Light the Way

Human-centric Lighting Puts Occupant Comfort First

HEADER PHOTO: © Warren Jagger Photography

To get the best out of any building application, it is vital to have interior lighting that is well-suited to that space and the occupants who inhabit it. People are happier and perform better when the lighting is attuned to their tasks and lifestyles.

But far too often, lighting can end up being something of an afterthought. When lighting is done well, few people notice it because it’s doing its job. But when something is not quite right, everyone knows it or feels it on some level.

In traditional lighting design, the focus can often be on achieving maximum energy efficiency or placing the lights in a logical progression in the ceiling so that all parts of the space are evenly lit. Fixtures often are picked purely for form factor or aesthetics. Although that approach does the job—in that it delivers illumination for mobility or tasks—it tends to default toward what works best for the building design rather than what’s best for the people who occupy the space.

Instead, more designers are starting to think of lighting from the standpoint of the occupant. What if spaces were designed in a way that emphasizes human happiness and productivity? What if we could use technology to add natural elements to our built spaces? The concept of human-centric lighting seeks to approach lighting in a more holistic way that keeps the end users in mind.

Shift in Focus
For many years, there has been research demonstrating that the human body can be positively and negatively affected by certain types of lights at certain times. The body’s natural clock is governed by circadian rhythms with light providing the greatest impact on its timing and regularity. Still, the idea of creating lighting designs with those types of factors in mind is relatively new.

“Arguably a lot of what we’ve been doing in buildings is value engineering lights,” says Mariana Figueiro, director of the Lighting Research Center at Rensselaer Polytechnic Institute, Troy, N.Y. Figueiro studies how light affects sleep patterns and circadian rhythms. “Architectural lighting isn’t just for vision anymore. Over the past 22 years, our research has shown that lighting—if it is properly designed to deliver the correct amount of light at the right time—can have a major positive impact on wellbeing.”

“We inherently build buildings that are not supportive for us from a human standpoint,” adds Edward Clark, director of CIRCA DIES, an architectural consulting firm out of Washington’s Olympic Peninsula. The firm is focused on creating nurturing designs. “They’re warm and dry and can facilitate a task, but they are not helping us be our best selves in any way, shape or form. Through scientific study and improved technology, we have discovered there are things we can do in buildings to make things better. They’re not super expensive and don’t require a lot of time and effort. They just require a more rigorous, thoughtful process at the design stage.”

Synched Up
All interior lighting is centered toward humans. Humans are the only species on earth who use electric illumination, so all lighting, ultimately, is human-centric. However, what the human-centric trend refers to, more specifically, is a recognition of that fact and design that puts occupant wellbeing first.

In more traditional lighting design, the understanding of human needs for illumination may not have gone much further than making sure there is enough light for occupants to find their way and see what they’re doing. But current understanding of how the body responds to light makes it clear that there’s much more to it than that. As lighting technology has continued to evolve, it has become more possible to respond to the human condition needs in interior lighting designs.

“Today we have so many options with lighting and control technology that we can ask questions we weren’t able to ask before,” Clark says.

“We’ve done some work with the General Services Administration, doing measurements in buildings, and have discovered that most workers are in environments that are too dim during the day. We’ve been so focused on energy efficiency that we’ve really been dropping light levels,” Figueiro says. “You must also account for glare, aesthetics and pleasantness of the space. We need to stop designing lighting just to save energy or occupy a ceiling grid. We need to start focusing on the occupants of the building.”

Individual Control
Part of the challenge of human-centric lighting is everyone is different and has varied preferences and needs related to lighting. There is a lot of discussion about enabling occupants to have some control of the lighting in their space, but there can be difficulties with that approach.

“If you ask a group how bright they want it in the room, everyone is going to have a different answer. If you ask what color temperature is best, everyone will have a different answer,” Clark says. “If you allow occupants the ability to do whatever they want with lighting, it could be a detriment to their peers. But if they are localized and have their own space, they can do whatever they want. The goal is to give people enough control so they don’t feel held hostage but not so much where they are impacting their neighbor.”

“We’ve done research looking at individualized control and what our findings showed is that if you give people more individual control of their lights, they are happier. We don’t show that they perform better but they like having control of their lights,” Figueiro says. “People are individual and so are spaces. If you have an office where everyone arrives at 8:30 a.m. and leaves at 5 p.m. every day, you can probably have a general lighting framework that is controlled by a master control system delivering the light they need during the day. But if you have an office where people arrive and leave at different times or a hospital where you have to account for patient sleep and night-shift needs, a single system isn’t going to do the job.”

Although there are ways to design overall lighting systems with an eye toward occupant comfort, many believe the trend will ultimately point toward more individualized lighting and control systems.

“People are very different in how they respond to light—even the fact that you have people of different ages in a building. Older people are going to need different light than younger people to see the same thing,” Figueiro says. “Designers and manufacturers often tend to think of lighting as part of the building, and I think what we need to do is start looking at lighting as individual and part of a person’s work environment, the way that a computer is part of a personal workspace.”

Path to Adoption
Clark points out, in many ways, human-centric lighting has a parallel to the early green building movement. At the beginning, sustainability competed against other considerations in the minds of owners and designers and often the reaction was to focus on costs first. But over time, owners began to see the long-term benefits and client demand grew.

“Human-centric lighting is automatically perceived as more expensive because it is a new paradigm,” Clark says. “There might be some cost associated with the increased gadgetry and controls, but I’m a firm believer that the increase in cost is rewarded by increased occupant performance. Human resource professionals know that people are going to work better, faster, happier and stronger when they are in the right environmental conditions. As clients begin to see and understand this more, the curve of adoption will improve.”

Whether for new construction or a retrofit or remodel, some targeted changes to lighting and interior design can make a very big impact.

Clark says: “Finishes are also very important; the world is a filter for light with every reflection, refraction and transmission altering the spectral content of light. The interaction of light and materials is paramount. It doesn’t take a lot to make a space better. It’s just a little more thought at early stages to develop a strategy that is nurturing.”

Daylight
Although great pains are taken to set the right brightness and correlated color temperature for interior electric light, working natural daylight into a space can be very helpful in the effort to create an environment that is comfortable and productive for human beings. But as great as daylight is, there are many things to consider to properly bring it into a space, including how to manage the optimal amount of daylight without obstructing views of the outdoors.

“I always preference the daylight response first,” explains Edward Clark, director of CIRCA DIES on Washington’s Olympic Peninsula. “It is important to understand the windows—how to shade them and how to keep them open. It’s important to allow protection from glare so you don’t have to pull the blinds down. You get a lot of positive impact from natural lighting that goes beyond the light itself. Being connected to the outside and to social and cultural context are all good for people.”

“Daylight is a great source for everything,” adds Mariana Figueiro, director, Lighting Research Center, Rensselaer Polytechnic Institute, Troy, N.Y. “It’s a great light source for color rendering, for circadian rhythm and for visibility. The only problem is that it isn’t always done well in the built environment. Just because there is a window doesn’t mean everyone is getting daylight. If a person isn’t near the window, they aren’t getting the benefit of the light. And if the sun is hitting an occupant’s face, he or she will just close the shade. If you’re going to do human-centric daylight, you have to think about where you place the furniture and what partition heights are so the light can actually get around the space.”