Redefining White

By Keith Yancey

I remember my first trip to Paris, The City of Lights. But, because I’m a lighting nerd, I couldn’t help finding the yellow headlights on automobiles particularly striking. Probably because it was so different from the headlights I was used to in the United States at the time. Today, however, I’m seeing more and more headlights in the blue range as opposed to the standard incandescent halogen range of about 2900K. Do we see better under cool light, or is it simply a function of the electric source generating the light? Up until the 1940′s or thereabouts, ‘white light’ for interior architectural applications has had a predominantly warm cast to it, mostly because it was generated by candles or incandescent sources. Since World War II and the widespread use of fluorescent sources, we’ve seen our interiors take on cooler color temperatures. With the advent of LED light sources, it is more efficacious to generate light in the blue range than in the warm range. Are we looking at an even ‘cooler’ future in architectural lighting?

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On a recent project, we were asked to provide very cool (high color temperature) light, in the 6500K range for the general illumination for a teaching environment. The professor was citing studies regarding the impact that quality of lighting has on human health and response, one aspect being color temperature. Specifically, there is research suggesting that our visual acuity is improved by light rich in the blue spectrum vs. the same amount of light that is deficient in this shorter wavelength. Blue light is also more efficacious in low-light situations, enabling better peripheral vision. In addition, there is strong evidence that not only the amount of light, but also the color of light, affects circadian rhythms. A heavy dose of blue-rich light in the morning tends to suppress melatonin levels and helps to wake us up. Of course, on the flipside, exposing individuals to high levels of blue light in the evening has shown disruptions in circadian rhythms and sleep cycles. Folks in the lighting industry are split on the findings-some want the IES (Illuminating Engineering Society) to consider these studies for possible updates for recommended illumination levels, while others think it’s a bunch of hype to sell more ‘full-spectrum’ lighting.

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But do all of these studies and claims provide enough evidence to radically alter our approach to interior lighting design? From a practical standpoint, the fluorescent lamp industry would have to produce new products with higher Kelvin temperatures. Instead of the typical 3000K, 3500K, and 4100K sources, we might see 6000K, 7000K, and even 10,000K. Some people who have worked under such cool lighting say they prefer it. Others say it’s too blue. It certainly shifts the colors of materials, furniture, and people in these environments. In a previous Lam blog piece, Paul Zaferiou refers to the idea that people ‘get used to’ the color of light. His experience, when first exposed to the new task light with an LED source, was a knee-jerk reaction to its color. Over the course of a few months, the source grew more familiar, more natural.

I notice this type of phenomenon as well, whether it’s simply re-lamping a luminaire that has been burned out for a while, or something even more amazing, such as the first time I wore progressive lens eyeglasses – I was convinced I’d never get used to them, yet the eye-brain dialogue has made the wearing of these glasses second nature. I no longer get dizzy when looking down and trying to refocus. My brain has completely compensated for the varying optics in my eyeglasses. “We shape our buildings and afterwards our buildings shape us,” according to Churchill.

Could it be that occupants simply ‘get used to’ their environments? Of course they do! But what type of luminous environment is best? As designers, do we cling to what we’ve done for years? Experience certainly accounts for much of how we design, but perhaps we have to continually challenge our own convictions to not only embrace technology, but also the latest scientific studies. Don’t get me wrong, I don’t believe for a minute that scientific methodology produces good design. I do believe, however, that science itself is based just as much on intuition and reasoning as it is on methodology-therefore, the test results cannot be ignored. We should familiarize ourselves with them, and use our experience and intuition to design environments for humans that not only satisfy biological needs but also uplift the human spirit. And what color white is that? Is it 6500K? My ‘knee-jerk’ reaction is ‘yes and no’.

Consider that we grew up ‘under sunlight’. The color of sunlight changes throughout the day, from day to day, and from season to season. That’s a beautiful thing. And if you look at ‘the studies’, people not only like daylight, but it’s good for our health. For this reason and a host of others, we’re now seeing electric lighting for architectural applications as ‘tunable’. As LED’s become more efficient and more affordable, we’re starting to see them replace fluorescent for ambient interior lighting. And since LED luminaires are capable of changing color in addition to dimming, why not have this ability? Just as we now have ‘daylight dimming’ capabilities with electric lighting to save energy, we will quite possibly have ‘daylight tuning’ capabilities to match the electric light source color temperature to the daylight color temperature, or simply the preference of the user. This could result in even more energy savings, and in better health and satisfaction for the occupants. What’s the color of future white? You decide.

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Photo credits: O Paisson (1), Siddie Nam (2), Lam Partners (3)

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