Since the inception of the Edison bulb, the two central ideas of lighting have been to improve the efficiency of the light source or to increase the quality of the light. Unfortunately for consumers, those ideas have generally opposed each other, resulting in a compromise toward efficiency.
Today, lighting upgrades in commercial buildings continue to focus on reducing energy usage, with a lesser emphasis on light quality.
With lighting accounting for more than one-third of the energy consumed in commercial facilities, and the increased adoption of energy efficiency programs and codes, it’s no surprise that energy efficiency has led in market adoption. However, at what expense?
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Whether new construction or remodel, it has long been the goal of architects and designers to create spaces for human comfort.
The needs of today’s workplaces are changing, from closed to open offices, private conference rooms to collaboration spaces and amenities that simulate home life. Designers are being tasked to create spaces to promote innovation and creativity, delivering thoughtfully designed environments that attract and retain top talent.
The technology explosion and digital age have yielded, now more than ever, more resources enabling designers to create spaces where people prefer to live and work. More specifically, advances in LED technology and constant improvements in efficacy have allowed more flexibility to enhance environments through higher quality light sources.
Evolution of Light Sources
For a space to have a pleasant feel and for colors to appear natural, a light source must render colors in a manner comparable to that of a blackbody radiator, such as the sun. Humans have evolved knowing the sun and then fire as main light sources for millions of years, until the invention of the Edison bulb in the late 1800s.
The incandescent light bulb, consisting of a burning filament, mimics the warmth and high red content of those light sources. For this reason, spaces illuminated with incandescent light sources appear welcoming and generally quite pleasing.
With the invention of fluorescent lamps, incandescent light sources became comparatively inefficient. However, their light quality wasn’t perceived to be as pleasing as their predecessors. In the past few years, highly efficient LEDs have easily surpassed fluorescent lamps in efficacy.
But even with LEDs, the tradeoff between quality and efficacy has remained: to maximize efficacy, typical 80 CRI LEDs are oversaturated in the blue and green spectrums and undersaturated in the red spectrum.
Advances in LED technology have diminished the efficacy gap, creating a market shift toward quality of light initiatives including circadian tuning, tunable white, warm dimming and spectral tuning. The movement toward quality of light is an opportunity for designers to create spaces that humans ultimately prefer.
Supporting More Human-Centric Environments
The latest research conducted by Pacific Northwest National Laboratory (PNNL) and Pennsylvania State University (PSU) supports the idea that the type of light people prefer closely resembles that emitted by a black body radiator, with a greater saturation in red color. This indicates that the current, widely used 80 CRI LED is not ideal for human preference.
To support lighting designers, PNNL also used TM-30 to provide a suggested specification that can be used to target the most preferable light sources: Rf ≥ 75, Rg ≥ 98, 0% Rcs, h1 ≤ 8%. This is a shift from conventional 80 CRI and 90 CRI measurements, but can be used in the same way to define a light source.
Further strengthening the trend toward designing more human-centric spaces, new building standards have also emerged, such as the WELL Building Standard (WELL). Different from LEED, WELL focuses on human health and wellbeing over energy efficiency.
Often described as two sides of a coin, the two programs promote initiatives that enhance the human experience in spaces that are better for the inhabitants and for the planet.
Advances in LED technology, along with new evaluation tools and emerging research in human preference lighting, have enabled a path to specify a color spectrum that humans generally prefer. This preferred spectrum results in more natural skin tones, warmer wood tones and increased vibrancy of objects.
Most importantly, it creates a sense of comfort that humans have learned to appreciate over millions of years. Many studies have confirmed that when humans feel comfortable in an environment, they tend to be more productive, supporting a more human-centric approach to lighting and interior architecture.
Future light sources will need to deliver more than efficiency. They will need to support those who live and work under them, to create comfortable and productive environments.
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