Supporting Performance While Saving Energy

Designing solar shades to cultivate occupant well-being and promote whole building function
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Sponsored by Draper, Inc.
By Amanda Voss, MPP

Harnessing Shades and Motorized Controls to Enhance Occupant Well-Being

Shading systems are traditionally presented, first and foremost, as a method to achieve energy cost savings by using natural light and solar heat gain control to lower utility bills and reduce the size of HVAC and lighting systems. While the impact of shading strategies on energy is demonstrable and more easily measurable, one of their greatest impacts is on occupant welfare, and this becomes a definitive advantage.

In modern commercial buildings, the largest amount of money spent annually on operation is invested in people. Wages and other workforce costs represent the biggest chunk of operating expenses, and it is in this area where shading solutions can have the greatest impact.

According to the Productive section of the WBDG, typical total life-cycle costs of private-sector buildings are $200 per square foot per year for salaries; $20 for amortized bricks/mortar cost; and $2 for energy.5 Based on these numbers, even a very small improvement in worker productivity and welfare will have a huge impact. “Buildings can be a more effective, exciting places to work, learn, and live by encouraging adaptability, improving comfort, supporting sense of community, and providing connections to the natural environment, natural light, and view,” the WBDG states.

The WBDG designates five basic design principles that are part of productive buildings:

  • The design promotes health and well-being.
  • The design accommodates the changing workplace.
  • The design integrates technological tools.
  • The design assures reliable systems and spaces.
  • The design promotes comfortable environments.

If the majority of building expenses is related to occupants, increasing occupant comfort and productivity is vital, not only for the occupant but also for the building in the long term. How then can the design professional measure the success of various shading strategies? How can occupant welfare be measured numerically? A business’s productivity can be evaluated at a high level by dividing revenue (earnings before interest, taxes, depreciation, and amortization, or EBITDA) by the number of employees. In manufacturing, productivity is easily measured by dividing production output (widgets made) by production input (labor hours). In office environments, productivity can be much harder to measure. Researchers in occupant welfare and productivity frequently use metrics like absenteeism, employee satisfaction, and retention/turnover to gauge an effect on productivity.

Indoor environmental quality can be characterized by four main dimensions: thermal, visual, acoustic comfort, and IAQ. Using these factors as a guide, window shades have a verifiable impact on improving productivity and occupant welfare.

Photos courtesy of Draper Inc.

Visual stress is a crucial issue for commercial buildings. Shades create healthy levels of light for occupants while preserving views to the outside.

The Impact of Shades on Occupant Welfare: Preserving Visual Comfort

Paramount to occupant welfare is availability of natural light. The human body needs natural light to create enzymes and proteins for a healthy life.

A 2003 study by the California Energy Commission (CEC) found that daylight levels and ventilation rates had a statistically significant impact in several occupant welfare models tested.6 Indoor environmental conditions demonstrated a measurable relationship to changes in office worker performance.

Having an effective electric lighting system does not replace the human need for natural light. A 1994 study found a statistically significant improvement in job performance in offices with windows. The Center for Building Performance and Diagnostics at Carnegie Mellon University looked at the impact of daylighting on productivity and recorded 40 percent gains. Evidence also suggests that workers make fewer mistakes in environments with plenty of natural light.

Therefore, natural light—and the means of getting it into a building—becomes an essential part of designing a building, not just to save on energy but also for maximum occupant productivity. The full benefits of natural light, however, stretch beyond the light itself. Access to window views of the outside also gives workers a connection to nature, which has also been found to have an impact on mood, satisfaction, and performance. On average, major health complaints are between 20–25 percent lower for persons close to an exterior window versus those that work in the interior core of a building, without access to view and daylight.7 Access to windows and daylight resulted in a 15 percent reduced absenteeism.8 Office workers were found to perform 10–25 percent better on tests of mental function and memory recall when they had the best possible view versus those with no view.

However, the incorporation of more windows into building design can bring negative consequences for occupants too. CEC found that windows are perhaps one of the most complex aspects of the office environment. While they can provide an office with daylight, views, ventilation, and a communication conduit with the outside world, windows also create an avenue for thermal discomfort, glare, noise, and distractions in the workplace.

Glare and direct sun on workers’ eyes or workspaces makes it harder to perform basic work functions and actually lowers productivity.

According to the American Optometric Association, the National Institute for Occupational Safety and Health, the Illumination Engineering Society (IES), the Human Factors Society, General Electric Corp., and other authorities, the average office environment requires only 20–70 foot-candles (fc) of light to perform computer and computer/paper tasks. Yet, in stark contrast, most work sites measure 80–120 fc of light. Vision-related problems are reported by a majority—between 61–80 percent—of those who work on computers for 6 or more hours per day.

Visual stress on occupants is a crucial issue for commercial buildings. The Occupational Safety and Health Administration (OSHA) workplace guidelines recognize the debilitating effects of glare causing eye strain, tension, lower productivity, and loss of visual function on electronic screens. The 2003 CEC study showed that the greater the glare potential from primary view windows, the worse the office worker performance, decreasing productivity by 15–21 percent, all other things being equal.

If bright, glary lighting is present, occupants tend to squint their eyes, causing facial muscles to contract. Over the course of the day, this can lead to tension headaches, eyestrain, and visual fatigue.

Because of their unique characteristics, solar shades play an important role in balancing the benefits of daylight and outdoor views against the negative consequences from glare and visual strain.

The flexible characteristics available with solar shade applications help commercial spaces to resolve occupant discomfort from all types of glare, including direct, high contrast ratio, and reflective glare. When the sun is relatively low in the sky and aligns directly with a window elevation, shade fabric density alleviates the direct disk glare generated by the sun’s angle. High contrast ratio glare occurs when the area behind an occupant’s work surface is much brighter than the actual work surface. Shades resolve this contrast ratio by using darker color tones and avoiding colorways with white yarns. Reflective glare caused by a light or bright light source reflecting directly on a worksurface can be reduced by selecting a dark-colored shade fabric. Performance shade fabrics can reduce glare by 70–100 percent, based on color, openness factor, and building orientation, while preserving view through.

Including automated shading optimizes glare control and maximizes daylighting based on building orientation and exterior conditions. Sensors measure and balance exterior light levels with desk illuminance to precisely control the shades, allowing for mitigation of glare and permitting light adjustments, as necessary, to provide adequate work surface illumination.

Glare control during the day is a pivotal reason for window shade use. However, shades can also play a role when the sun goes down. Light pollution can disrupt ecosystems and have adverse health effects on people, animals, and plants. The best way to drastically reduce light pollution is with opaque fabrics. A LEED credit is available for automated shading systems that reduce a building’s nighttime visible light transmission (VLT) to less than 10 percent. The system must be automated/scheduled to qualify for this credit.

Since every building type, design, and location is different, there is no one-size-fits-all solution. There are many types of systems and fabrics that can be used. Whichever type of solution is required, having a system that can react according to the prevailing conditions is important. Local control can be retained to promote individual comfort; however, this can negate all of the other benefits of automation.

Photo: © Brett Drury, Architectural Photography

Solar shades absorb the energy at the perimeter of the building and, via radiation, allow the heat to rise directly up instead of affecting thermal comfort of people further inside the space and creating additional heat buildup by striking more surfaces. By reflecting solar energy away, rather than transmitting it into the building, shades deflect heat transmittance.

 

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Originally published in Architectural Record
Originally published in July 2020

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