John Bendt 2017-09-14 12:48:20
The impact of window systems on a healthy building Can a building’s windows promote smarter, healthier and happier workers? According to recent studies, good window and ventilation design may improve cognitive function, overall health and sleep function in employees.1,2 Facility managers and building owners are now recognizing the need for improved ventilation to help increase workplace health. CREATING A HEALTHY WORK ENVIRONMENT According to researchers from Harvard’s Center for Health and the Global Environment, individuals spend about 90 percent of their time indoors.3 Where they spend that time can have a significant positive or negative impact on their health. The Harvard study was designed to simulate indoor environmental quality conditions in “green” and conventional buildings and how they affect cognitive function.1 On various days, participants were exposed to conventional office spaces with high concentrations of volatile organic compounds (VOCs) and green office conditions with low concentrations of VOCs. Ventilation also was controlled using green and conventional standards. Participants completed daily cognitive function tests to assess how they would handle real-life situations. The results? On average, cognitive scores were: • 61 percent higher in green building conditions • 101 percent higher in enhanced green building conditions, with higher ventilation rates Another study, headed by a researcher at the University of Illinois at Urbana-Champaign, focused on the impact of daylight exposure on office workers.2 Participants were studied at workstations with exposure to daylight, as well as windowless areas without exposure to daylight. Each participant completed a health-related questionnaire and a sleep quality index to evaluate the subjective quality of their sleep. Office workers with more light exposure at the office reported longer sleep duration, better sleep quality, more physical activity and better quality of life compared to office workers with less light exposure in the workplace. WHY WINDOWS MATTER In an increasingly competitive business environment, many companies are looking to create a healthier work atmosphere to attract and retain talented employees and improve worker performance and productivity. In response, architects, interior designers and contractors are designing and building more attractive and natural work environments. According to Dodge Data and Analytics, the top features of buildings to be used in the next five years include products to:4 • Enhance air quality • Enhance thermal comfort • Provide better lighting/daylight experience • Incorporate biophilic design principles • Enhance tenants’ moods Much of these features will be dependent on a building’s window systems. Employees and workers aren’t the only ones to benefit from these initiatives. Developers, property owners and business leaders can leverage third-party certifications, such as the U.S. Green Building Council’s LEED® v4 and the International WELL Building Institute’s WELL Building Standard™ v1.0, to help them create a vision for improving the health and well-being of their built environment and enhance marketing efforts. Public awareness and greater tenant satisfaction potentially may lead to: • Better tenant retention rates • Lower vacancy rates • Provide ability to charge premium rents • Increase the building’s market value Of course, other factors will have an impact on a building’s vacancy rates and profitability, but significant progress is being made investigating the business case for designing healthier buildings. HOW WINDOW DESIGN CAN ENHANCE BUILDING HEALTH Older window systems that have reached the end of their useful life can contribute to unhealthy air quality. Degradation of sealants, gaskets and the water management system can lead to water infiltration and the potential for mold in the wall cavities. When repair is not practical, replacement windows can prevent further problems — and potentially higher costs — down the road. New window systems can be designed to: • Enhance air quality. Strategies using natural ventilation include wind-driven cross-ventilation and stack ventilation that uses the difference in air densities to provide air movement across a space. In warmer climates, many buildings’ management systems feature automated windows that can be opened overnight to let cooler air in. When practical and safe, windows that can be opened and closed manually can enhance occupants’ sense of well-being and feeling of control over their environment. • Enhance thermal comfort. Indoor temperature plays an important role in task performance in an office environment. A Lawrence Berkeley National Laboratory study found that variations in temperature can produce a decline of 8.9 percent in worker performance.5 About 50 percent of commercial buildings in the United States do not have insulated low-e glass.6 Adjusting the heating and air conditioning turns into a full-time job for building engineers who must try to manage the comfort of those nearest the windows — where outside temperatures and sunlight have a substantial impact —and occupants in different parts of the building. Some building occupants bring in fans or space heaters to compensate for their cold or warm environment, a potential safety hazard. Installing high-performance window systems can enhance the thermal comfort of building occupants. Advancements in high-performance glass have greatly improved their insulating value and solar heat gain (SHGC) properties. High-performance glass manufacturers now can “stack” multi-layer coatings on the glass that total only one-ten-thousandth the thickness of a human hair to improve SHGC and insulating value (U-Factor). Window framing manufacturers have improved thermal breaks, which separate the aluminum on the outside of the building from the aluminum on the inside. This has led to a 75 percent improvement in SHGC and a 600 percent improvement in U-Factor compared to a building with ¼-inch bronze glass in an aluminum frame without thermal breaks. • Provide better lighting/daylight experience: Prior to the invention of low-e coatings, tinted or reflective glass was often used to keep unwanted solar energy from entering the building. The challenge with these solutions is that they often reduced the amount of daylight entering the building as well. Many of the reflective coatings would limit visible light transmittance (VLT) to 20 percent or lower. Today’s high-performance glass has the capability of blocking unwanted solar heat gain while allowing more visible light to come through. Many different combinations of glass substrates and advances in high-performance metal coatings have allowed manufacturers to make products with good solar heat gain mitigation, two to three times as much VLT, and protection from glare. Window and curtainwall manufacturers also have developed other products to leverage the use of natural daylight. For example, architectural light shelves have been proven to reduce the need for artificial lighting in buildings, since they can reflect light deeper into a space. • Incorporate biophilic design principles: Biophilic design is an approach to architecture that seeks to connect building occupants more closely to nature. Window systems are an obvious connection for building occupants to the outdoors, bringing in natural light as well as providing a view. Enhance tenants’ moods: Continuous noise can cause stress-related illness and interrupt activities requiring concentration and disrupt sleep. Cities like New York have passed noise guidelines and regulations that window systems designs must meet. Using different glass thickness, laminated glass and air spaces can improve sound attenuation. Window system manufacturers have a wide variety of products to help buildings manage sound transfer. They use two performance measures and test their products in a certified lab to provide information on how their product performs: – Sound transmission class (STC), an integer rating of how well a building partition attenuates airborne sound. – Outside inside transmission class (OITC), used to determine performance of products in relation to exterior noise, which is often heavy in low frequencies. Working with the manufacturer, an acoustical engineer can assist in determining the correct specification for a building’s window systems. SEEING THE WAY CLEAR When it’s time to consider window, curtainwall or storefront replacement, a manufacturer can help with the planning process. Many companies will provide a complimentary survey, design assistance, energy modeling and budgeting to get the process going. The manufacturer’s engineering experience and network of installers can provide important expertise when evaluating this type of renovation. A building survey from a qualified expert should detail the condition of the components of the structure’s window, curtainwall or storefront systems. Items to be investigated include the glass, framing, panels, gaskets, sealants, hardware, anchors and water management of the system. Based on this survey, a manufacturer can present ranges of options for owners and managers, taking into account lifecycle information, structural concerns, budgetary restraints and implementation strategies. Energy modeling is a reliable way to analyze an investment in new window systems. A variety of tools can be used to examine the impact of improved SHGC, U-factors, reduced air infiltration and condensation. These modeling tools should illustrate the reduction of annual energy consumption, peak energy demand, carbon emissions, daylight luminance, glare, condensation and reduction in HVAC and lighting capacity. After maximizing the new window design for performance and budget, a manufacturer can help with window details for architectural drawings and specifications. Window manufacturers have a network of local installers they can refer to you for bidding the project. They also are helpful in investigating the potential for tax credits, tax deductions and utility rebates. Previous window replacement projects have received federal and state historical tax credits, tangible property deductions, 179D tax deductions (which expired as of the end of 2016, but extension legislation has been proposed7), utility rebates and grants. Working with an experienced building envelope retrofit team that includes the window manufacturer, building owners and facility managers can improve a property’s appearance to attract and retain tenants, expand useable floor space for greater lease value, save on energy and operating costs, reduce maintenance costs, enhance occupants’ comfort and productivity, and ultimately, increase the building’s value. A new window system is a smart way to promote the health of a building and its occupants. REFERENCES 1) Associations of Cognitive Function Scores with Carbon Dioxide, Ventilation, and Volatile Organic Compound Exposures in Office Workers: A Controlled Exposure Study of Green and Conventional Office Environments, Joseph G. Allen et al, Environmental Health Perspectives, Vol. 124, No. 6, June 2016. https://ehp.niehs.nih.gov/15-10037/ 2) Impact of Windows and Daylight Exposure on Overall Health and Sleep Quality of Office Workers: A Case-Control Pilot Study, Mohamed Boubekri et al, Journal of Clinical Sleep Medicine, Vol. 10, No. 6, 2014. http://www.aasmnet.org/jcsm/ViewAbstract.aspx?pid=29503 3) Green Office Environments Linked with Higher Cognitive Function Scores, Harvard T.H. Chan School of Public Health, Press Release, Oct. 26, 2015. https://www.hsph.harvard.edu/news/press-releases/green-office-environments-linked-with-higher-cognitive-function-scores/ 4) The Drive toward Healthier Building 2016, Dodge Data & Analytics SmartMarket Report. http://www.engineering.com/Portals/0/Stories/14871/Drive_Toward_Healthier_Buildings_2016.pdf 5) Effect of Temperature on Task Performance in Office Environment, Ernest Orlando Lawrence Berkeley National Laboratory, Seppänen et al, July 2006. https://indoor.lbl.gov/sites/all/files/lbnl-60946.pdf 6) Windows and Building Envelope Research and Development: Roadmap for Emerging Technologies, U.S. Department of Energy, February 2014. https://energy.gov/sites/prod/files/2014/02/f8/BTO_windows_and_envelope_report_3.pdf 7) Capital Review Group, Jan. 20, 2017. http://www.capitalreviewgroup.com/whats-next-for-the-expired-%C2%A7179d-deduction-3-bills-under-consideration-by-congress/ JOHN BENDT serves as vice president of Apogee Enterprises, Inc.’s Building Retrofit Strategy Team. He assists facility managers in evaluating the benefits of energy-efficient building envelope renovations and upgrades by offering free energy modeling, product selection and design assistance, and a network of installers covering North America. Previously, Bendt served as vice president of sales and marketing for Wausau Window and Wall Systems, and as vice president of service and special projects for Harmon, Inc. With more than 25 years in the commercial building industry, Bendt has led many teams responsible for upgrading building systems to enhance the value of commercial buildings.
Published by International Facility Management Association . View All Articles.