SPOTLIGHT REPORT Lighting Design for Health and Sustainability: A Guide for Architects Editors Paula Melton Editorial Director Brent Ehrlich Nadav Malin Alex Wilson James Wilson Peter Yost Graphic Design Julia Eva Bacon Cover Photo The Louisville Free Public Library South Central Regional Library Photo: Brandon Stengel About BuildingGreen BuildingGreen, Inc is an independent consultancy committed to providing accurate, unbiased, and timely guidance to help building industry professionals and policy makers improve the environmental performance of buildings and reduce their adverse impacts. We offer consulting, training, facilitation, and online resources to help our customers design and build from a whole-systems perspective. Our integrated design approach minimizes ecological impact and maximizes economic performance. Readers of this guide are eligible for continuing education credits from the AIA and GBCI. To claim your credits, take the quiz at www.buildinggreen.com/spotlight/lighting Published by BuildingGreen, Inc. 122 Birge St., Suite 30 Brattleboro, Vermont 05301 ©2018 BuildingGreen, Inc. All rights reserved. BuildingGreen Spotlight Report Lighting Design for Health and Sustainability: A Guide for Architects Lighting is an essential element in quality environments that support health and wellness while reducing energy use. By James Wilson Associate Editor The functionality of a building is largely dependent on the quality of its lighting. In order to safely and comfortably perform their tasks, occupants need lighting that provides adequate visibility without causing discomfort or distraction. But a focus on quality is also the key to achieving sustainable lighting. As Nancy Clanton, CEO of Clanton & Associates, advises, “Don’t design for energy savings; design well, and the result will be incredible energy savings.” By creating quality lighting conditions in their buildings, not only will project teams provide functional and comfortable spaces, but they’ll also achieve efficiency. And because the lighting in a space has such a significant impact on how people use that space and how they feel while in that space, it is critical to the human-health component of sustainability. Lighting affects not only the performance and productivity of occupants but also, more critically, their well-being. High-quality lighting, beyond providing basic comfort, can protect and promote health. The effects of lighting Like acoustic design, lighting design can have either positive or negative effects on people, especially in the spaces where many people spend a lot of time, like schools and offices. Research has shown positive correlations between quality Photo: Lara Swimmer lighting conditions and improved productivity as well as higher student test scores. Studies also suggest that quality lighting has positive impacts in healthcare settings—for example by improving the mood and perception of both staff and patients. Conversely, poor lighting conditions can hinder the way people work, learn, and heal by causing distraction, discomfort, and fatigue. The third floor reading space of the Madison Central Public Library, designed by MSR, is designed to receive an abundance of daylight. Getting the light right is crucial. As Bob Harris, FAIA, principal at Lake|Flato Architects put it, “If you’re not doing a good job with lighting, you’re not going to be doing a good job architecturally.” He explains that lighting is often treated as a secondary concern, taking a back seat to form-making. Too often, he argues, architecture is conceived of as an object to be viewed from a detached position rather than as a habitat to be experienced and lived in. Lighting Design for Health and Sustainability 2 BuildingGreen Spotlight Report And of course, in addition to affecting usability, comfort, and health, the way a building is lit also affects its environmental impact. What do we mean when we say sustainable lighting? And some LEDs also contain copper, which can create an environmental hazard if it accumulates in waterways. (LEDs, despite their long life, will eventually need to be replaced. They can be disposed of in regular landfills, as they are not currently regulated as hazardous waste.) A wide variety of sustainability issues intersect with architectural lighting. Though this report will largely focus on energy efficiency and occupant health and wellness, it is important to also consider the following related concerns when developing an integrated approach to sustainable lighting: • Light pollution—Project teams should avoid over-lighting, prevent light trespass, and consider potential impacts of lighting on the plant and animal life of the surrounding ecosystem, as well as on neighboring buildings, places, and communities. • Life-cycle impacts of lighting products—Lighting designers should work with manufacturers over time to reduce the embodied energy and carbon cost of fixtures, luminaires, and lamps. To help extend the life of the building and further reduce environmental impacts, when appropriate the lighting should be designed so that it can be easily retrofitted and adapted to align with future technology advances. (See Modular LED Lighting Enters the Mainstream and Product as a Service: Buying the Lumen, Not the Lightbulb.) • Chemicals of concern—Project teams should advocate and work with manufacturers to, over time, reduce the level of toxic materials in lighting products. For example, compact fluorescent lights, which contain highly toxic mercury, have to a large extent been replaced by LEDs, which do not contain mercury. However, sometimes LEDs are manufactured with high levels of lead and heavy metals. Photo: Mike Knell. License: CC BY-SA 2.0. High quality, low energy The information offered in this report generally revolves around lighting design that provides building occupants with the highest-quality illumination possible— providing comfortable and safe environments in which to complete their tasks— while using as little energy as possible. As part of an integrated approach to sustainable lighting design, project teams should avoid lighting strategies that contribute to light pollution. According to the Energy Information Administration, in 2010, lighting in U.S. commercial buildings required 297 billion kWh of electricity—about 22% of total commercial building electricity used in the nation. But technology has been rapidly evolving, and it’s becoming ever easier and more cost effective to drastically reduce the amount of energy consumed by lighting. In fact, LEDs have become so efficacious that additional gains in efficiency are small. The point has been reached where many in the lighting industry, who now see energy efficiency as a given, are turning most of their attention to the human-health component of sustainability and the ways that quality lighting can support it. Lighting Design for Health and Sustainability 3 BuildingGreen Spotlight Report Designing Sustainable Lighting In pursuit of quality sustainable lighting, a good place for any project team to start is with a refresher on the fundamentals of how light and human vision work. A good grasp of the relationship between light levels and what people actually see can go a long way toward helping the team make design decisions that will contribute to efficiency, health, and comfort. Understanding the difference and relationship between “measured light”—for example, the amount of lumens that a fixture emits—and “perceived light”—what a person actually sees—shifts the focus toward designing for effects of light and away from engineering for light levels. 1. Learn the basics of light As the members of a project team may all have different levels of knowledge and experience with lighting, it can be useful and efficient to devote some time, at the beginning of the design process, to getting everyone up to speed and on the same page. One option is to have the lighting designer give a brief educational presentation to the entire team. This would also allow the lighting designer to catch everyone up on the latest information about lighting techniques and technologies. (For example, a basic understanding of how LEDs work and how to evaluate the quality of different products can be very useful. See our previous feature article, LEDs: The Future Is Here.) The lighting industry is a rapidly evolving and increasingly complex field, and knowledge that was current only a few years ago may already be outdated. Brennan Schumacher, lighting designer and senior associate at Mazzetti + GBA, told BuildingGreen that on every project he works on, he gives a presentation to the entire project team early in the process. This allows him to educate them about his design perspective and approach to sustainable lighting design. “I think that adds a lot of value for the owner and the architects,” he said. “I get a lot of comments from the civil engineer, the landscape architect, or the mechanical LEARN THE LINGO: Lighting Literacy • Color Rendering Index (CRI): a metric that describes how faithfully a light source renders the true colors of objects and spaces (natural light has a perfect index of 100) • Correlated Color temperature (CCT): often shortened to “color temperature” or “Kelvin temperature,” it is used to described the color output of a light source— Common CCT values include: »» 2,700K: warm, slightly yellow tone, used to create relaxing environments »» 4,000K: neutral white tone, used to create “balanced” environments that allow for both relaxation and concentration »» 6,500K: cool, slightly blue tone, used to create environments that have an energizing effect • Glare: a vision impairment caused by either direct or reflected intense light; occurs whenever there is a high contrast between a light source and the surface or object being viewed • Luminous flux: the total output of light emitted by a light source, measured in lumens • Reflectance: a property of surfaces, expressed as the ratio of reflected light to incident light • TM-30-15: often shortened to TM-30, a method of evaluating and communicating the color rendering properties of a light source that includes several related measures and graphics, and which improves on the CRI method • Wall grazing: a lighting effect where a wall with an irregular, granular surface is illuminated creating both highlighted and shaded areas Image: J.C. Walker. License: CC BY-SA 3.0. It is useful for architects to know the definitions of different lighting metrics and how they relate. Lighting Design for Health and Sustainability • Wall washing: a lighting effect where a wall is illuminated so that surface irregularities are minimized, making the surface appear smoother 4 BuildingGreen Spotlight Report engineer about things that they have not thought about in regard to lighting.” Examples of some basic information that might be covered in such a presentation include the following. What light is, and how it interacts with building surfaces • Light consists of photons, invisible particles that are only perceived via their interaction with matter. This is what’s called light propagation—the reflection of light off of surfaces. What people see as light is the reflected color of surfaces. • Light reflects differently based on the color and structure of the surface at the microscopic scale. Smoother surfaces—like glazed tile—produce more direct reflections of light and are described as “specular.” Incident light— the light that falls on a surface—is reflected back at close to the same angle at which it strikes the surface. Matte surfaces—like unfinished wood or stone—are rougher and produce diffuse reflections of light because the incident light that hits it is scattered, meaning the light reflects off different portions of the material at different angles. The darker the color of the surface, the more light is absorbed and the less is reflected. How humans perceive and are affected by light • Humans have evolved over a long period to see the way they do, relying, for most of their existence, on the sun as their primary source of light. (Fire was discovered in the Stone Age and then combined with reflectors around 200 CE for use as a light source. Electric lighting only started to become common in the early twentieth century.) • The lenses, pupils, and irises of human eyes control how much light is transmitted to the rods and cones at the back of the eyes. The rods and cones respond by sending a signal through the optic nerve to the brain, which then communicates what is seen. Vision is not about the amount of light a person sees but about what that person perceives in the surrounding environment. • Humans have, at the backs of their eyes, photosensitive retinal ganglion cells that send different signals to the brain based on the light they are exposed to, impacting hormone production. This means that light affects a person’s physical, mental, and behavioral states. For example, when exposed to bright blue or white daylight, the body suppresses the production of melatonin, making a person alert and awake. When exposed to the warm red and yellow tones of the setting sun, the body increases production of melatonin, which makes a person relaxed and induces sleep. This light-and-dark cycle is known as circadian rhythm. The factors that affect visibility, which has little to do with light levels • the luminance, or reflected light, in the space that our eyes perceive • the contrast between different luminance values in a space • the size of the objects in a task being performed • the duration of time spent performing the task INSIGHT Brendon Levitt, associate at Loisos + Ubbelohde, described the importance of understanding the conceptual relationship between the task being performed in a space, the material in that space, and how that space is illuminated: “I think that’s either misunderstood or not well understood in a lot of cases. Understanding the room as light fixture is a critical piece. "We were in a project where we’d been going through this with the architect and talking about these corridors and how the lighting would work with it, and we had a strategy where we were going to illuminate the ceiling with an uplight in order to get a nice diffuse light throughout the corridors. "Then the interior designer came on and decided that they wanted to have a really dark walnut ceiling. And basically they completely absorbed all the light we were throwing up onto the ceiling and negated all the work that we did. So we had to redo the whole design based on that decision. "I don’t think the interior architect had any idea that that would affect the lighting. So it’s a combination of understanding what surfaces are being illuminated and what materials those are because in effect, by illuminating those materials, you’re creating another light fixture." The definitions of different lighting metrics and how they relate • Luminous flux, measured in lumens, refers to the light output of a fixture. • Illuminance, measured in lux or foot-candles, refers to the amount of light that falls on a surface. Lighting Design for Health and Sustainability 5 BuildingGreen Spotlight Report • Luminance, measured in candelas per square meter (cd/m2), refers to the amount of light reflected off of surfaces that our eyes perceive. (The candela is the base unit of luminous intensity, which is the power emitted by a light source in a particular direction.) Brendon Levitt, associate at Loisos + Ubbelohde, explained why it’s important to understand these basic concepts and the general relationship between light sources and architecture. “It really translates as, ‘What particular surface are you illuminating, for what purpose?’” he said. “I think if more architects could ask themselves that question, they’d get to the bottom of the lighting design a lot faster. They’d sort of answer a lot of questions for themselves about what they’re trying to accomplish. Because there always has to be a surface that’s illuminated.” 2. Work with a lighting design consultant Including a lighting design consultant on a project team is a great way to ensure that lighting concerns are integrated into the design. Although in the past architects relied on lighting designers mainly for help specifying fixtures, the lighting designer’s role has evolved over the past decade or so as architectural practice shifts toward more integrated approaches. Architects now often collaborate closely with lighting designers, starting in early phases of design, when massing decisions, which significantly affect opportunities for daylight, are being made. And, increasingly, project teams are looking for ways to integrate lighting considerations from the very beginning of the design process, rather than treating it as a kind of ornamentation that’s added on to a design. Great lighting design often appears seamless, and some may misinterpret that as meaning the task was effortless. The reality, however, is that achieving quality lighting often requires an extensive, iterative process and involves balancing a range of factors. The expertise of a lighting designer can go a long way toward making that process valuable and effective. But in order for this to happen, it’s important to treat lighting designers as collaborators rather than just having them run calculations or specify fixtures. A skilled lighting designer will be able to help blend together all the various, interdependent elements that affect the quality of lighting. INSIGHT Brendon Levitt, associate at Loisos + Ubbelohde, described the iterative process involved in lighting design: “You have to go through a few times. Very rarely is it possible to get it right on the first try. The reason for that is that there are a lot of variables here, and it’s not a determinative solution. You can’t say, ‘I need 62 foot-candles on these three surfaces and so the only solution is this right here.’ There’s about a million different variables between the aesthetics, the architectural intent, the task, the occupants’ expectation, the budget, the controls, the technology that’s available, the code restrictions, what your local jurisdiction is, how much light egress you get, what impact you have on other habitats, it goes on and on and on. And so all these different things mean that you’re going through this multiple times and you’re looking at it from multiple perspectives each time.” Photos: Timothy Brown (L), Andreas Praefcke (R) . License: CC BY 2.0. Louis Kahn, architect of the Kimbell Art Museum, worked with lighting designer Richard Kelly to develop the curved reflectors of the museum’s skylight system. The reflectors spread indirect natural light across the gallery ceilings while preventing direct sunlight, which would damage the paintings, from entering the space. Commissioned in 1966, the project used a computer expert to help determine the precise shape of the reflector’s curve—one of the earliest instances of designers using computer technology to model architectural components. Lighting Design for Health and Sustainability 6 BuildingGreen Spotlight Report For example, Susan Morgan, AIA, an architect at MSR, explained that her firm seeks to collaborate with lighting designers who have a facility with both the quantitative and the qualitative performance aspects of lighting because it allows for early conversations about how to achieve quality of place. “It really becomes a dialogue about where are the opportunities for lighting to help reinforce whatever it is,” she said. “If it’s in a large reading room in a library, it’s about being welcoming and comforting; if it’s about the design of an entry space, we want to present a strong sense of character and identity.” 3. Start early As is true with most aspects of high-performance design, it is crucial to start considering lighting early in the process. The best way to maximize the value offered by a lighting design consultant is to involve them from the beginning of the project. Clanton explained that, in terms of workflow, it is ideal for the lighting designer to be involved early to talk with the architect about their ideas for materials, colors, and different scenes. She described this process as a kind of walkthrough of the building with the architect to understand the vision for how the spaces should be experienced and to discuss how the lighting can support it. Additionally, as energy codes continue to evolve and as the requirements relating to lighting change, it can be helpful to have a lighting designer involved early to assess and explain how the code could potentially impact design decisions. In locations with more progressive energy codes, there may be more stringent rules that restrict the number of design solutions available. It’s important that the project team integrate these parameters into the discussion before spending too much time and money developing a design that will end up not being compliant. Image: Lake|Flato Architects Having a lighting design consultant involved from the early stages of design can also help the project team ensure that they are pursuing cost-effective solutions. An experienced lighting designer can help a project team assess factors like installation, programming, and maintenance to determine if a given lighting technology or strategy will be financially sustainable. A section diagram explaining the daylighting strategy used at the Indian Springs School, designed by Lake|Flato Architects. 4. Communicate effectively: a way to talk about what light can do When collaborating, it can be helpful for a lighting designer and an architect to have a common vocabulary to discuss how light can be used and to what effect. This contributes to a more informed dialogue about how the project’s lighting design impacts energy performance and occupant health and comfort, which in turn results in a more efficient and effective design process. Richard Kelly—who is generally recognized as the first modern lighting designer—came up with a set of categories of lighting effects in an effort to help the architects he worked with understand lighting design. Many contemporary lighting designers have adopted these terms, or variations of them, and find them to be Lighting Design for Health and Sustainability 7 BuildingGreen Spotlight Report effective when thinking together with project teams about light: • Play of brilliance—refers to lighting that sparkles, shimmers, or shines. An example would be a chandelier or sunlight reflecting on water. • Ambient luminescence—refers to large washes of light, generally coming from the ceiling or walls. It’s what most people mean when they say “ambient light.” • Focal glow—refers to lighting meant for a specific task in a space. An example would be spotlights on an artwork in a museum, or a task lamp on a desk in an office. Lighting designers and architects use these basic categories as layers that can be overlapped and combined in different ways to both adequately illuminate a space and produce visual interest, which is important for comfort. 5. Start with the sun The common view among lighting designers concerned with meeting sustainability goals of efficiency, health, and comfort, is that daylight is where all lighting design should start. After all, daylight is free, abundant, and has positive effects on human well-being. For example, exposure to daylight boosts the body's production of vitamin D, a healthy supply of which is believed to promote bone growth and prevent illnesses such as breast and colon cancers, multiple sclerosis, and depression. And because designing for daylight has implications for other major components—structure, mechanical system, landscape, materials, etc.—it is also the most logical place to start when taking an integrative design approach. “The first thing I want to know as the electric lighting designer is: where is the daylight coming from?” said Levitt. “I INSIGHT Brennan Schumacher, lighting designer and senior associate at Mazzetti + GBA described a successful project he worked on that demonstrates the value of a design approach that integrates lighting early in the process: “We did the Indian Springs school with Lake|Flato. It’s a little school outside Birmingham, Alabama—a series of classrooms and a couple offices. When they started the design, it was small classrooms and windows on both sides of the classrooms. They were analyzing this. … This is one where we were involved early on in the process, and we said, ‘What would you think if we popped the top and put a roof monitor up there?’ “They weren’t loving the idea right away, but they were open to it. So we ran a series of calcs and renderings kind of showing what this roof monitor could do. They loved it; they embraced it. They played with the form of that window a little bit, and we were analyzing the north and south side—really dialed it in. And now you can be in there and basically between the hours of 8:30 and 4 there’s not any direct sun that’s going to hit a student’s desk and yet the whole place is daylit. They would never need to have any electric lighting on during their hours of class. And I think that really is a singing success of integrated design and what it means to bring a lighting designer that’s willing to think about things in a more detailed or in a more sustainable way.” Photo: Casey Dunn At the Indian Springs School, designed by Lake|Flato Architects, a roof monitor over classrooms fills the space with natural light and prevents glare. The result is a comfortable space that’s conducive to learning. Lighting Design for Health and Sustainability 8 BuildingGreen Spotlight Report think all electric light needs to start with daylight. Electric light should be for the evening, and during the daytime, whenever and wherever possible, the electric light should be off.” Clanton told BuildingGreen that although some architects see her firm as dealing only with electric lighting, the first step in her practice is always to help design the daylighting. “If the daylighting is designed well, the electric lighting plays a very small role,” she said. “It’s not nearly as great as what it would be in a space without daylighting.” There are certain “rule of thumb” design strategies that can be applied to maximize the amount of usable daylight brought into a building, including: • south- and north-facing orientations • narrow floor plates • high ceilings • open sections Designing windows and rooms so that daylight is redirected to light the walls and the ceiling, and using lighter, more reflective materials on interior surfaces helps to distribute the daylight throughout the space. The darker the materials, the more light is absorbed, and the more electric lighting will potentially be needed to adequately illuminate the space. Project teams should also keep in mind that all electric lights produce heat—either through radiation or convection— and that this heat all eventually ends up as heat in a space. So in addition to requiring more electricity, excess electric light fixtures also raise energy use by increasing the cooling load of a space. Design for daylight can also often provide occupants with views to the outside, which, because it relaxes the visual system, contributes to health and comfort. Where direct views to the outdoors are not possible, reflecting dynamic, natural light into the space can also support a comforting and beneficial connection to nature. The more exposure people have to views and daylight, the better aligned their circadian rhythms are to the natural dark-light cycle. And research suggests that maintaining a consistent circadian rhythm may help improve overall health and prevent chronic diseases. Image: Qais Tabib. License: CC BY-SA 3.0. Designers can use a number of different techniques to bring daylight into interior spaces. But it’s critical to control the amount of daylight entering a space, for example by adding shading devices to windows. Extremely intense direct light and glare on task surfaces can cause severe discomfort and make a space unusable. Over-glazing and failure to properly control the amount of daylight entering a build- Lighting Design for Health and Sustainability 9 BuildingGreen Spotlight Report ing can also lead to excessive solar heat gain, causing thermal discomfort and increasing the building’s cooling load. (See Rethinking the All-Glass Building.) Steps should be taken to mitigate potential glare, especially during early hours of the day and in the evening, when the sun is low in the sky. If occupants draw their blinds to block glare, they often will leave them drawn, reducing the energy and health benefits that would otherwise be provided by incoming daylight. It’s also important to evaluate potential daylight strategies in relation to all sky conditions—clear, overcast, and partly cloudy—as any single design approach will perform differently under each. (For more information on designing for daylight, see Doing Daylighting Right.) 6. Integrate electric lighting Once the available daylight has been fully considered, integrated into the architec- tural design, and optimized for the space’s particular use, electric light should be blended in to augment the natural light and provide any additional illumination needed. In certain instances, it will not be possible to get much daylight into a space. One example is the low floors of buildings in dense urban settings. In such cases, it does not make sense to spend time and money to develop strategies based on daylight as a primary source. Basic early analysis tools can be used to study a project’s site and context and quickly determine whether daylight will be a feasible option. 7. Conduct early analysis Project teams can use early analysis tools (like Sefaira, DIVA-for-Rhino, and Ladybug Tools) to study the impact of the following characteristics, which will lead to better, more informed lighting design decisions: Image: Sefaira Architects can use early analysis tools, like Sefaira, to study the impact of design decisions like orientation and window placement. Lighting Design for Health and Sustainability 10 BuildingGreen Spotlight Report • building orientation • building form and footprint • placement and size of windows • placement, shape, and size of exterior solar shading • ceiling heights • section profiles Using early analysis tools to understand which spaces receive daylight—and how much daylight, and when—can inform programming, occupancy, and scheduling decisions. There are two common climate-based metrics that early analysis tools generate to describe a building’s relationship with daylight: • Spatial daylight autonomy (sDA) describes the percentage of a space that will receive sufficient daylight—defined as floor area that receives a minimum illumination level for a minimum percentage of annual occupied hours. For example, an area of floor may receive at least 300 lux for at least 50% of occupied hours. Designers can use this metric to help determine the right number and location of windows, the best ceiling heights, and the best floor plate depths. • Annual solar exposure (ASE) describes the percentage of a space that will receive too much direct sunlight (which can cause both visual and thermal discomfort), defined as at least 1,000 lux for at least 250 occupied hours per year. Note that ASE is not a direct measure of glare or thermal discomfort, but is only an indicator of possible glare or thermal comfort issues. Designers can use this metric during early analysis to determine which areas will receive too much direct sunlight and to evaluate the effectiveness of daylight control measures like shading devices or glazing with reduced visible transmittance. If an architect conducts early analysis to study site conditions and massing options, it can serve as a good starting point for discussions with the lighting designer about what’s possible regarding use of daylight and how electric light can be integrated to augment it. The lighting designer can also, if involved early enough, help substantiate or improve the assumptions made for early energy assessments. 8. Focus on quality In terms of creating lighting conditions that are conducive to human health, wellness, and comfort, the main objective is providing for visibility, which has everything to do with the quality of light in an environment and little to do with the actual quantity of light provided. An environment that feels bright and balanced, in which occupants can easily see what they need to see and where they are not distracted or fatigued by excess glare or contrast, is the baseline requirement for a quality lighting condition. Designers can increase the quality by adding visual interest. A main technique used to create comfortable and pleasurable environments is to focus on illuminating the building surfaces in a space—treating them as “light sources” that reflect light to provide visibility. It’s important then to pay attention to the reflectance values—which are based on material color—of the surfaces in the space. To avoid creating high levels of contrast, surfaces with drastically different reflectance values should not be placed together. Dark materials can be used to accent a room, but if too many of the surfaces are dark, it will require more light—and more electricity—to achieve an adequate level of brightness. And because humans mostly look at vertical surfaces like walls, these should be lighted first, and the ceiling next. Floors should be lighted last—as humans rare- Lighting Design for Health and Sustainability INSIGHT Susan T. Morgan, AIA, an architect at MSR, described how her firm uses early analysis tools to inform its understanding of a project’s lighting potential and support its collaborations with lighting designers: “It is now standard practice on our projects that we do a Sefaira daylight modeling study as we’re looking at preliminary massing to help us understand orientation, building massing, and geometry, and really maximizing the floor plate for daylight within the building. It’s been about a year-and-a-half since we put that into practice, and for us it has made a huge difference in us meeting our future and broader project goals from an energy standpoint. “I think both on an individual and a team level, it’s increased our literacy, and on the other hand it’s given us both tools and vocabulary to educate our clients about the effects that these early decisions have. And in fact, in many ways … it’s freed them up from a long-term commitment to electric lighting and the idea that … these spaces can be broadly daylit for the most part versus being broadly electric[ally] lit. And that really is a change in practice over the last few decades. “We usually have completed that before we sit down with a lighting designer because oftentimes we don’t bring them in until we’ve already done a little bit of a massing study and already started to understand the general footprint of the building on the site. But this becomes a tool for our dialogue about what decisions we’ve made to date and then what decisions lie ahead of us so that we can talk together about using the attributes of the site to really maximize daylighting on the project.” 11 BuildingGreen Spotlight Report ly look at floors. And where downlights are used to light the floor, it’s important to use fixtures that also direct some light up. This reduces the potential for glare caused by the contrast of a bright light source against a darker ceiling. In spaces where occupant focus and attention are important, like learning and work environments, it can help to provide a more simplified, uniform field of view. Because a very small portion of human vision is focused on the central area of the field of view, movement or glare at the periphery of the field of view can automatically catch the eye and divert attention away from tasks like reading. The eye will move constantly and involuntarily back and forth between peripheral distractions and central vision focused on a task, causing eye fatigue. 9. Layer light Designers can apply light as an architectural “material” to create effects that shape the spatial experience of an environment and affect the mood and perception of occupants. For example, lighting design that incorporates different layers of light creates an interesting, comfortable, and flexible environment. There are three standard layers or categories of light: • Ambient lighting is generally a uniform, base layer that provides general, overall illumination to a space. • Accent lighting, sometimes referred to as decorative lighting, is used to highlight points of interest in a space, like an artwork or architectural feature. • Task lighting provides illumination for the specific tasks that occupants perform in a space. Table and floor lamps, desk lamps, and bathroom vanity lighting are examples of task lighting. Photo: Andrea Calo Harris explained how great lighting design could even go beyond creating comfort to cause delight. “Often there are things that can happen with light that help create a sense of wonder and awe in certain ways,” he said. He added that, though this isn’t necessarily the primary goal, it is always very pleasant and appealing when the lighting, having been carefully crafted, adds a human touch to the architecture. Lighting Design for Health and Sustainability When designing the Austin Central Library, by Lake|Flato Architects, the project team focused on the concept of quality of light and set a goal of making the project one of the best daylit buildings in the world. 12 BuildingGreen Spotlight Report 10. Reduce ambient, provide task One common strategy for achieving greater efficiency is to provide a reduced level of ambient light in a space, and then provide users in that space the ability to focus higher levels of light on areas where tasks are being performed. An example would be individual task lamps on desks in an open office space. Lighting the walls and ceiling of a space to produce a lower ambient light level can also contribute to visual pleasure by making a space look alive and balanced. It also makes the space more flexible because the light is less tied to a certain set of tasks. 11. Leverage technology to protect health and increase comfort Light sources that provide a wider spectrum of light promote comfort because they increase the occupant’s ability to see objects in true color, the way they’re meant to be seen. One reason daylight is such a pleasant light source is that it provides the full spectrum of light, unlike most electric light sources (like incandescent and fluorescent lamps), which only provide portions of the spectrum. However, LED technology has now advanced to the point where high quality LEDs are able to provide the full spectrum of light, or close to it. Additionally, it’s now possible to produce LEDs that give the occupant the ability to control the color temperature of the light source, as well as the spectral distribution. This is important because it allows occupants to tune the electric lighting in their space, depending on the time of day, to create optimal conditions for circadian stimulus. For example, during the day, electric lights can be tuned to a cooler, neutral color temperature like 4,000 degrees Kelvin (4,000K), and in the evening they can be tuned to a warmer temperature like 2,700K. (The lower the color temperature of the light, the closer it is to the red end of the visible spectrum and the “warmer” the light feels.) This creates a more comfortable visual environment and protects the occupant from excessive levels of cool, blue light, which, as discussed earlier, can have a negative impact on the sleep cycle. 12. Specify high-quality LEDs Because of these advanced capabilities, LEDs have become the default source for electric lighting in almost every application—valued as much for their ability to create comfortable, pleasing light conditions as for their energy efficiency. (See Innovative LED Lighting from LightFair 2018 to read about some of the most cutting-edge products in the field.) However, manufacturing of LEDs is inconsistent, and not all LED products are created equal. Just because a light source Image: Phrood. License: Public domain. Different color temperatures are used to create environments with different effects. Warmer colors (lower temperatures) are used to create relaxing environments while cooler colors (higher temperatures) are used to create environments that have an energizing effect. In general, color temperatures below 3,200K are considered “warm” because they contain more reddish or yellowish tones. As the color temperature increases, they contain more blue and become increasingly “cool.” Lighting Design for Health and Sustainability INSIGHT Bob Harris, FAIA, principal at Lake|Flato Architects, described how a goal to maximize the quality of daylight at the Austin Civic Library was achieved and the impact it had on the users: “We really thought this goal would be a worthy goal for ourselves—to help create a sense of how we want to shape the architecture and the whole approach to it. We worked with lighting designers and natural daylighting experts and engineers and others to help reinforce those goals from the outset. We were able to do a lot of that visioning and goal setting upfront, and then put in the time and attention that was necessary to creating the right architectural responses to the lighting. And to bring both the natural and artificial lighting to the table to inform the building form, the footprint, everything about the way the program laid out on the site, and to help shape the right experience for the users. “It really was our central departure point for all those decisions—the idea of quality of light. It opened up this last year and has been overrun with citizens and people enjoying the library in new ways that they'd never had access to, at least in Austin, or I’d say probably in the state.” He explained that, although libraries are often thought of as quiet, private, darker spaces, the Austin Civic Library “was basically designed to be enlivened by light and to create a quality of the modern library that really functions more as a civic and social meeting grounds for people to come together around books but also around education and collaboration, and for meeting their neighbors and being together—a place that I think maybe libraries haven’t always been in the past.” 13 BuildingGreen Spotlight Report is an LED doesn’t automatically mean it’s a good light source. In short, the quality of an LED product depends on the supplier and the quality controls and root technologies that supplier uses. There are several different factors that are used to determine the quality of a light source. It can quickly get complicated, so having a lighting specialist on the team to help navigate the complexities is important. 13. Reduce power, time, or both When pursuing lighting energy-performance goals, it can be useful to think in terms of the equation: energy = power × time. The power variable has to do with the efficacy of the design (see definitions of efficacy below), and the time variable has to do with how long the light sources are on. Levitt explains, “If you can reduce either power or time, you’re going to reduce energy. If you can reduce both, you’re going to reduce a lot of energy. It’s also really interesting to note that if you can reduce either one a lot, then the other one matters a whole lot less. So if you can reduce your time, so that you only have lights on for a half hour a day, then how much power those use is much less important.” The following five scales of efficacy— which each affect the “power” variable of the equation—can serve as a guide to help project teams discuss and understand the various ways different lighting products and strategies impact the efficacy of the overall lighting design: • Lamp efficacy refers to the amount of light a lamp supplies for a given amount of electricity. It is measured in lumens per watt, or LPW. • Fixture or luminaire efficacy refers to how efficiently a luminaire directs the light offered by the lamp. For example, if the lamp offers a thousand lumens, how well does the luminaire act to direct those thousand lumens in a way that’s useful? A luminaire with black inner surfaces, which would absorb a large portion of the lumens offered by the lamp, would not be efficacious. • Layout efficacy refers to how well the fixtures in a space are located to properly illuminate surfaces and tasks. • Room efficacy refers to how well the characteristics of a space enhance the lighting. • Task efficacy refers to how well the illumination supports the task at hand. Ideally, only the surfaces that need to be illuminated for occupants to perform their tasks would be illuminated. 14. Provide controls In addition to optimizing the efficacy of the architectural space and specifying high-performance light sources, project teams can use controls to further reduce energy use. In fact, some lighting designers argue that the only way to get a lighting system to save energy, regardless of how efficient the light sources are, is to combine them with proper controls. Referring back to the “energy = power × time” equation, the purpose of using controls is to reduce the “time“ variable as much as possible. In short, the lights should either be dimmed or turned off whenever possible. Common types of controls used to reduce lighting energy use include: • photo sensors, which dim or turn lights on or off in response to the amount of daylight in a space INSIGHT Susan T. Morgan, AIA, an architect at MSR, described her experience working with a lighting designer on a 700seat multi-purpose auditorium for a library: “This is the kind of space where generally we have to control daylight because … it’s theater performances, it’s music performances—you don’t think of having to bring daylight into a space like that. But because the client wants to use it for other events, we started having very early conversations in pre-design about ‘Is there a way to bring daylight in?’ “And having a working charrette [with the lighting designer], we actually talked through the differences. Typically as architects we look at things from a form basis—so, ‘What if we put the windows on the side, what if we put the windows on the top, what is the shape, what is the aspect?’ And to bring Brennan [the lighting designer] into that conversation allowed us to really talk through not just, ‘What if we do it on this side?’ but what are some of the outcomes … in terms of quality of light—the color, and the hue, and the intensity? How easy or how difficult is it for us to manage daylighting on each of these facades? “So that allowed us … at a kind of deeper level to really kind of think through possibilities, but to also understand the outcomes a little more fully than you typically would during a pre-design phase, so it helps establish goals in a more specific and deliberate way than sometimes you would be able to.” • occupancy sensors, which dim or turn lights on or off in response to the presence of occupants in a space • time clocks, which dim or turn lights on or off based on an automated schedule that is programmed according Lighting Design for Health and Sustainability 14 BuildingGreen Spotlight Report to occupancy patterns or the daily sunrise and sunset times for the project’s geographical location • a demand-response system, which dims or turns lights on or off based on communications from the utility regarding increased demand on the grid It’s critical to design controls that are specific to the particular project. The project team should work with the owner to develop a clear, space-by-space control intent based on the use, occupancy, and daylight autonomy of each space. In private, single-occupant spaces, the controls might be pretty straightforward. But designing controls for public areas and shared, multi-occupant spaces can be complicated. Automatic controls, which may be required by code depending on project location, should ideally be designed and calibrated so that they are as seamless as possible. For example, when using occupancy sensors, project teams should specify dual-technology sensors that detect both ultrasonic and infrared signals. These operate with fewer issues because they require the absence of both types of signals before dimming or turning off lights, but require the presence of only one type to turn lights on. It’s also important to give occupants the ability to easily adjust or override the sensors remotely if they need to. Whether or not it makes sense to integrate lighting controls into the central building management system will depend on a variety of factors, such as project scale and typology, budget, users, and the facility Photo: Brandon Stengel staff’s familiarity and comfort with the system. For example, in projects with a specific and fixed set of uses, and a regular group of users and schedules, centralized control can streamline efficiency by reducing the number of people who need to engage with the system. However, in public buildings, with a varying set of uses and many different users occupying the building at irregular times, a more simplified, intuitive, decentralized system of controls is needed to provide for occupant comfort. The Louisville Free Public Library South Central Regional Library, designed by MSR, provides an example of how daylighting and artificial lighting can be balanced to create a quality environment. It can prove valuable to have the lighting system communicate with the building’s energy management system to produce detailed reports on the use and energy consumption of the lights. Facility management staff can use this feedback to monitor whether the lighting system is operating correctly or to locate the issue if something’s not working as expected. Lighting Design for Health and Sustainability 15 BuildingGreen Spotlight Report SIDEBAR: LED BASICS What Is an LED? Energy efficiency • LED (light emitting diode) lighting, or solid-state lighting (SSL), uses semiconductors (LED chips) to produce light as current flows across it. This produces energy, as photons of light, and also releases some heat. Using different semiconductor materials or engineering produces different colors of light. White light can also be created by using combinations of red, green, and blue LEDs. • LED lamps (sometimes called bulbs) are made up of the following components: an LED chip or chips, a heat management system (heat sink), electronics, and optics. • LED luminaires (light fixtures) include the LED lamp and components required to connect the lamp to the power supply, protect the lamp, and distribute the light. Optics • The light produced by an LED shines in one direction (unlike an incandescent lamp), so it has to be directed and diffused by optics for specific end uses. • Primary optics cover the LED chip to help improve light output. Phosphors that are critical for changing “blue” light to warmer reds and yellows are often added to these optics. • Secondary optics typically adjust the beam angle or create a more diffuse light. Drivers and dimmers • LEDs run on direct current (DC) and usually require a driver, or power supply, to convert alternating current (AC) from the utility to DC. Dimmers and building automation can also be integrated into the luminaire. In an LED replacement lamp, the driver and other electronics are contained in the base of the lamp. • Other LED luminaires use external drivers, either constant-current drivers that pair one light per driver, or constant-voltage drivers that connect to multiple lights connected in parallel. Drivers are critical to the efficacy and overall performance of an LED luminaire. • Energy efficiency in lighting is measured in the amount of light produced (lumens) per watt of energy consumed, or lumens per watt (lpw). • Luminous efficacy (sometimes called source efficacy or even LED efficacy) is the efficacy of just the LED chip before the optics, driver, and other electronics are added. Addition of the driver and other components lower the efficacy of the luminaire significantly. Manufacturers often tout the amazing efficacy of their chips, which can be confusing. Cree, for example, surpassed 300 lpw for one of its chips in 2014, but luminaires rarely reach 110 lpw. • Luminaire efficacy is a measure of the efficacy of the entire luminaire (or fixture), after the optics, driver, and other electronics are added. It is a measure of the amount of power a luminaire consumes per light output of the entire unit. LED luminaires with high color rendering index generally have lower efficacies. Color and Quality • LED color and quality are measured by the color rendering index (CRI) and the correlated color temperature (CCT). • CRI is a measure of how accurately a light source renders the colors of an object compared to a reference source. It is based on a scale from 0 to 100, with 100 being the most “accurate” color. An incandescent bulb has a CRI of 100, for example. LED CRIs are now above 80, with some reaching as high as 98. • CCT (measured in Kelvins) is based on the colors given off by an ideal metal heated up to the point of glowing. Most lighting falls in the 2,000K (orange-yellow candlelight) to 6,500K (blue midday sunlight) range. In general terms, color temperatures below 3,200K are considered “warm” because they contain more reddish or yellowish tones. As the color temperature increases, they contain more blue and become increasingly “cool.” Light quality can vary between brands, and there are no definitive color temperature cutoffs, but 3,200K to 4,500K are sometimes labeled neutral or cool white, and those above 4,500K are sometimes called cool white or daylight. • Dimming LEDs can be done in a number of ways, either through analog systems that vary the current or through digital systems using the international standard Digital Addressable Lighting Interface (DALI). • Drivers and dimmers have to be compatible with one another to maximize performance and reduce the chance of getting “hum” or flicker in the LEDs. Lighting Design for Health and Sustainability 16 BuildingGreen Spotlight Report 15. Integrate interior and exterior lighting 17. Conduct post-occupancy evaluations Especially on public projects, exterior lighting providing nighttime visibility is important for way-finding, security, and safety, but if it is not carefully designed or if too much light is provided, it can cause glare, light trespass, and habitat disruption. It’s always a good practice to visit projects after occupancy to verify that all systems are operating as designed and to address any issues that occupants may have. This is especially important when it comes to lighting systems, as they have a significant impact on usability and comfort. Although often exterior lighting is considered more as an afterthought, it can have a significant impact on the experience of the building. Architects should work together with the lighting designer, the landscape architect, and engineers to develop a holistic strategy in which interior and exterior lighting interact seamlessly and connect indoor and outdoor space. On larger buildings with more complex light systems, it’s important to go back after the building has been occupied for a few months and fine-tune the programming to match the actual use of the building as precisely as possible. 16. Commission the system Once construction is complete, it’s crucial to commission the lighting system to ensure that all the various components have been installed and programmed correctly. The more complex the lighting design—projects with multiple sophisticated control schemes—the more important commissioning becomes. The commissioning process can often uncover small issues that seem minor but can result in significant negative impacts on efficiency and occupant health and comfort. For example, an occupancy sensor may be installed too close to an air diffuser, which will prevent that sensor from dimming or turning off lights when it should. Or a sensor that was originally calibrated according to the surface reflectance values in a room may need to be re-calibrated if the materials in that room have been altered and affect reflectance. Some of the most common complaints related to lighting gathered during post-occupancy evaluations have to do with occupancy sensors. If the sensors are not operating correctly, occupants will often get frustrated and override them. It’s important then to resolve any issues there may be with the sensors to make sure that they continue to operate and contribute toward energy savings. It is also critical to work with the building management staff to make sure they understand how the controls and various features of the lighting system work. The more informed they are about how the system works, the more likely they are to engage with it to make sure it’s operating at peak performance and that maximum energy savings are being captured. Lighting Design for Health and Sustainability INSIGHT Brennan Schumacher, lighting designer and senior associate at Mazzetti + GBA, gave an example of how educating the building manager about how to engage with the lighting control system led to further energy savings: “We did the J. Craig Venter Institute a few years back.… We had all the dim levels topped out at 75% so none of the lights could come to full brightness, and we told the building manager, if you take that down 1% a day until you find people starting to say it doesn’t feel like we have enough light, and then ratchet it back up 3 or 4 points—they feel like they have great light, and you just saved 12% more energy. “The programming side—I can’t stress it enough—it’s really, really important, and for better or worse, it often comes down to the individual [who’s] actually onsite. … So we try to be onsite when the programming is happening, and I find that that adds a lot of value. We can answer all their questions right there on the spot, they hear more about our design intent, and I think they care more when the person [who] designed it is working with them rather than just sending them spreadsheets from 600 miles away.” 17 BuildingGreen Spotlight Report Continuing Education To receive continuing education credits, take this quiz online at www.buildinggreen.com/spotlight/lighting. 1 AIA LU|HSW, 1 GBCI CE hour INSTRUCTIONS: efficiency. If you purchased this report, or if you are a BuildingGreen Premium member, you can get continuing education credits by successfully completing this quiz on our website. Learning Objectives For BuildingGreen to automatically report your CEUs, you will need to add your AIA and/or GBCI identification info to your profile, at www.buildinggreen.com/user. Description What do we mean when we say sustainable lighting? In this course BuildingGreen takes a closer look at lighting as an essential element in quality environments that support health and wellness while reducing energy use. The functionality of a building is largely dependent on the quality of its lighting, which is often treated as a secondary concern, taking a back seat to form-making. Lighting design can have either positive or negative effects on people, especially in the spaces where many people spend a lot of time. In order to safely and comfortably perform their tasks, occupants need lighting that provides adequate visibility without causing discomfort or distraction. Take a look with BuildingGreen at how quality lighting conditions in buildings not only provide functional and comfortable spaces, but can also achieve Upon completion of this course, participants will be able to: 1. Describe how high-quality lighting design dovetails with sustainability by improving energy efficiency and supporting occupant health and well-being. ® 2. Explain the sustainability benefits of daylighting, including increased energy efficiency and wellness, along with the drawbacks of poor daylighting design—such as excessive glare and solar heat gain, which can reduce energy efficiency and cause occupant discomfort. 3. Define basic lighting terms, such as “play of brilliance,” “spatial daylight autonomy,” and “color rendering index,” along with the relevance of such lighting terms to improved efficiency and occupant wellness. 4. Understand the expanding role of high-quality LEDs in sustainable lighting design, and demonstrate proficiency with the vocabulary of LEDs relating to efficacy and light quality. Lighting Design for Health and Sustainability 18 QUIZ QUESTIONS 1. I n order to safely and comfortably perform their tasks, occupants need lighting that provides adequate visibility without causing ____. a. b. c. d. Thermal mirages Faintness Discomfort or distraction Tint and texture 2. High-quality ____, beyond providing basic comfort, can protect and promote health. a. b. c. d. Lighting Air Stilts Dressings 3. L ike acoustic design, ____ can have either positive or negative effects on people, especially in the spaces where many people spend a lot of time, like schools and offices. a. b. c. d. Aperture Lighting design Window treatments Oranges 4. S tudies have shown that in healthcare settings, poor lighting conditions can hinder the way people work, learn, and heal by causing ____. (Select all that apply) a. b. c. d. Distraction Discomfort Fatigue All of the above a. b. c. d. a. b. c. d. Waterways The air Outdoor shoes Pets 7. According to the Energy Information Administration, in 2010, lighting in U.S. commercial buildings required ____ kWh of electricity—about 22% of total commercial building electricity use in the nation. a. b. c. d. 156 trillion 297 billion 758 million 124 million 8. Play of brilliance refers to lighting that sparkles, shimmers, or shines, such as chandelier or sunlight reflecting on ____ . a. b. c. d. Water Windows Walls Wellies 9. The three standard layers of light that creates an interesting, comfortable, and flexible environment are task, accent, and ambient lighting. a. True b. False 5. P roject teams should avoid ____ by not overlighting, prevent light trespass, and consider potential impacts of lighting on the plant and animal life of the surrounding ecosystem as well as on neighboring buildings, places, and communities. 6. Some chemicals of concern in lighting products are compact fluorescent lights, which contain highly toxic mercury and LEDs that contain copper which can create an environmental hazard if it accumulates in ____. Sound barriers Integrated complexities Tight hamstrings Light pollution 10. Common types of controls used to reduce lighting energy use include: (Select all that apply) a. b. c. d. e. Photo sensors Occupancy sensors Time clocks Demand-response system All of the above TAKE THE OFFICIAL QUIZ www.buildinggreen.com/spotlight/lighting