overlighting. The orientation of the roof modules on the East side allowed, rather than prevented, direct early morning and noontime sun to stream into the building. We confirmed this by running several glare simulations, and made the recommendation that two of the roof modules be rotated 90 degrees in either direction to eliminate the problem.

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Illuminance Calculations Summer Solstice 12pm

Existing Glazing Design (left). Glazing replaced with 80% Opaque Panels (right)

The last issue we wanted to tackle was the glazed portions of the roof that would direct water into the cisterns. Those sections would be glazed in order to let light into the center of the building, and be directly above a small, planted garden. We ran several tests on the Summer Solstice, which showed that there would be dramatic overlighting, glare and potentially great heat gain. While we understood the design intent to create a small lush area in the middle of the ward, we suggested some simple louvers to mitigate the quantities of incoming daylight.

While absent of high-technology or complicated details, our solutions answered the key daylighting questions and will contribute to providing the patients and staff with the most functional and comfortable space possible. Even with the demanding constraints of a project like this, in the end, we’ve shown that with targeted thinking and the right tools, we can come to useful conclusions and make effective recommendations, which is definitely a lesson we can bring back to our everyday work.

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i World Health Organization, “Health Cluster Bulletin: Cholera and Post-Earthquake Response in Haiti”, 21 December 2011.

ii Louis I. Kahn Writings, Lectures, Interviews, page 123, quoted by Martin Schwartz in “Louis I. Kahn: Finding Daylight in Luanda”, February 7, 2011.

iii Evalglare calculates glare according to several factors such as brightness and size of glare source, and gives a result called the Daylight Glare Probability, which was calibrated by user-assessments. The categories of glare perception from least severe to most are: Imperceptible, Perceptible, Disturbing and Intolerable. For more information see: Evalglare.

Image Credits: Kera Lagios/Lam Partners

Choosing Glass for Daylighting

July 5, 2012 / no comments

Glazing for daylighting needs to be chosen both for its visual character (clear, diffusing, etc.) and its technical light-transmission values. Commonly, the visual decision will come first. Do we want clear glass, complete diffusion, or something in between? Diffusing glass has its applications, but needs to be used with care. While it’s tempting to “solve” the problem of diffusing sunlight and controlling direct sun glare by using diffuse glazing, that glazing itself can also become a source of glare. Diffusing glazing with high light transmission, such as Kalwall, can be dazzlingly bright if it’s exposed to direct sun. If that’s in our field of view it can be a worse source of glare than the sun through clear glass because, unlike clear glass, it’s bright from all viewing angles. And of course diffuse glazing destroys outside views, which can be as valuable for well-being and productivity as the daylight itself. For these reasons, fully diffusing glazing is best used where it is not in direct view. Opal frits and silkscreened interlayers can provide a combination of diffusion with some clear views, however they may still become glare sources, similar to fully diffusing glazing. So let’s assume we’ve chosen clear glass (whether tinted or not) for its visual character – now what light-transmission values do we want?

All practical sources of illumination contain a mixture of visible light energy and non-visible energy. What happens to the energy in daylight after it enters an interior space? Assuming that our space is not open to the outdoors, typically only a small amount of the daylight will be bounced back through the apertures to the outside. A very tiny amount of the daylight energy will break up molecules in our fabrics, artwork and other fragile materials. The remaining daylight energy will all be absorbed in interior surfaces and converted into heat. Much of the time, especially in large buildings, that heat is undesirable and will need to be pumped out of the space by a mechanical system, consuming energy. Our choice of glazing can have a major impact on how much heat gain results from daylight.

No glass is totally transparent – only a fraction of the light that hits it passes through. The good news is that readily available glass types admit daylight selectively. In other words, the fraction of visible light that is transmitted is often different from the fraction of total light energy that is transmitted. So if we choose our glazing well, we can admit less total energy (heat gain) for a given amount of visible light than we would if there were no glass, just an opening.

A useful way to evaluate glazing is to look at the ratio of visible light transmitted to heat gain transmitted. A good measure of the heat gain is the SHGC (solar heat gain coefficient). This information is readily available from major glass manufacturers, and some of them even calculate the ratio for us. Viracon, for example, calls this the LSG (light to solar gain ratio), and provides it in their glass data charts. For example, their data chart for 1-inch low-E insulating glass with argon fill shows that for clear glass (VE 1-2M) we can get a visible transmittance of 70% and an SHGC of 0.37, giving a very favorable ratio (LSG) of 1.90. So using this glass will cut the heat gain nearly in half for a given amount of admitted visible daylight. If we use glass tinted blue-green, the ratio can even be a bit higher, 2.01, however that improvement may not be worth the resulting coloration of the daylight.

An interesting way to think about this is that we can say we are using selective glazing to actually improve the energy quality of the daylight itself. The technical term for this quality is “efficacy”, which can be applied to artificial light sources as well as to daylight. Conventionally, the visible light energy is measured in lumens and the total (heat gain) energy is measured in watts. So efficacy is expressed as lumens per watt. The efficacy of outdoor “raw” daylight from sun and sky combined varies with sky condition and solar altitude, but generally runs around 100 to 120 lumens per watt. So for one watt of heat gain we get 100 to 120 lumens of visible light. Interestingly, this is very comparable to efficient electric light sources. With a high-efficiency T8 fluorescent lamp, for example, it will take just about 1 watt (including the energy to operate the ballast) to produce 100 lumens. Large HID lamps (metal-halide and high-pressure sodium) can produce more than 100 lumens for each input watt. So, other things being equal, raw daylight and electric light would result in the same heat gain to our space. But once we have passed the daylight through selective glazing, we can multiply its efficacy by the LSG ratio, so for the clear glass example it’s now around 190 to 230 lumens per watt. This cuts the daylight heat gain more or less in half. The daylight would now also create half the heat gain of an equal amount of electric light. The key word there is “equal”, since in practice daylight levels in a space will often be much higher than electric lighting levels, with resulting higher heat gain (see Daylighting Reduces Heat Gain – Pantheon Redesign?).

If a design mandates a certain amount of glazing, we can adjust the daylight levels by choosing different visible light transmissions. For example, the designer may want to choose a lower visible-transmission glass if the amount of glazing in the design creates daylight levels which are higher than necessary. Choosing glass with a high LSG ratio is still desirable in that case, but as the Viracon data shows, the ratio will be lower than with high-transmission glass. So that design will be paying a penalty in heat gain from daylight (and probably from the U-value of the extra glass also), compared to a design using a smaller area of high-transmission glass to accomplish the same daylight levels.

In some cases, a design could even benefit from different glasses at different apertures, for example, a high-transmission glass at a small clerestory and a lower-transmission glass at a large lower window. This approach should be used with caution – when all of the glass is the same, we don’t perceive the glass transmission very clearly. But when two different glasses are visible from the same viewpoint, the lower-transmission glass can look gloomy by comparison.

A Perspective on Daylight

June 11, 2012 / no comments

How much do you know about our sun and how it works? A recent episode of Nova, on my local PBS station, very effectively demonstrated my own limited knowledge on the object that accounts for over 99% of the total mass in the Solar System.

99%! That’s just staggering. Everything else out there: planets, comets, asteroids, and perhaps Stephen Hawking, make up the remaining <1%.

Think hard about all of that mass crammed into a near perfect sphere that is roughly 109 times the diameter of Earth and you start to get a sense of the amount of energy the sun contains. I’m certain most people understand that the sun is an immense fusion reactor: gravity compresses 620 million metric tons of hydrogen atoms together, fusing them into helium every second at temperatures around 5500 Celsius. But how is the light made?

During the fusion reaction, high-energy photons (gamma rays) are released and are ejected outwards. These photons which collide with hydrogen and helium atoms comprise the ultra-dense plasma core. The core is so dense that it takes photons anywhere between 10,000 and 170,000 years to ricochet out to the next layer, the radiative zone. Here, where the plasma is less dense, it only takes the photons about a month to make it to the convective layer. From there they travel through the photosphere and are free to propagate into space.

Once beyond the sun’s gravitational and magnetic influence, it only takes an average of 8 minutes and 19 seconds for the photons to reach Earth. Throughout each stage of their lengthy and tumultuous journey, the energy of the photons is greatly reduced, yet still provides tremendous heat and energy after traveling 97 million miles at 186,000 miles per second.

Justin Brown Lam Partners

So the next time you curse the sun as it blinds and roasts you or feel its warmth on your back or stop to observe it bathe a particularly bucolic scene with transcendent light, understand that that light might already be 100,000 years old. It’s actually a bit of a miracle when you think about it: too close to the sun, like Venus, and we’d be cooked, but too far away from it, like Mars, and we’d be frozen. We just happen to be on a pebble that’s the right distance from the sun’s fury and that’s about as incredible as it can get.

Photo credit: Justin Brown/Lam Partners

Mandatory Daylighting: Are You Ready?

May 14, 2012 / no comments

The long-awaited International Green Construction Code (IgCC) has been published. The International Code Council, the organization that produces building codes widely used in the United States, such as the IBC and IECC, produced the IgCC. Development began in 2009 with the American Institute of Architects on board as a sponsor. The International Association of Lighting Designers (IALD) was represented on the drafting committee and testified at all code development hearings. Along with our IALD colleagues, Lam Partners Principals Keith Yancey and I were intimately involved in the development of the electric and daylighting related provisions of the code. For more on green building codes, see my February 2010 article Will Green Building Codes Leave You Seeing Red?.

So now the question is, will the IgCC be widely adopted? One school of thought is that many municipalities are clamoring for a green building standard written in enforceable code language. The other asks why a municipality would add another very complex code to the enforcement responsibilities of their already overstretched inspectional services departments. Me? Well, I’m skeptical that IgCC will take off, especially considering the anti-regulatory tone in our political discourse these days. But don’t listen to me; I was surprised by the wildfire success of LEED.

What does this have to do with daylighting? Well, did you know that the IgCC has a mandatory provision requiring minimum daylighting of buildings? Surprise! We’re not talking about daylight responsive lighting controls to save energy; we’re talking about buildings having to be designed to ensure a minimum amount of daylight into the building. This is not a code requirement we are used to in the US.

So how does it work in IgCC? First, the requirement only applies to these building and space types:

Office, Higher Education, Labs

Retail (single-story and larger than 10,000 square-feet)

Schools

Manufacturing and Warehouse

Library reading areas, Transportation waiting areas, Exhibit halls, Athletic areas.

The IgCC says that in one-or-two story buildings, 50% of your floor area has to be daylighted and 25% in buildings three-floors and up. The trick is defining “daylighted”. IgCC does this with two options: a prescriptive method and a performance method. If your project is required to have a daylighted area larger than 25,000 square-feet, you must use the performance method.

Genzyme Lam Partners

Let’s look at the prescriptive method first. It defines your daylighted area based on the height and width of your windows and skylights. Then, assuming you have a sufficient daylighted area, you determine if you have a high enough “effective aperture” (EA). EA is just your window area multiplied by glass transmittance, divided by the daylighted area. The more window area you have and the higher transmission your glass is, the more daylight will enter. The minimum EA is given in a table and is based on the sky type for your location. There is also a nasty looking formula that lets you reduce the required daylighted area based on exterior shading obstructions, such as other buildings.

The performance method requires daylight computer modeling of the project. Simply put, the performance requirement says that you have to show that you will have at least 300lux and not more than 4500lux in the daylighted area. You show this under clear sky on the equinox for the either 9:00AM or 3:00PM.

Greenspace Lam Partners

Easy, right? Truthfully, both the prescriptive and performance requirements are more complicated than I have led you to believe and this will be especially true when applied to complex architecture. In many cases, designing a building to meet these requirements will require a daylighting design expert, and likely one with expertise in daylight computer modeling software. Those of us who deal with the LEED daylighting credit will find these daylighting requirements familiar, but if IgCC takes off we are going to have to pay attention to daylighting from the very beginning of the building design process. It’s one thing to say, “Hey, let’s see if we can get a LEED point.” With IgCC we’ll be saying, “If I don’t site, mass, and fenestrate my building properly, I’ll be in violation of code.”

Photo credit: Stephen M. Lee (1), Glenn Heinmiller/Lam Partners (2), Lam Partners (3)

Across the Pond

February 21, 2012 / no comments

The ‘Right to Light’ is an awesome piece of legislation in the UK. Unfortunately, it doesn’t exist in the US, and references to it have even been shot down in court cases. The UK law, in layman’s terms, says that an existing property has the right to enjoy and benefit from natural light. So, if a developer comes along and wants to build a bigger building near your property, one that reduces the amount of light your property receives, then they can’t build what they’re planning to. There’s often compromise, but the law ultimately favors people’s rights to natural light. Now, quantifying how much light one is entitled to may get a little more complicated in a legal dispute, but the principle is good – and surprisingly straightforward.

As energy codes continue to evolve, though (and I should note that the ‘Right to Light’ is a zoning law), they seem to be getting more and more complicated. Some code language has become so complex that there’s a concerted effort to simplify it, for better or worse. In principle, I would agree that simplification is in the design community’s best interest, but we shouldn’t set ourselves back just because the math gets too hard. Code language should be as simple as possible, but no simpler.

When considering daylighting and the individual’s right to light, how can we ensure that everyone in a building gets a piece of that daylight? Currently we do no such thing. We simply say, through energy codes, that if you have any daylight in a building, irrespective of building size or proportion, then you need to provide lighting controls to take advantage of the potential energy savings. When we discuss putting daylighting requirements into codes, any language that doesn’t deal with energy is basically forbidden. There’s no home in the current code structure for anything relating to quality. It’s good that we’re at least conscious of one of the benefits that daylighting provides, but perhaps we’re ignoring the most important reason for daylighting a building: we ignore the human factor.

If you wanted to build the most energy-efficient structure possible, you would build a box without windows. Glass is a worse insulator than a solid wall; it lets heat enter into and escape from the building envelope. Historically, we had very large windows because they provided the sole means of lighting the spaces within – great for lighting, but bad for heating and cooling. So, once we developed cheap electric lighting, we did away with all that glass (reference most buildings built in the 1970s). Sure, energy use went down, but so did happiness. I personally went to a middle school where you had no idea what the weather was doing outside until you left at the end of the day, and I certainly would not want to spend hours on end there now. So if no glass is the most efficient, why did we start adding windows again? People’s comfort!

There have been numerous studies over the years, and a little common sense, that told us we went too far in the 1970s. Have we done enough yet, though? If people’s happiness is the real reason for introducing daylight into a building, why do some people still sit near the core of a building, with no windows in sight? Why are buildings even designed to have such spaces? If we are willing to sacrifice energy efficiency to make people happier, why do we only do a half-assed job of providing daylight and views for everyone? Social inequality? Perhaps. LEED does a great job of promoting daylighting and views as an indoor environmental quality issue, but it’s still optional, as is the whole rating system. Maybe it’s finally time to focus on what daylighting our buildings is really about and put it into code language – simple code language.

Is it possible, then, to establish a personal right to light, and does it have any other benefits? Think about it: if we need to provide access to daylight and views for every regularly occupied space in a building, our buildings will naturally get thinner, which begets natural ventilation as well as more useful daylighting. We’ll also be able to seriously re-work our interior space planning so that there are no poor souls trapped behind the solid wall of private perimeter offices. Storage rooms and transient spaces get pushed in, and occupied space spreads outward. Ultimately, the more we can rely on naturally available resources like daylight, the more sustainable a structure becomes.

A building without windows will never be able to be inhabited without energy. Can we say, then, that every individual in a building, in their main workspace, must have access to daylight and views? From a code-language point of view, does this approach help to simplify how we regulate the use of daylighting? It’s a personal ‘right to light’ that just might help us save energy and drive future sustainable design innovation. Is it really that simple and intuitive?

Photo Credits: Paul Sableman (1), Miles Gehm (2), Joel Bedford (3)

Animation as a Lighting Design Tool

November 28, 2011 / no comments

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.

Many visualization techniques have been adopted from architectural conventions, but, as we all know, light and lighting present different and unique challenges to representation. Given that light is immaterial, dynamic, and ephemeral, designing with light means contending with aspects of time, intensity, and gradients. All these elements elude the static formats of drawings or diagrams. Especially when it comes to daylighting, giving a client a complete idea of lighting performance in a space is almost impossible without resorting to a stupefying series of image after image, calc after calc.

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.

Another reason we should be looking to new methods of representation is that clients are desirous of information about performance and appearance. As the time of day changes, the lighting and the performance change. Being able to visually convey these changes is extremely helpful to clients, and is a service that other consultants may not be able to provide. Animation may even help us to provide lighting design services in new ways and to fill new market needs.

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

Technology: Friend or Foe?

August 10, 2011 / no comments

Architects were the first lighting designers, and the first daylighting experts. The sun was once the only thing we had to illuminate the interiors of our architecture. We understood its character, its movement, its color and changeability. Until about seventy years ago or so, daylighting was still the primary source of energy used for illumination.

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Sure, we had candles, gas lanterns, and finally electric incandescent sources, but it wasn’t until the confluence of air conditioning and the fluorescent tube that we stopped designing our architecture to receive air and light from the great outdoors. Technology has given us wonderful inventions that make our lives on earth easier, happier, more comfortable, and more productive – but for a price. The energy needed to power all of this technology is being depleted. We can heat, cool, and light our buildings in any climate, in any architectural style, but only as long as we have enough fuel.

Indigenous or vernacular architecture was born from solving programmatic needs, using whatever natural resources were immediately available. With the advent of air conditioning in early 1900 and the invention of the fluorescent tube in 1938, we could virtually turn our backs to the outside world and create environments inside our buildings to our liking. As a result, we saw our architecture dramatically change. Office blocks became very large and, consequently, the resulting interior spaces were further removed from the perimeters of buildings. Interior spaces were almost entirely illuminated by electric lighting. It was easier and more economical to use fluorescent lighting than to design a building with more perimeter space that got its light from the sun.

As the years rolled on, we started to realize that these environments were not as desirable as the ones created by nature. Studies started revealing that productivity was suffering, that students’ test scores were in decline, and that people’s health was being sacrificed – all based on a separation from the sun, which helped us to produce vitamin D, set our circadian rhythms, and provided balance to our physical and psychological well-being.

It’s not all a doom-and-gloom story however. Fluorescent lighting is still, by far, the most popular way of illuminating the interiors of our buildings, but with new technologies it is even more efficient than ever before. Furthermore, fluorescence plays well with daylighting. Instead of replacing it, fluorescent and daylight coexist in very efficient and comfortable ways through advanced control technologies and thoughtful design. Dimmable ballasts, photocells, vacancy sensors, individually addressable equipment, and proper design techniques all make it easy to save energy and create wonderful luminous interior environments.

In addition, technology gives us design tools and simulation programs that allow us to forecast energy savings and previsualize our designs in unprecedented ways.

But, in order to take full advantage of these available technologies, architects must reclaim daylighting in their design domain. Unfortunately, the history of architecture in the last century is tragically described as a continual delamination between art and science, because architects passed these technologies into the hands of specialist consultants.

Reyner Banham, in his book The Architecture of the Well-Tempered Environment writes: “… the idea that architecture belongs in one place and technology in another is comparatively new in history, and its effect on architecture, which should be the most complete of the arts of mankind, has been crippling… the art of architecture became increasingly divorced from the practice of making and operating buildings.”

Today the profession is filled with competent and useful consultants and specialists, but the architect must use them, just as technology itself, in a manner that supports the art, and the human being living within that art. We must learn from history, but also embrace technology in ways we’ve never done before, to create beautifully daylit architecture, completely integrated to produce a true balance between art and science.

Photo Credits: Prasad Kholkute (1), Lam Partners (2-4)

Basic Sustainable Lighting Concepts: On Daylighting

June 27, 2011 / no comments

Part 2 of an ongoing series outlining design principles for sustainable lighting design: here are a few ideas regarding daylighting, to help navigate the greenwash.

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.

Shortchanging Daylight

June 13, 2011 / no comments

The reason for daylighting in buildings is to save energy, and so the value (“payback”) of that daylighting can be calculated by predicting and pricing the amount of energy saved. That’s a common line of thought which is easy to slip into, but it’s dead wrong.

Let’s look at a simple example of a new office building. A typical office worker’s space, including adjoining corridor, is about 110 square feet. Under today’s codes, we’re allowed 100 watts maximum to light that space. If it’s lighted 10 hours per day, 5 days per week, 52 weeks per year, that lighting will use 260 kilowatt-hours per year. At a high-end cost of $0.20 per kWh, that’s 52 bucks for electricity to light that space for a year. Let’s add another 30% for extra cooling cost due to that electricity, and we’ve got almost 68 bucks.

If our worker is the median American clerical worker, according to the US Bureau of Labor Statistics, his salary rate is about $14.40 per hour. Throw in 25% for statutory fringe benefits, and he’s costing his employer 18 bucks per hour.

So let’s say we have a wonderful daylighting design which uses absolutely no electricity to light our worker’s space. That 68 bucks per year equals less than four hours of his salary. That’s right: four hours.

If we have a wonderful daylighting design which improves their productivity by 1%, that saves their employer 375 dollars per year. A productivity improvement of just 1% creates a “payback” five-and-a-half times greater than the value of saving all of their lighting electricity. Run those numbers for a more highly-paid professional, legal, or scientific worker, and the productivity value will be much higher still.

To put it another way, if we calculate the payback of daylighting based only on electricity, we’re grossly underestimating the real payback; we’re shortchanging the daylighting. And that will lead to incorrect design decisions.

Some sophisticated building owners and managers know this. Savvy retailers know that their sales will go up with daylighting. Knowledgeable educators realize that the performance of students in daylighted classrooms will improve. Daylighting produces known health benefits.

We tend to think of these benefits as intangible, but they actually represent large numbers of tangible dollars on the bottom line. Like productivity, these factors aren’t intangible, they’re just hard to quantify.

By the way, the same calculation applies to good electric lighting as well: it may save a few dollars in electricity each year, but its value is vastly greater than that.