No building strategy intertwines the disciplines of architecture and lighting as daylighting design does. Drawing on core principles of siting, solar orientation, and environmental awareness, daylighting gives basic form to architecture through illumination. “Daylight is the primary source for architecture,” says Hayden McKay, AIA, a New York–based principal at HLB Lighting Design and leader of the firm’s daylighting and sustainable design studio. “It has been over time and it still remains the first thing that should be considered in creating architectural forms and fenestration orientation.”
However, underlying any discussion of daylighting and architecture is the former’s ability to reduce a building’s energy consumption and improve its overall performance. This benefit emerged in the late 20th century, which saw the emergence of “energy-conscious architecture,” a phrase that describes a generation of building projects that incorporated daylighting design as the driver for energy savings and the analytical tools used to measure their performance, says Mark DeKay, an architect and professor at the University of Tennessee, Knoxville’s College of Architecture + Design, and co-author of Sun, Wind, and Light: Architectural Design Strategies (John Wiley & Sons, 3rd ed., 2014).
Since that time, energy efficiency and sustainable design have secured their place in the architectural lexicon with the introduction of stringent energy and building codes and marketable sustainable design metrics, such as the ratings of the U.S. Green Building Council’s (USGBC's) LEED system.
Critically, changes were also occurring on the lighting front. The switch to LEDs and the phaseout of incandescent sources, as mandated by the Energy Independence and Security Act of 2007, have forever changed the way in which energy performance arguments are made, particularly when specifying whole categories of light sources and associated fixtures. Simply put, lighting’s analog-to-digital paradigm shift has upended the industry.
Accordingly, the case for daylighting design must transform to one that elevates its potential benefits not in energy consumption, but rather in occupant health and well-being.
Ending the Energy Argument
LED luminaires are overwhelmingly more efficient than their counterparts that utilize legacy sources such as incandescent, halogen, metal halide, or fluorescent lamps. An LED downlight today can be expected to use between 9W and 24W, while its legacy predecessor could consume between 13W and 50W—essentially double the wattage.
Multiply the savings of switching a single fixture to LED by all the luminaires on a project—and tack on the fact that designers must comply with some of the strictest building, energy, and lighting codes, such as California’s Title 24—and the result is high-performance, energy-conscious lighting design. “Because LEDs are so efficient, there’s very little energy to be saved with electric lighting and daylight harvesting controls,” McKay explains.
Gregg Ander, FAIA, former chief architect of Southern California Edison and the author of Daylighting Performance and Design (John Wiley & Sons, 2nd ed., 2003), concurs: “The energy densities are much less now—below 0.5W a square foot in many cases as opposed to 3W a square foot as in previous decades.” With states such as California, Massachusetts, Texas, Minnesota, and Hawaii leading the way on what he calls the “decarbonizing” of their economies, “you have this massive transformational market shift going on driven by executive orders, legislation, regulation, codes, and a whole bunch of things that’s leading to a perfect storm.”
In this case, the perfect storm is a good thing: increased building efficiency, advanced automation of building controls, and a demand for people who can develop these systems and associated products. But where does this leave the argument for daylighting design?
Elevating Health and Well-Being
As the impact of LEDs and daylighting on increased energy efficiency veers toward self-obsolescence, interest in the lighting mediums’ roles in occupant performance is ramping up. Research correlating the presence of daylighting in work and school environments to increased occupant productivity began emerging in the 1980s and 1990s. A number of studies found that better employee performance led to fewer sick days, which then resulted in lower business operating costs. Similarly, studies such as those conducted by architect and lighting specialist Lisa Heschong and her firm, the Heschong Mahone Group (now part of the TRC Companies), found that students with greater exposure to daylight recorded better test results and fewer absences.
More recently, the argument for daylighting’s ability to influence health has received a boost from advancements in technology. Designers can now adjust or tune electric light to create a specific color temperature range for a designated time of day or activity level in a manner that draws on daylight as the base layer of illumination. When the lighting of a space is calibrated to work with our biological needs and circadian cycle—which, of course, daylighting innately does—the design represents a stronger understanding of how light and architecture can coordinate and how occupants interact with their environment. This human-centric approach to lighting has emerged as the strongest case for incorporating daylighting design strategies in buildings today and in the future.
The ability to integrate color-tunable fixtures into a daylighting strategy also addresses concerns about sacrifices to the quality of light that had emerged in the wake of the incandescent phaseout, when building codes pushed lighting power densities to near zero levels, and a crop of spaces with an overall poor quality of illumination emerged. Daylighting projects today “have to make the case on lighting quality and experience,” says Matt Franks, associate principal and senior lighting consultant in the New York office of Arup.
The global firm has installed a full circadian-light system in its Boston office that emulates the sun’s changing hues from dawn to dusk. The electric lighting follows a color temperature curve from 3000K (warm) to 5000K (cool) and then back to 3000K over the course of the workday. The system adjusts over the year to correspond to longer daylight hours in the spring and the summer. Arup is working on similar systems in its Chicago and San Francisco locations, and exploring a system for its Seattle office, says New York–based principal Brian Stacy, who also leads the firm’s lighting group in North America. “Some are full circadian systems, some are tunable systems; we’re playing around with what that means because there is a distinction.” Most tunable systems focus on color temperature without factoring in illuminance and glare metrics, he notes. “The key is to meet target illuminance (brightness) levels at the work surface and vertically at the eye.”
And similar to how energy performance attracted more public attention with programs like the USGBC’s LEED rating system, circadian lighting is getting help from the WELL Building Standard, which offers guidelines and metrics for creating healthy living and working environments. “LEED is focused on buildings,” says Matthew Tanteri, associate principal and daylighting practice leader in HLB’s office in Austin, Texas. “WELL has its focus on the body and the person: It’s human-centric.”
While daylighting might find new relevance in a light and health context rather than as a means for energy savings, its place in architectural design remains uncertain. One longstanding question is where this field sits in the realm of architecture and lighting. Practitioners remain firmly rooted in either the architecture or the lighting camp and few events, if any, work to foster interdisciplinary communication.
Also out of reach is agreement on universal performance metrics and technical vocabulary, even among daylighting practitioners themselves. In his 2008 Architectural Lighting article “Daylight Dialect,” Kevin Van Den Wymelenberg, Assoc. AIA, director of the Institute for Health in the Built Environment at University of Oregon’s College of Design, wryly noted this lack of consensus: “Most designers working in the medium of daylight are a bit cloudy when it comes to explaining just what is meant by describing a building or a space as daylit. Or is the correct term ‘daylighted?’ ”
The regulation bodies are not particularly helpful. Updates to the various technical documents to reflect advancements in solid-state lighting or empirical findings between daylighting and occupant health have not occurred with great frequency. It was not until 2013 that the Illuminating Engineering Society (IES) published Lighting Measurement (LM) 83-12, Approved Method: IES Spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE), the first IES-adopted, evidence-based annual daylighting performance metric in the lighting industry.
Then there is the ongoing issue of limited funding for lighting research. In the United States, the Department of Energy and its network of national laboratories have served as key partners for a wide variety of research and development initiatives in areas such as fenestration, glazing, and building systems. Cutbacks and reductions in funding—and even threats to do so—not only jeopardize the future of this work, but also the ability of scientists, researchers, and academics working in these areas to continue these public–private sector partnerships, which provide a direct route to the marketplace for new products and materials.
And, like many industries, daylighting is facing a generational shift in workforce. Many of the practitioners and researchers who developed the canon of studies from the 1980s through the early 2000s have recently retired or will do so in the next few years. While a new generation of lighting designers is stepping into these positions, the ranks are nevertheless smaller, and a cohort of knowledge and experience is further removed from projects of today and tomorrow.
Finally, the new technical capabilities that LEDs offer in lighting controls and the modulation of natural and electric light raise potential ethical questions. Essential to any daylighting strategy has been the connection to view. “I always believe in designing daylight first,” says Florence Lam, a London-based Arup fellow and the company’s global lighting design leader. “It is the direct process of any lighting design. Daylight should come first as the base layer to get [light] right, to get the right view and sequential experience. Then, after that, it’s about applying the electric light overlay.”
But when new control platforms, through LEDs, offer the ability to not only complement variations in daylight, but also to mimic them devoid of real-time settings, the question arises: When the simulation of daylight crosses a perceptual boundary, what in our understanding and experience of light and space are we at risk of losing?