SSL controls light the way to get WELL (MAGAZINE)
Brent Protzman explains the impact of advanced lighting controls on the Light Concept area of WELL certification, which provides illumination guidelines to minimize disruption to the body’s circadian system, enhance productivity, and provide appropriate visual acuity.
BRENT PROTZMAN explains the impact of advanced lighting controls on the Light Concept area of WELL certification, which provides illumination guidelines to minimize disruption to the body’s circadian system, enhance productivity, and provide appropriate visual acuity.
The goal of the WELL Building Standard, developed by the International WELL Building Institute (IWBI), is refreshing and simple: Promote better buildings to help people thrive. The current standard, WELL v1, focuses on seven concept areas — air, water, nourishment, light, fitness, comfort, and mind. Meeting requirements in each concept helps achieve WELL certification and supports better health and wellbeing in the built environment.
WELL v2 is currently in the pilot phase, and users can register under the new version immediately. According to the International Well Building Institute, once fully adopted, v2 will include “a full suite of enhancements that advance IWBI’s global aim to build a healthier future for all. WELL v2 is informed by key lessons learned from the nearly 1000 projects that are registered or certified in 34 countries across the world”.
The American Public Health Association notes that a poor indoor environment can negatively affect occupants’ wellbeing. Furthermore, studies have shown that employees suffering from poor health are absent more often, lose more work hours, and are less productive than employees without these conditions. The WELL Building standard was developed using an evidence-based approach, and its developers point to research that suggests productivity and health benefits derive from things such as improved ventilation and lighting design.
Tunable white lighting and automated shading solutions are increasingly important aspects of a smart building strategy. Enhanced lighting design is key to creating the right environment for the people in the space. These same strategies can make significant contributions toward helping buildings achieve WELL certification and can make projects easier and less time-consuming by delivering more consistent, predictable lighting performance and simplifying technical complexities.
WELL preconditions and controls converge
Here we will look at the impact of advanced lighting controls on the Light Concept area of WELL certification, which provides illumination guidelines to minimize disruption to the body’s circadian system, enhance productivity, and provide appropriate visual acuity. The Light Concept area includes eleven features, four of which are preconditions that are mandatory for Silver certification, and seven of which are optimizations that can help a building achieve higher levels — gold or platinum — within the WELL standard.
Advanced lighting control solutions can contribute to achieving all four of the mandatory Light Concept preconditions:
- Feature 53: Visual Lighting Design
- Feature 54: Circadian Lighting Design
- Feature 55: Electric Light Glare Control
- Feature 56: Solar Glare Control
Feature 53, Visual Lighting Design, consists of two parts: Visual Acuity and Brightness Management. The goal is to ensure adequate light levels for a variety of activities, improve overall visual appeal, and help provide the necessary amount of light at workspaces without over-illuminating ancillary space. Pairing adjustable direct task lighting with indirect or diffuse ambient lighting allows user customization and good visual acuity while providing more suitable background light (Fig. 1).
FIG. 1. Tunable-white LED luminaires and fixtures carefully placed in key locations provide adequate light levels while minimizing circadian disruption in an office setting that achieved WELL Building certification.
The feature defines required average light levels of 20 fc or more on the horizontal plane, measured at 30 in. above the floor, as well as independently controlled zones of light no larger than 500 ft2. This feature also defines the appropriate brightness and contrast ratios on different surfaces among spaces (e.g., no greater than ±10× in main room than in ancillary rooms) and among surfaces within a space (e.g., surface cannot exhibit 3× greater or lesser luminance than an adjacent surface) to avoid dark spots or excessively bright spots in a room. Digital dimming controls allow the lighting specifier to trim light levels (set maximum lighting output to the appropriate illuminance level) to meet the required contrast ratios.
A lighting design can meet required illuminance with fixtures alone, but this strategy can result in very bright light, which is acceptable earlier in the day but less desirable in the evening when it can negatively affect sleep patterns. Designing an integrated light-and-shade management system with usable daylight enables the shades to help regulate daylight, provide the required illuminance, and mitigate glare, while the lighting controls automatically dim to help save energy.
In addition, the lighting zones must be no larger than 500 ft2, or 20% of an open office floorplan. A digital control strategy can accommodate zoning requirements without the need for complex wiring, and when the furniture or layout inevitably changes, zones can be easily adjusted from a computer with no need to rewire.
The brightness management aspect of Visual Lighting Design maintains luminance balance and requires a design that takes at least two of the following factors into consideration:
- Maximum brightness contrasts between main rooms and ancillary spaces, such as corridors and stairwells
- Maximum brightness contrasts between task surfaces and immediately adjacent surfaces, including adjacent visual display terminal screens
- Brightness contrasts between task surfaces and remote, non-adjacent surfaces in the same room
- The way brightness is distributed across ceilings in a given room that maintains lighting variety but avoids both dark spots, or excessively bright, potentially glaring spots
A digital control solution offers tremendous benefits in pursuit of WELL certification, not only from a client’s perspective but in terms of simplifying design and specification. Starting with robust, flexible, smart technology on the front end simplifies design, installation, setup, and even system adjustments over time. It is important to choose a digital protocol that allows each and every fixture to be individually addressed, delivering results that are more consistent and satisfactory, and making it easier to meet luminance balance considerations as defined previously.
To verify compliance, your project will have to provide a letter of assurance from the architect, a policy document, and spot measurement.
FIG. 2. Advanced SSL controls can achieve WELL Building standard Light Concept objectives by adjusting light output and CCT based on daylight levels and time of day and year, and managing solar-adaptive shading systems in response to varying conditions.
Feature #54 addresses Circadian Lighting Design. This aspect of WELL certification is designed to provide lighting conditions that reinforce natural patterns of the human circadian cycle with appropriate melanopic light intensity in work areas.
The WELL Building standard suggests that interior lighting plays an important role in circadian photoentrainment. Given that people spend 90% of their lives indoors, the WELL standard is designed to address optimal light/dark patterns. The IWBI asserts the body requires periods of both brightness and darkness to properly synchronize circadian rhythms, and insufficient illumination or improper lighting design can lead to a drift of the circadian phase, especially if paired with inappropriate light exposure at night. This informs the requirements of Feature #54.
At least one of the following requirements must be met for precondition Feature #54: 200 equivalent melanopic lux (EML) is present at 75% or more of workstations, at 4 ft above the finished floor, for at least 4 hours per day (9 AM to 1 PM) every day of the year; or 150 EML is provided at all workstations.
EML is calculated by measuring the visual lux and multiplying it by a ratio that correlates to the impact the light has on the body’s sleep/wake cycle. Shorter-wavelength light (blue) has a stronger biological response than longer-wavelength light (yellow or red). The ratio of shorter-wavelength light will be higher due to the impact on the body’s circadian system. The ratio for a 6500K-CCT fluorescent light might be 1.02 because it has a lot of stimulating blue light, while the ratio for a 2950K fluorescent light may be 0.43 because its spectral power distribution (SPD) contains lower amounts of stimulating blue light.
It is possible to meet the EML requirements in a number of ways.
Bright and warm CCT fixture. Even though it has a low ratio, if the fixture is bright enough, it will meet the EML requirements. The drawback is that this will use more energy and it may be brighter than necessary. With a dimming system and a timeclock, this can be an acceptable option but is likely to make it more challenging to meet both LEED and WELL requirements as annual energy costs will be higher.
Cool CCT fixture with a higher ratio. This allows you to use less power to meet the EML requirements. The drawback is that employees who work under this light in the evenings may have their circadian rhythms disrupted due to the biologically active light. Even with a dimmer, this light could disrupt occupants’ sleep cycles.
Tunable white fixtures. Tunable white fixtures and controls can be programmed to provide a high CCT and high ratio in the morning. They also allow lighting to be adjusted automatically and unobtrusively over the course of the day in an effort to minimize sleep disruption. For example, short wavelengths of light (the violet/blue end of the visual spectrum) can be included earlier then scaled back in the afternoon and evening. Upfront costs of tunable white fixtures can be a potential roadblock, but the advantages are significant.
Feature #55 outlines a two-part approach to Solar Glare Control. Part 1, luminaire shielding, defines the shielding angles that must be observed for lamps in regularly occupied spaces with varying luminance values. Part 2 is focused on glare minimization in seating areas. Luminaires more than 53˚ above the center of view must have luminance less than 8000 cd/m2. Lighting controls that enable high-end trim help to meet the identified brightness thresholds.
Feature #56 is Solar Glare Control. Feature 56 is intended to avoid glare from the sun. Strategies block or reflect direct sunlight away from the occupants, and key requirements address all view windows (glazing less than 7 ft above the floor) in regularly occupied spaces.
Bright light during the day is conducive to good health, but uneven levels of brightness in the visual field can cause visual fatigue and discomfort. Glare, or excessive brightness, is caused by light scattering within the eye (intraocular scattering), thereby creating a “veil” of luminance that reduces the luminance contrast as received by the retina. In buildings, sources of glare are often unshielded or poorly shielded light, or sunlight directly hitting the eye or reflective surfaces.
To meet Part 1 of Solar Glare Control — View Window Shading — a building design must include one of the following:
- Controllable or automatic interior window shades or blinds
- External shading system set to mitigate glare
- Dynamic glass that can modulate to reduce transmittance by at least 90%
To meet Part 2 — Daylight Management — requires inclusion of least one of these five daylight strategies:
- Interior window shading or blinds that are controllable by the occupants or set to automatically adjust to minimize glare
- External shading systems that are set to mitigate glare
- Interior light shelves to reflect sunlight toward the ceiling
- A film of micromirrors on the window that reflects sunlight toward the ceiling
- Variable opacity glazing, such as electrochromic glass, which can reduce transmissivity by 90% or more
Automated, solar-adaptive window shading systems help to reflect harsh, direct sunlight away from occupants while still preserving highly-desirable view. An integrated lighting-and-shade control system allows lighting controls to maintain illuminance inside the space in response to shade settings that help control glare (Fig. 2).
Building awareness of WELL
The WELL Building Standard is helping to raise awareness of lighting designs that best support the people who live and work in a space. The preconditions highlighted in this article can put projects on track to WELL certification, and lighting control solutions can significantly impact Light Concept optimizations required for WELL Gold and Platinum certifications.
Lighting manufacturers continue to develop intelligent products and solutions that help lighting designers, specifiers, architects, and engineers deliver ever-more comfortable, sustainable, productive work environments.
BRENT PROTZMAN, PhD, is director of building science and standards development at Lutron Electronics and a member of the WELL Light Concept Advisory. He has a PhD in architectural engineering from the University of Nebraska and is the author of numerous published articles on building science. Protzman is a former professor and researcher in the Building Systems Program at the University of Colorado where he focused on human factors in lighting, daylighting performance, and energy audits and simulations. With this expertise, he has unique understanding of the interactions between human-centric design, operational efficiency, and sustainability. Protzman serves on the IES Daylighting and Papers Committees, on the board of directors for the AERC (Attachment Energy Ratings Council), and is often a peer reviewer for journals and grant reviews.