Cover image: Kitchen photo: Kitchen design by Joseph A. Giorgi, Jr., CKD; codesigners Erin Paige Pitts and Dru Hinterleiter. Photo by Peter Leach.
Bathroom photo: Bathroom design by Paul Knutson. Photo by Troy Thies
Cover design: Wiley
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The National Kitchen & Bath Association recognizes, with gratitude, the following companies whose generous contribution supported the development of Kitchen & Bath Lighting.
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The National Kitchen & Bath Association (NKBA) is the only nonprofit trade association dedicated exclusively to the kitchen and bath industry and is the leading source of information and education for professionals in the field. Fifty years after its inception, the NKBA has a membership of more than 60,000 and is the proud owner of the Kitchen & Bath Industry Show (KBIS).
The NKBA's mission is to enhance member success and excellence, promote professionalism and ethical business practices, and provide leadership and direction for the kitchen and bath industry worldwide.
The NKBA has pioneered innovative industry research, developed effective business management tools, and set groundbreaking design standards for safe, functional, and comfortable kitchens and baths.
Recognized as the kitchen and bath industry's leader in learning and professional development, the NKBA offers professionals of all levels of experience essential reference materials, conferences, virtual learning opportunities, marketing assistance, design competitions, consumer referrals, internships, and opportunities to serve in leadership positions.
The NKBA's internationally recognized certification program provides professionals the opportunity to demonstrate knowledge and excellence as Associate Kitchen & Bath Designer (AKBD), Certified Kitchen Designer (CKD), Certified Bath Designer (CBD), and Certified Master Kitchen & Bath Designer (CMKBD).
For students entering the industry, the NKBA offers Accredited and Supported Programs, which provide NKBA-approved curriculum at more than 60 learning institutions throughout the United States and Canada.
For consumers, the NKBA showcases award-winning designs and provides information on remodeling, green design, safety, and more at NKBA.org. The NKBA Pro Search tool helps consumers locate kitchen and bath professionals in their area.
The NKBA offers membership in 11 different industry segments: dealers, designers, manufacturers and suppliers, multi-branch retailers and home centers, decorative plumbing and hardware, manufacturer's representatives, builders and remodelers, installers, fabricators, cabinet shops, and distributors. For more information, visit NKBA.org.
Welcome to Kitchen & Bath Lighting. As vision is our most significant sense, so lighting is critical to our perception of the world around us and to our effective performance, attractive appearance, and healthy emotions.
Lighting is one of the elements of design. Some might say it is the most important as without it we would not be able to see the other elements. It can enhance the look and feel of a space or detract from it if done incorrectly.
Kitchens and baths represent the residential spaces where lighting is used most often and most critically. The principles of lighting kitchen tasks and social areas often can be applied to other work and living spaces, while understanding how to light at a bathroom vanity can inform attractive lighting for conversations throughout the home.
This book is intended both to provide a sound basis in the fundamentals of lighting and to guide in the application of lighting to the two most critical task spaces of the home. We approach kitchen and bath lighting in several broad categories familiar to designers.
In chapters 1 through 6 we focus on the fundamentals of lighting and discuss how we see materials, spaces, and each other; how to calibrate lighting for different tasks; and how to modulate lighting as we age.
Chapters 7 and 8 explore the importance of sustainable lighting and daylighting.
In Chapter 9 we cover schematic design by presenting a visual vocabulary for speaking about lighting and applying these ideas to conceptualizing lighting for kitchen and bath spaces.
Chapters 10 through 12 provide important information on choosing and comparing light sources and fixtures and in Chapter 13 lighting controls are discussed.
Chapter 14 explains the many aspects of design development including the selection of light sources, luminaires, and controls and the processes involved in locating equipment, calculating illumination, and addressing code compliance.
Chapter 15 covers the important topics of documenting the lighting design and communicating the design to the construction team and finally, in Chapter 16 we explain the process and critical issues involved with getting lighting built in the real world.
Three critical issues stand out today: changing lighting technology, sustainable design approaches, and lighting for older eyes.
If this book had been written 50 years ago, the lighting principles—how we see and how to arrange lighting—would have been largely the same. But, of course, technology in the twentieth century would have been significantly different. Indeed, if the book had been written even just a few years ago, light sources, luminaires, and controls would be considerably different.
Most notably, LEDs—light-emitting diodes—are rapidly changing what we light with, how light colors what we see, how it looks in our homes, and how it affects the natural environment. At the same time, control over lighting has become both more convenient and more sophisticated. The combination of digital light sources (LEDs) and digital controls promises a future of lighting that adapts readily to different needs, uses, and preferences. With the majority of the population working and playing on video displays of some kind, the way we light spaces has changed completely as well.
Around the globe, developing economies are trying to meet the fast-rising expectations of their populations. A peaceful world will need sustainable lighting—lighting that meets the human needs of today with the least impact on energy and other natural resources so as not to compromise future generations.
Young people often can work without any electric lighting. As people age, we typically use lighting more often and in greater quantity. This progression is inevitable, at least for most of us. And for much of the developing world, it is true not only for individuals but for the population as a whole. Providing for the range of needs required by residents of varying ages is a critical challenge for lighting design.
We pick up the strands of these issues throughout the book. Woven together, they help us to think about lighting holistically: who the lighting is for, what their needs and desires are, and how we can use design and technology to meet their needs and even exceed their expectations.
Dan Blitzer
I feel very grateful to have the opportunity to share my knowledge of and enthusiasm for the interior design industry, specifically kitchen and bath design. The National Kitchen & Bath Association's commitment to education in this area of expertise has been incredible. Johanna Baars, Publications Specialist, Lisa H-Millard, Course Developer, and Debby Mayberry, Learning and Development Implementation Specialist, have been instrumental in providing support and encouragement to me throughout this process.
The team at my firm and my family at home have also been supportive and excited about this new book added to the series. Thanks to all. I give my best to future kitchen and bath designers. I hope you enjoy your journey as much as I have enjoyed mine so far.
Tammy MacKay
The NKBA gratefully acknowledges the following peer reviewers of this book:
Light, how it enables us to see, and lighting terminology together provide the necessary foundation for understanding lighting. In this chapter, we begin to consider these fundamental concepts. In subsequent chapters, we investigate lighting fundamentals in more detail.
Light is the energy that enables us to see. Technically, light is part of the broad spectrum of electromagnetic energy and is defined as visually evaluated radiant energy (see Figure 1.1).
Figure 1.1 Light in the electromagnetic spectrum
Courtesy of Peter Hermes Furian
As you may recall from classes in physics, light exhibits the properties of both waves and particles. As a radiating wave, light can be described by its wavelength, which ranges from about 380 to 760 nanometers (billionths of a meter), the limits of human visual sensitivity. In the next chapter, we explain that describing light by its wavelength helps us to understand the interaction of light and materials. Later, when we look at light sources, we encounter the particle nature of light—especially in understanding LED technology.
A few observations:
Figure 1.2 Transparent, translucent, opaque
Figure 1.3 Reflection, refraction, scattering
Although vision is not our oldest sense (we touch before we see), it dominates our perception. Basically, human vision is simple: Light interacts with objects; travels to, then enters, our eyes, where it is transformed into electrical signals; these signals travel neurological pathways to reach our brain, where they are interpreted into visual perception. Another way to express this basic process is by its four essential components (see Figure 1.4):
Figure 1.4 Light source, object, eye, brain
We know a great deal about the physics of light and how it interacts with objects. We also know a great deal about the physiology of the human eye, how it receives light and creates neurological connections. We know considerably less about the complexities of how our neurological signals are combined with memory and interpretive algorithms into dynamic, three-dimensional perception.
Pause for a moment to consider the following. The signals received on the two-dimensional “screen” of our retina are fundamentally ambiguous: Is the retinal image a small object close by or a large one at a distance? Yet, apart from some notable optical illusions, we see the world unambiguously. This is only the most obvious example of our remarkable powers of visual perception. Good lighting can enhance these powers, while poorly designed lighting just makes seeing that much harder.
Our visual system compares the incoming signals, searching for differences in light intensity and color. It does not measure or quantify them in technical photometric (light measurement) terms. Instead, the essence of how we see is the contrast between dark and light or among various colors.
Later in this chapter, we discuss how we measure light and all the technical terms associated with these quantities. When we do this, we also discuss the problems created by measurements that do not adequately represent perception.
Remarkably, our visual system operates effectively in a range of about 20,000:1, that is, from a bright sunny day to a starlit night. We manage to see in such a broad range by adjusting both the amount of light reaching the eye and the sensitivity of the photoreceptors. In darkened conditions, our pupils dilate to admit more light, and the eye's chemistry becomes more sensitive to the limited amount of light available. In bright conditions, in contrast, pupils contract, and sensitivity diminishes to avoid overload.
Adaptation takes time; it takes as much as 30 minutes to adapt to darkened conditions. Adapting to bright conditions takes less time. However, rushing the process (e.g., by emerging from a darkened theater to a bright afternoon) can prove painful.
Indoors, your vision adapts as you move from darker spaces to brighter ones and back again. Shifting your gaze from a brightly lighted task to a much darker surface also involves adaptation. Frequent and extreme adaptation can cause eye fatigue and discomfort.
The physiology of the eye helps us understand lighting—and how to design it for different applications and users of different ages and visual impairments. Take a moment to study the diagram of the human eye in Figure 1.5.
Figure 1.5 Diagram of the eye
We have already discussed an important function for the pupil: regulating the quantity of light received. The rays of light ultimately enter the eye through a lens that receives them onto the retina, which contains the photo sensors and connective neural networks that translate incident light into neurological signals. When the lens malfunctions (focuses improperly or simply loses clarity), vision is impaired.
Inside the eye, light travels through liquid from the lens to the retina. Impurities can disrupt light's passage and, with it, vision. Degradation in the retina (macular degeneration is one important example) also diminishes vision.
The retina contains three basic types of photoreceptors:
We return to the photoreceptors in more detail when we discuss color in Chapter 2, “Seeing Materials” (and to nonvisual photoreceptors when we discuss lighting for aging eyes).
Finally, notice how an overhanging brow protects the entire eye, limiting the glare from overhead sources of bright light—to some degree at least.
Light emanates from a source and (some of it) arrives at an object. Light then leaves that object (reflects off or passes through it) and travels to the next object, and so on. Thus, if we want to measure light, we need to do so at the various points in its travel.
Let's start with the source itself. A lumen is a unit of measure for quantifying the amount of light energy emitted by a light source. A typical light source in your dining room might emit 800 lumens, one in the laundry room might emit 2500 lumens, and one in the streetlight outside might emit 16,000 lumens.
LUMEN VALUES FOR VARIOUS LIGHT SOURCES
| Light Source | Luminous Flux (lumens) | Typical Use |
| LED light bulb (12W) | 800 lumens | Table fixture |
| Halogen flood (60W) | 1100 lumens | Retail display |
| Linear fluorescent (28W) | 2500 lumens | Office lighting |
| High-pressure sodium (150W) | 16,000 lumens | Street lighting |
Since light can flow in any direction, luminous flux (lumens) can be measured anywhere. The most common measurements are made at lamps (light sources) and fixtures (technically, luminaires, which are fixtures with light sources in them). You will find lumen ratings in lamp and luminaire catalogs, specification sheets, and websites, as well as on many lamp packages (see Figure 1.6).
Figure 1.6 Lamp package label
Courtesy of American Lighting Association
If the flow of light (lumens) is concentrated into a tight beam, we say that it is intense (strong in that single direction). This is called luminous intensity and is measured in candela. Light sources and luminaires with distinct beams of light (whether concentrated as spots or diffused as floods) typically are measured in both lumens and candela.
With light sources that direct light into beams, candela measurements will vary significantly according to the angle at which the intensity is measured. With light sources that distribute light more or less evenly in all directions, the candela measurements will be very similar.
The word “intensity” has the common meaning of “strength.” In lighting, luminous intensity has the technical meaning of “strength in a specific direction.” We use the term “lumens” to measure the total flow of light, regardless of direction.
When light falls on a surface, it is called illuminance. Technically, we measure the density of the illuminance that is the quantity of lumens falling on a surface. One lumen per square foot equals 1 footcandle. This is an imperial measurement. Its metric equivalent is lux. One lumen per square meter equals 1 lux. The conversion of footcandle (FC) to lux is 1 footcandle = 10.764 lux.
If 100 lumens fall on 1 square foot of countertop, we would measure that as 100 footcandles. If those lumens were spread over 10 square feet, we would measure it as 10 footcandles. The same comparison can be made for lux. If 100 lumens fall on 1 square meter of countertop, we would measure that at 100 lux.
Illuminance is measured with a luminance meter (also called an illuminance meter). The Illuminating Engineering Society has established recommended illuminance targets (in footcandles) for almost every room or setting.
So far, none of our measurements represents what we see. Lumens and candela measure light at the source; footcandles (lux) measure light falling on the surface of an object. We see when light reflects from (or passes through) an object and reaches our eye. We can measure the amount of light detected by the eye from a surface at a particular angle; this is called luminance.
In practice, luminance measurements are cumbersome and costly, and so are rarely used in everyday design. Instead, we use the term brightness to express our perception of light, including the many non-quantified factors that influence our visual process.
It is worth emphasizing that most of what we measure in lighting—the lumens flowing from a light source, the candela at the center of a beam of light, the footcandles falling on a surface—do not represent what we see when we look at a room, a task, or a person.
Our perception depends on the materials we are lighting, what we see around the space, how we are adapted to the brightness of the space, the color of the light, and other factors, which we discuss in later chapters.
What good are these measurements then? As you will learn, we apply the measurements of lighting to predict how well lighting will meet our objectives. By themselves, these measurements are of little use. But together with an understanding of how light interacts with materials, people, and task demands, they can help us judge how to provide appropriate lighting.
Light is the energy that enables us to see. It travels invisibly, and when it encounters a material, it reflects, refracts, or is absorbed by it. We see when light reaches the photoreceptors in our eyes, stimulating signals that are interpreted by our brain. Our visual system responds to contrast (rather than absolute levels of light) and adapts to variations in ambient brightness. We measure light in three widely used measurements: luminous flux (lumens), which refers to the flow of light; intensity (candela), which refers to the strength of light in a specific direction; and illuminance (footcandle/lux), which refers to the amount of light falling on a surface.
What are the four elements in human vision? (See “Vision,” page 2)
What is the role of contrast in vision? (See “Contrast,” page 4)
What is the role of adaptation in vision? (See “Adaptation,” page 4)
In what part of the eye are the photoreceptors located? (See “Physiology of the Eye,”page 5)
What are the units of measure for luminous flux, intensity, and illuminance? (See “Footcandle/Lux,” page 7)