Hanna Andersson Corporation HQ. Photo credit: Nick Merrick / Hedrich Blessing Photographers
In the age of personal health and fitness trackers, many of us keep a close watch on measures like the number of steps we take and the quality of our sleep. But how often do you ask, “Did I get enough light before lunch?” Below, we offer four key takeaways for architects and lighting designers to consider so that the answer is a resounding yes for more office workers.
Based on a new office lighting study co-authored by ZGF, you could be falling short of the daytime light quota prescribed by the WELL building standard. Where you sit in your office and the light sources you look at have a big impact on your body’s circadian function. An increasing awareness around the importance of the right quantity and quality of light at the right times is leading architects and light designers to more closely assess the workplaces they design — and for good reason. Natural light is now widely-considered to be a top office perk and an integral part of our circadian rhythm (see the 2017 Nobel Prize in Physiology or Medicine).
Office lighting design has traditionally evaluated how much electric overhead light falls on your desk to perform tasks like reading and writing — a throwback to the days of pen and pad — but it does not necessarily measure how much light falls on your eyes. The WELL circadian lighting standard is the first to set a daytime target for light intensity and spectra that reaches your eye between 9 a.m. to 1 p.m., a critical window of time to naturally suppress melatonin and boost your mood and productivity. The target is 200 equivalent melanopic lux, a metric of light intensity that is spectrally-weighted to consider the stimulation of the ganglion cells in our eye.
Getting this light in modern offices can be complicated. One of the most significant impacts can be proper orientation of your desk to overhead lighting, which can change over time as desks move. There are other factors such as blinds, which according to one study at the University of Oregon, can be down 50 percent of the year, blocking views and daylight. Another unfortunate reality is that not all of us sit by a window or even face one. There are other light sources to consider such as computer monitors, task lights, or mobile devices like the kind you are likely reading this on.
On top of measuring how much light comes from each of these sources, you need to account for the spectrum of each light, or how much energy in the visible spectrum is present. The more blue and green energy, the more that light source will stimulate your circadian rhythm. At night, Steven W. Lockley, PhD., an expert in circadian rhythms, sleep and jet lag, recommends swapping the blue light for warm light (blue-deficient) as early as possible before bed.
Because no two workspace environments are the same, different strategies are needed to achieve circadian lighting outcomes that meet the WELL. In a newly published research paper, ZGF project architect Marty Brennan and co-author Alex Collins of BBT Architects set out to aid fellow architects and lighting designers with a framework to quantify the total circadian light (all light sources) for each morning hour. After using this workflow to simulate a wide range conditions, design rules of thumb were derived as recommendations to meet circadian light prescriptions. The study was recently published at the 2018 Building Performance Analysis Conference and SimBuild event co-sponsored by ASHRAE and IBPSA-USA.
I. Look toward the light
The more indirect and/or visually comfortable light sources in your view, the better. This includes windows, overhead lighting, computer monitors, task lights and light reflecting off walls. Orienting your desk properly towards your closest overhead light makes a huge difference. In cases where there is little daylight or overhead light, consider a task light, as well as increasing the brightness on your monitor.
II. Tune the light
Incorporating tunable LED lighting which can change the spectrum between 6500K (blue-rich) in the morning and 2700K (blue-deficient) in the evening can effectively mimic daylight and its health effects. Tunable lighting can also save energy in offices with daylight dimming as blue-rich light can meet the WELL with less intensity than a blue-deficient light.
III. Let there be daylight
Daylight is free, full-spectrum and, and ranges from 4000K to over 25,000K (really blue), so it is great at synchronizing your circadian rhythm. There are lots of strategies to let daylight in. Retract window coverings when possible and adjust venetian blinds to preserve view and light. If possible, rotate your desk 90 degrees from the window which reduces contrast while maintaining daylight view. Consider situating workplaces toward the north and west portions of a building which have great indirect morning light.
Dynamic shading devices such as exterior blinds and electrochromic glass are a great investment for owners as they can result in up to 30 percent more hours of glare-free daylight plus views and nearly zero solar heat gain. This bodes well for human satisfaction and productivity.
IV. Bounce the light
Using neutral, reflective materials for interior finishes can be the determining factor between meeting your light quota or not. The impact is biggest with small rooms (personal offices, conference rooms) and diminishes with larger, open offices. However, if you happen to face a wall in an open office, it could be a larger decrease in blue-rich light. Wall washers and surfaces that reflect circadian light will improve light levels.
Light on the Horizon
The new WELL V2 pilot introduces additional pathways to meeting the circadian light feature. In some cases, the equivalent melanopic lux target is lower than 200 and, therefore easier to achieve. As more owners adopt circadian lighting in practice, the more post occupancy evaluations can be conducted to evaluate lighting environments that strive to achieve high health standards. The future of indoor environments is looking brighter.