When I first wrote about the importance of considering the wavelength of light in each fixture selection three years ago, the whole idea was new to many clinicians and designers. Since then it has become a hot topic that I fear is being misunderstood.
It all comes down to the fascination with tunability. Many designers want to set up tunable lights that will have a low wavelength of light in the morning, slowly adjust up to a higher wavelength in the middle of the day and then work their way down by evening. The idea is to emulate the way the sun provides light to nature. Certainly, there are some places where this makes sense, especially in a unit where sunlight and views outside are not available or severely restricted. But in general, I find this approach a little too simplistic and quite frankly, expensive.
To accomplish this magic feat of simulating the sun’s path with artificial lights requires a comprehensive lighting control system and specialty lights, both of which add a lot to the cost of the electrical system. You know what works just as well and is required by Facility Guidelines Institute’s guidelines anyway? Windows! Let’s design spaces with ample daylight and views to nature and let the sun do its job. Then let’s design lighting for how people really live.
So, how should we use this circadian research if we aren’t going to tune the lights with the clock? My radical idea is to give patients, clinicians and staff a choice and trust them. As a simple example, we recently designed a group therapy room. This room was going to be used for both therapy sessions (talking about feelings) and didactic sessions (learning life skills). The design inherently had two levels of lighting. One central light to evenly spread light to a circle of chairs and can lights to provide task lighting to the occupants and put high CRI light on the whiteboard. All we did was decide to make the central fixture a 2,700K light and the cans 4,000K lights.
If you aren’t familiar, 2,700K is the wavelength of light we receive in the morning and evening. It has a naturally calming effect on our bodies. 4,000K light is the wavelength of light we receive in mid-day. It has a naturally energizing effect on our bodies, improving focus and intensity. It also provides the clearest color rendition. None of this was explained to the staff. We just gave them the building and let them use it. After it had been in operation for a few months, I met with the clinicians to see how the lighting was working out. It turns out that they had been naturally selecting the 2,700K central light for their therapy sessions and the 4,000K lights for their didactic sessions. They didn’t know why. They just knew that light seemed right for that purpose.
There is no reason that a room shouldn’t be filled with 2,700K light at noon if the use is appropriate to a calmer, gentler environment or with 4,000K light at 4 p.m. if the use is appropriate to energy and focus. This is not going to negatively affect the circadian rhythms of anybody who has access to natural light throughout their day.
So, as you consider lighting for your facility, let’s think a little deeper and spend a little less and get it right.