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

The Impact of Shades on Occupant Welfare: Maintaining Thermal Comfort

In addition to glare, thermal comfort contributes directly to job performance and productivity.

Indoor temperature is one of the most fundamental characteristics of the indoor environment. The indoor comfort level can be controlled with differing accuracy, depending on the building and its HVAC system.

Thermal conditions inside buildings can vary considerably over time, for example, as outdoor conditions change, and also spatially within buildings. Recent research conducted by a team from the Helsinki University of Technology and Lawrence Berkeley National Laboratory demonstrates that indoor temperature affects several human responses, including thermal comfort, perceived air quality, sick building syndrome symptoms, and performance in work.9 The results of multiple studies analyzed by the team showed an average relationship of 2 percent decrement in work performance per degree Celsius when the temperature is above 25 degrees Celsius. The Helsinki team reported that, in a large U.S. study, 50 percent of the subjects stated that they preferred a change in their thermal state, 38 percent of subjects in winter were dissatisfied with thermal conditions, and almost 50 percent of the thermal conditions during summer were outside of the thermal comfort zone.

Lawrence Berkley National Laboratory reported that 18.4 percent of complaints were classified as indoor environmental complaints in a dataset that was collected from 575 buildings in the United States. Of those, 77 percent of indoor environmental complaints were about conditions perceived as too hot or too cold.10

With a building’s thermal comfort falling between such a narrow ideal to maximize occupant welfare, preventing excessive heat gain and loss through windows becomes paramount. Energy from the sun is short wave and carries little heat. Heat is only produced when solar energy is absorbed by a surface and is then radiated as long-wave infrared (IR) energy. Once the solar energy has passed through the glass, it is primarily captured inside the building—especially if low-E2 glazing is used. At this point, it becomes an additional load for the HVAC system. To ensure well-being and productivity, the WBDG recommends a holistic design approach, including the use of solar shading products. 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 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. Therefore, window shades are an excellent way to stop sunlight from hitting interior surfaces and creating solar heat gain. They also stop sunlight from being absorbed directly by occupants and decreasing their thermal comfort. How successfully a shade combats heat gain is mostly due to the exterior fabric color. Generally, fabrics with a lighter exterior color reflect more solar energy than darker colors, meaning they are better at keeping out the heat. Notably, however, certain manufacturers have developed fabric technology treatments that allow even darker colors to reflect more of the sun’s rays.

The Impact of Shades on Occupant Welfare: Preserving Acoustic Comfort

Sound as a detriment to well-being is a recently scrutinized factor. Exposure to noise sources such as traffic and transportation have been shown to hinder the health and well-being of people in a number of different ways.

Built environments can harbor sounds that are distracting and disruptive to work or relaxation. Employee surveys show that acoustic problems are a leading source of dissatisfaction within the environmental conditions of an office. As acoustic comfort is determined, in part, by the physical properties and contents of environments, and recognizing that occupant welfare means that the indoor environment should be a place of comfort, WELL aims to shape spaces to mitigate unwanted indoor noise levels and reduce exterior noise intrusion to enhance social interaction, learning, satisfaction, and productivity. In 2019, the global commercial flooring company Interface released the results of “What’s That Sound?” This is a workplace study uncovering how sound and acoustics impact employees in business environments. The survey, conducted in partnership with Radius Global Market Research, reveals that noise negatively impacts a majority (69 percent) of global employees’ concentration levels, productivity, and creativity.

While shading systems are not a major part of an overall strategy to enhance acoustic well-being for occupants, they do have a role to play. Shade fabrics can be tested and rated with a noise reduction coefficient (NRC) value. Knowing an NRC value helps equip design professionals in choosing a fabric that will absorb sound in that range. For example, a shade fabric with an NRC of 0.60 will absorb 60 percent of the sound that hits the fabric, as long as the shade is deployed.

The Impact of Shades on Occupant Welfare: Enhancing Indoor Air Quality

The quality of the indoor environment needs to be a dominant design concern, as people spend approximately 90 percent of their time in enclosed spaces.11

While indoors, inhalation exposure to indoor air pollutants can lead to a variety of poor health and well-being outcomes. Health effects associated with exposure to indoor air pollutants can be short and long term, and can range in severity. Building materials, furnishings, fabrics, cleaning products, personal care products, and air fresheners can all emit volatile organic compounds (VOCs) or semi-volatile organic compounds (SVOCs) into the indoor environment. Outdoor air pollution can also influence indoor exposure.

CEC’s 2003 study found that indoor environmental conditions have a measurable relationship to changes in office worker performance. The combination of physical comfort conditions considered—illumination, view, ventilation, and temperature—typically accounted for 2–5 percent of variations in worker performance.

Achieving the goal of clean indoor air requires both professionals and building users to engage not just in the conversation but also in the implementation of adequate approaches. WELL recommends proper management of IAQ by eliminating individual sources of air pollution as well as through adequate design solutions and human behavior modification. Shades play an important role in IAQ. Not only do they provide view, proper illumination, and temperature modification, but carefully selected shade fabrics also ensure that no harmful off-gassing or VOCs will be emitted in the interior. Manufacturers offer a range of GREENGUARD Gold-certified fabrics to safeguard buildings as environmentally responsible, profitable, and healthy places to live and work.

Photo: © Timothy Hursley

Window shades allowed the LEED Platinum-certified Heifer International headquarters building located in Little Rock, Arkansas, to maintain its designed efficiency while fostering occupant welfare.

Translating Occupant Welfare into Dollars and Sense

Supporting occupant productivity and well-being is a supreme design factor for the professional. Ensuring worker comfort against performance detractors, like glare and temperature fluctuations, protects the health, environment, and sustainability of a building and its users.

Often, to support the argument for effective solar-control solutions, their benefits need to be concretely communicated in terms of dollars. Because workforce costs are typically the biggest portion of a business’s operating expense, productivity is a big value driver for solar-control solutions.

In the average office building, more than 80 percent of the total operating expenses are salaries and personnel related costs.10 A “typical” office space floor plate of 24,300 rentable square feet yields 20,000 usable square feet. At an average of 175 square feet per employee, this translates into space for 114 employees. Using a conservative average salary estimate of $40,000 per employee with a 40 percent burden for payroll taxes and other associated benefits, this equals a total labor cost of $6,384,000 annually (114 x [$40,000 x 1.4] = 6,384,000). Therefore, every 1 percent gain in productivity equals a $63,840 benefit annually.

Using the latest research in welfare and energy benefits from shading solutions, what numerical returns on investment can be proven? For temperature control, WELL says that leading research indicates that employees perform 6 percent poorer when the office is overheated.

According to the CEC, glare can reduce productivity by up to 21 percent annually.

Solar shading solutions not only control natural light, reduce energy costs, and manage solar heat gain, but they also have a real cost/benefit return when they improve employee productivity and comfort. Even if their contribution is a small percentage, it is still a large benefit to the bottom line.

 

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Originally published in Architectural Record
Originally published in July 2020

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