Understanding the importance of human-centric lighting design

The concept of human-centric lighting combines complex design elements — such as circadian rhythms, mood, visual acuity, visual comfort and improved productivity — into a combined holistic approach

By Melanie Taylor, CLD, IALD, LEED BD+C, WSP USA, New York City; and Lilian Fu, IALD, LC, WSP USA, San Francisco September 20, 2019

Learning objectives

  • Learn about the basics of human-centric lighting. 
  • Understand the challenges of lighting design, including meeting codes, standards and energy-efficiency requirements. 
  • Review case study examples that provide guidance on human-centric lighting design. 

Lighting is a key component of all buildings and in high-performance buildings specificallyit is centered on the occupant experience and utility of architectural spaceBut human-centric lighting design is a relatively new term for the industry. It describes an approach to lighting that puts more emphasis on the importance of designing for the needs and comfort of the people who will use the system. 

The concept of human-centric lighting combines complex design elements — such as circadian rhythms, mood, visual acuity, visual comfort and improved productivity — into a combined holistic approach to lighting design. 

When looking at the needs of nonresidential buildings, lighting designers must consider multiple factors before specifying human-centric lighting systems for those facilities. While there are certainly many best practices a designer will consider that will provide benefits in most situations, there are no cookie-cutter approaches, as what may be ideal for one building — such as a building that offers ample daylighting opportunities — may be insufficient for another. 

In the role as architectural lighting designers, we regularly encounter clients who are struggling to navigate the fast-paced changes in the lighting industry. They are attempting to understand the value of LED light sources, the realities and capabilities of smart buildings and the thresholds required to meet or exceed WELL Building Standardswhich includes metrics of lighting for general wellness and occupant comfortClients rely upon designer’s expertise to help them make informed decisions regarding these new technologies and design trends. 

In addition to the well-being of the building occupants, lighting designers assess the factors that are desired or required by the client, such as energy efficiency, applicable mandatory national and local codes (such as ASHRAE Standard 90.1: Energy Efficiency for Buildings Except Low-Rise Residential Buildings), daylighting and lighting controls and operations. Lighting designers continually are challenged throughout the design process to balance the many elements of human-centric lighting for the benefit of the occupants. 

Whether it brightens a renovated building or achieves a forward-thinking vision for a new structure, human-centric lighting will create a lasting impression on a building’s occupants and their performance. It also can influence talent acquisition and retention rates in highly competitive industries where the quality, amenities and overall experience of office spaces are given due consideration.  

Improving user control 

Today, the lighting industry favors the use of LED light sources across the board. These efficient light sources allow designers to control the intensity of light output with more precision through the use of dimming options and the ability to adjust the overall color temperature of light via color tunable LED boards 

With these options, a lighting system is capable of providing more fine-tuned solutions that can be designed for every usage type and support automatic time-of-day changes to the lighting that further improve the lighting’s efficiency and effectiveness respectively. 

Lighting designers also are paying particularly close attention to how people will use the space throughout a typical day and how lighting can help occupants feel more comfortable by allowing them greater control, flexibility and ease-of-use, while providing those occupants with high-quality lighting, regardless of their adjustments 

In a residential human-centric lighting system, the users are provided with more individual control over the lighting in their spaces. They are able to turn lights on/off, dim and tune lighting as they like and as suits their individual needs in real time, no matter what time of day. By comparison, users in a commercial project typically will not have the same individual control of the lighting, particularly in open public spaces. 

Even in workplace design, most users work in an environment that is shared, so the lighting design must favor the overall needs of all facility occupants over individual desires. But that does not mean that individual preferences are ignored or undervalued. Anything the lighting designer can do to help make shared environments work for most of the users — while creating special private spaces with individual lighting control — supports a human-centric design approach. 

Seeking efficiencies 

It’s important to remember that human-centric lighting in and of itself does not necessarily create more energyefficient buildings. As a result, one of the challenges is to meet the goals for human-centric lighting while still being energy efficient. Lighting teams need to work carefully to meet both goals on projects. 

Before any project begins, WSP USA’s lighting designers work with clients to determine how they want to use their space and what their overall goals are — what do they value and what might be unnecessary. The design team does not propose advanced lighting systems if they are not appropriate for a particular project. We do not want to provide systems that are essentially unnecessary solutions to a nonexistent problem.  

It is important to provide a system that provides high-quality lighting design that will meet the client’s immediate needs. But it is equally important to address any potential future needs, such as anticipated growth and expansion of the company and its facility or the desire to accommodate future technological advances that are perceived as having benefits to the client once readily available.  

When designers determine that a more advanced system will work for a client, we walk them through options and help them make educated decisions based on the many factors that come into play; primarily design, performance, budget and schedule.  

Innovative workplace lighting 

Recently, WSP USA developed the lighting design for one of the most compelling and iconic buildings in Seattle — and arguably the entire U.S. — The Spheres, an innovative workplace-conservatory located at the center of Amazon’s corporate headquarters. 

One of the big challenges was creating a human-centric lighting system that would work in harmony with a mini indoor rainforest ecosystem where the plants would thrive, while still maintaining a comfort level necessary for an active workplace. Lighting proved to be one of the most complex aspects of this high-profile project.  

Detailed planning was essential to strike a balance between light levels that would provide horticultural light levels for equatorial plants, yet still remained low enough to create a comfortable space for the human occupants of the space. The solution was found in the use of a complex system of high-output LED sports lighting light fixtures in combination with daylighting sensors, which provided a robust and automatic horticultural lighting system. 

Collaborating with architect NBBJ, the firm was able to design an architectural illumination strategy that created a dynamic, multiuse area housed within The Spheres. As a result, the lighting system supports a program that provides locations for retail, dining, meeting and communal areas designed to encourage open and spontaneous collaboration. 

The Amazon campus represents a combination of different workplace and social spaces designed for its staff. The lighting design focus was on how the spaces will be used and how the lighting and building systems can support the use automatically during time-of-day changes. Individual controls also were carefully placed to ensure ease of use.  

Another key element of the design was to provide for easy, flexible reconfiguration of workplace types — from open office, to private office, to team rooms — on day two, after the staff had moved into their new workplace. Easily reconfigured elements of the design are an oftenmissed feature of human-centric design, but very critical; humans like to have control of the environment.  

One of the client’s top priorities was flexibility and the need for the lighting concept to adapt when there were changes in space usage. Since completion of The Spheres in 2018, it appears that the lighting system has been successful in achieving both priorities. 

Both the plant and human occupants are thriving in the space and the building has since achieved U.S. Green Building Council LEED Gold. 

Circadian rhythms 

Another factor in the creation of human-centric lighting is consideration for the occupant’s circadian rhythms — that built-in clock regulating the timing of our biological processes and daily behavior, making us alert during the day and sleepy at night. A variety of environmental signals help to regulate it, the most prominent one being the cycle of light and dark that follows the path of the sun.  

A lot has been discussed about how the use of electric lighting in buildings can support the body’s circadian system. The exposure to daylight, the quality and quantity of supplemental electric lighting and task-appropriate illumination levels are understood to help improve energy, mood and productivity. 

While the concept has been around for a long time, research and applicability to the commercial industry is still quite young. We don’t fully understand everything about the way light stimulates our circadian system to truly replicate all the natural processes that follow night and day; nor do we know if it is desirable in all cases. Yet, light fixture manufacturers have powered onward, some more carefully than others. 

One research breakthrough was made in the early 2000swhen it was discovered that certain cells in our eyes, called ipRGCs (intrinsically photosensitive retinal ganglion cells), can stimulate our circadian process in the presence of light. One of these ipRGC’s has a maximum sensitivity at a particular wavelength  490 nanometers to be exact.  

After the research results were announced, a lot of manufacturers jumped on the bandwagon and started advertising lighting for health or circadian lighting, all focused on this discovery. Within the past two years, we’ve discovered that the findings are only the tip of the iceberg. There are actually five of these ipRGCs, but there is notable research on only one of them so far.  

This is all very exciting for the lighting industry and the medical community is also very interested. But we’re still all trying to better understand it. 

Lighting and wellness 

Despite a lack of scientific consensus on the use of circadian lighting, we know that highquality lighting does play a role on human comfort and behaviorWSP USA has worked on a number of projects designed around the WELL Building Standard, which provides guidelines for illumination and glare aimed “to minimize disruption to the body’s circadian system, enhance productivity, support good sleep quality and provide appropriate visual acuity where needed. 

There are certainly things lighting designers can provide that help people feel comfortable and give them a sense of well-beingMany of these techniques are common sense measures that lighting designers have always followed, such as providing layers of lighting with both direct and indirect illumination or using techniques to illuminate vertical surfaces in the environment and lighting for visual interest. 

Today, many of the human-centric concepts are being championed by tech companies, who are showing keen interest in creating work environments that maximize staff performance. These companies exemplify how today’s workplace is changing its focus to individuals and their performance, providing them with options to achieve the optimum working environment. Lighting is a key part of that. 

Lighting is particularly important when it comes to facilities such as health care, where people spend most of their time indoors. For these buildings, it is important to provide maximum daylight, as well as ensure that there is good architectural lighting quality.  

The challenge with designing with circadian rhythms in mind is that the parameters can vary from person to person. The beginning and the end of the day is inherently different for each person. This is one reason why there is an increasing emphasis on user-controlled systems, where building occupants can select the type of lighting to suit their own personal circumstances. 

When it comes to creating good lighting quality in buildings, every scheme must account for the economic and architectural considerations as well as the human factor. There must be a balance. 

Functional office spaces 

WSP USA’s lighting design team worked with the Chicago-based architectural firm VDTA to create a lighting system for Balyasny Asset Management headquarters in San Francisco that was both beautiful and functional while incorporating the company’s branding into the design. 

The client’s offices are located on the 42nd floor with great visual access to daylight and views that naturally support circadian health. However, in an open office working environment with multiple computer screens and large windows, managing brightness and eye fatigue can be challenging.  

To work within these parameters, the design focused on recessed low brightness aperture lighting to maximize the views, vertical illumination on perimeter columns to minimize high contrast against the bright sky and a lightly colored interior palette with continuous wall grazing effects at the core to visually balance the overall space. 

Dimmable user controls were provided in all conference and phone rooms, creating further flexibility for the occupants. Common areas such as the café and gym enjoyed a more playful approach to the lighting. General illumination in the gym used hexagonal light fixtures, which mimicked the hexagonal acoustical panels whereas the cafe included luminous pendants peeking below the wood slat ceiling creating a unique visual pattern 

Lighting features also included a backlit company sign in the brightly lit reception areawhich creates an entrance to the open space that complements the building’s amazing views of the San Francisco Bay and cityscape. In addition, a “line of light” along the main path in the office area guides visitors throughout the building, while artwork on display throughout the building is enhanced by lighting that creates the atmosphere usually found in a fine art gallery. 

The use of creative, efficient lighting design to create warm and inviting spaces has made favorable impressions on the employees.  

Guided by a fun, energetic and creative project team and collaboration with a client that was open to fresh ideas for their lighting scheme, all contributed to the successful outcome. It is very satisfying when a client embraces the end result of a complex, challenging design process. 

A brighter future 

The industry is learning more about the effect lighting has on our circadian rhythms. There is a lot of research being completed and evaluated. In order for our role as lighting designers to be effective, we must be fully informed on the latest research findings and to evaluate on our own how it affects how we design lighting systems.  

But that’s only part of the equation: We must also be careful to not use lighting as a means to change peoples’ physiology when we do not truly understand all of the science. We can help our clients understand the current state of research and help them make informed decisions. 

What is the future for lighting design in nonresidential buildings? One thing that is clear is that there will be more technology used to control lighting in commercial spaces. This will allow lighting systems to automatically respond not only when people are using the space, but also the ways in which they are used. Sensors integrated into light fixtures will collect data, which can then be used to fine-tune the operation of spaces and let owners respond to real data on how spaces are used. This will allow them to make better decisions on the types of spaces they build, the maintenance required and the energy they consume. 

It is an interesting and ever-changing time to be a lighting designer. There continues to be momentous changes in our industry with the advent of more reliable LED light sources, color-tuning capabilities, ultraefficient lighting systems and smart lighting technologies. 

We are confident that each of these new and changing elements of lighting design create demand for lighting design services and expertise, as we continue to see a transition from lighting viewed as a generic necessity to a critical component of effective, efficient and desirable building design. 

Author Bio: Melanie Taylor is vice president and national practice leader for lighting design in the New York City office of WSP USA. Lilian Fu is vice president for lighting design in the San Francisco office of WSP USA.