With so many different definitions of the ubiquitous term out there, perhaps a broad philosophy of human-centric lighting is the most effective way to explain this science to clients.
By Craig Casey, Senior Building Science Engineer at Lutron Electronics
Last year, one of my colleagues gave a talk at an industry roundtable seminar.* As part of his presentation, he asked the audience of architects, lighting designers, and other building professionals what “human-centric lighting” meant to them. The answers were diverse. Some people thought it had to do with spaces being automated to anticipate the needs of the occupant; others said it was about electric lighting that could be color-tuned for the most flattering displays. Several surmised it had to do with the changing color temperature of sunlight throughout the day and its tangible effects on people.
Finally, one attendee raised his hand. “Isn’t all lighting ‘human-centric lighting’?” he asked. His response goes to the heart of how human-centric lighting should be considered.
Humans are hard-wired to react to light, whether that light is natural morning daylight streaming through our windows or the bluish hues of overhead fluorescents. We may be more attracted to richly displayed produce and colorful clothing in retail outlets or we may associate romance with restaurants that feature low, warm amber illumination that evokes the flattering look of candlelight.
Thanks to the latest technology, we now have the ability to control the lighting in our spaces, whether it’s flicking a switch ourselves, creating a timeclock schedule, installing sensors to monitor space occupancy, or letting smart-control algorithms learn from all of the above. We use shades to let in daylight or minimize glare; we tap smartphone apps to tweak intensity or – in the case of some luminaires – color temperature.
“Human-centric lighting” is, indeed, a term that suggests a broad set of solutions — ones that best serve the people within a space.
Nowadays, that philosophy is easier – and more important – to implement than ever. Building spaces can be evaluated with what’s known as the “3/30/300 Rule,” a formula popularized by the building management firm JLL that estimates companies annually spend approximately $3/sq. ft. for energy, $30/sq. ft. for rent, and $300/sq. ft. for personnel – making people the most valuable asset in a workplace. While a company may be able to save a few dollars by reducing energy or optimizing space usage, it is logical to assume the greatest benefits come from attracting and retaining top-notch employees. For that reason, creating an environment that is comfortable for employees while enhancing productivity should be high on every company’s list.
Award-winning lighting designer Randy Burkett – head of the eponymous lighting design firm in St. Louis entrusted with such projects as the Gateway Arch, Washington’s PNC Place, and Atlanta’s Lenox Square shopping center – says he thinks of human-centric lighting as “a three-legged stool” that combines visual performance (how well a person is performing a task), well-being, and psychological impact.
“If you think about all those, ultimately we roll them all back together and have to create a common lighting design that fulfills those needs as much as possible,” Burkett said at a Lutron-hosted Human-Centric Lighting Roundtable in 2018. “I think it’s just being sensitive to human needs and desires as part of what we can provide for people, whether it’s in an office space, a hospital, a classroom, or a good night out on the town.”
In order to achieve the best in human-centric lighting, it has to be part of a holistic strategy. For example, the Lutron HXL approach is a multi-pronged solution that combines four elements of lighting design: Quality light, Natural light, Connection to the outdoors, and Adaptive and Personalized Control. Here’s why:1
Quality light delivers high-performance dimming, tunable white, and color-saturated light control. Though it’s the latter two components that have gotten a great deal of attention in recent years – thanks to advances in LED technology – don’t take dimming for granted. Besides its proven energy-saving benefits, the ability to provide smooth, continuous dimming performance means enabling a beautiful lighting experience. Moreover, quality light should be compatible with any fixture, allowing the user to combine the utility and excellence of the right fixture design with cutting-edge illumination technology. All of these attributes contribute to space aesthetics and an overall pleasant experience.
Natural light: A human-centric solution can maximize daylight by using shades to both let light in and mitigate glare, but thanks to tunable LED technology, light sources that mimic daylight are also available, allowing for a seamlessness between interior and exterior light throughout the day.3
Connection to the outdoors: The daylight coming through the window is only part of a human-centric solution. Research indicates that a view to the outside – which is among the most popular workplace amenities – promotes well-being and helps satisfy our desire for biophilia [a hypothetical human tendency to interact or be closely associated with other forms of life in nature]. As internationally renowned researcher, author, and professor at Carnegie Mellon University Vivian Loftness noted at the Human-Centric Lighting Roundtable: “Humans have a huge inherent need for connection to nature, and nature includes the circadian qualities of light and the variation and frequency and levels.”4
Adaptive and personalized control: Intelligent systems know when and how to adjust lighting and shading based on occupancy levels, the amount of daylight coming into a space, and even the time of day. Personal control empowers occupants to tailor their experience. Together, smart protocols – which can direct and learn from the data of a variety of lighting and building control products, including sensors, timeclocks, and thermostats – and personal devices, such as remotes or smartphone apps, can leverage technology to create dynamic spaces and deliver the right environment.
Though these elements can be implemented separately, using them together has a multiplying effect. For example, the use of sensors and timeclocks can save energy and even create welcome scenes for occupants, but add in views of the outside and daylight exposure – which are highly desired amenities – and those occupants will likely find the space more attractive. Human-centric lighting design is a holistic pursuit: the ultimate result, measured in tangibles (energy usage) and intangibles (psychological and emotional reaction) is greater than the sum of the parts.