Ultimate Daylighting
New Research on the Benefits of Daylight
Numerous studies verify the significant relationship between productivity gains, cognitive responses, health benefits, and daylighting. Forward-thinking architects who design a workspace that includes sunlight, window views, privacy, and individual controls, find access to daylight can have measurable, positive results on the building occupants. A recently published survey, “The Benefits of Glass”4 documents numerous qualitative studies on the advantages of access to daylight in office, education, retail, and health-care environments. Research on the effect on employees who work in buildings that meet sustainable design criteria shows a reduction of absenteeism by those with access to daylight. In studies of retail environments, sales are shown to increase in stores with windows. The research on educational facilities confirms that access to daylight and views in schools can contribute to improvements in student test scores.5
One of these studies by Drs. Wang and Boubekri tested single-occupancy office spaces and documented occupants' preference for office areas with daylight patches. In their research, cognitive scores increased as much as 20 percent above average for those with access to views and/or daylight and 24 percent below average for those without.6 Roger Ulrich, Ph.D., a leading proponent of such evidence-based design and author of Biophilic Design, states that as of 2008, there are more than 50 rigorous studies on the topic of daylight and views. Studies on the effect of daylight to occupants, or “biophilia,” often are influenced by the writings of Erich Fromm and E.O. Wilson, who introduced the term. Writers, social psychologists, and environmentalists believe that humans have a subconscious need to relate to nature. The benefits of access to daylight on building occupants include improvements in productivity, learning, and healing.
One of Ulrich's recommendations to architects and designers working in health care is, that based on his studies, “larger windows should be provided to permit more exposure to daylight and restorative nature views in patient rooms and other spaces where depression, pain, and stress are problems.”7
Window to Wall Ratio and ASHRAE Concerns
The relationship of the area of windows to the area of walls in a building envelope can affect both human behavior as well as energy use in a building. Architects average the heat gain/loss from the building envelope to assure that the building meets strict energy standards and the more windows, the harder it is to maintain an energy-efficient envelope.
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) introduced a proposal in June 2013, to decrease the ratio of windows to walls by almost 25 percent, as a revision to ASHRAE 189.1, The Standard for the Design of High-Performance Buildings. Their recommendation that the glass area allowed in the prescriptive path from 40 percent wall-to-window ratio (WWR) to 30 percent WWR for buildings less than 25,000 square feet has been met with resistance by researchers, universities, architects, and glass manufacturers.
The conflicts between the size and efficiency of windows to prevent heat loss and the need to provide access to daylight as a benefit to occupants are real issues that architects balance project by project. New window systems are making it possible to argue that buildings can have larger window openings that maintain energy efficiency while providing access to daylight and views of nature.
Net Zero and Other Opportunities
Putting it all together, architects are using their knowledge of high-performance windows and glass to design very high-performance buildings with large expanses of glass. Jim Pattison Centre of Excellence at Okanagan College, in Kelowna, British Columbia, is a net-zero building with large expanses of glass. CEI Architecture selected low-E glass to offer the maximum daylight penetration into the building and to control solar heat gain. This net-zero project is an example of how architects can use large window openings without sacrificing solar performance.
Manufacturers are also incorporating building integrated photovoltaics (BIPV) into buildings that meet high levels of other sustainable design criteria. Designed by SLCE Architects in New York, the Verdesien is a 26-story residential apartment building located at the northern end of Battery Park City. The Verdesian rooftop contains 20.4 kWp of solar cells that are integrated directly into the glazing system. The energy generated by the BIPV goes into the electrical grid reducing the electric load generated by the building. The photovoltaic cells provide 5 percent of the electric load of the building, helping to reduce the demand from fossil fuels and reducing greenhouse gases.
Designed by SLCE Architects, the panels at the Verdesian rooftop contain building integrated photovoltaic panels. Photo courtesy of EFCO, a Pella Company |
Architects who learn more about the unique opportunities provided by new glass, glazing, and window solutions will have the tools that will allow them to provide even more access to daylight and healthy, sustainable buildings.
Jim Pattison Centre of Excellence at Okanagan College, in Kelowna, British Columbia, is a net-zero building. CEI Architecture selected low-E glass to offer the maximum daylight penetration into the building and to control solar heat gain. Photo courtesy of Ed White Photographics |
ENDNOTES | |
1 | Golisano Institute for Sustainability. July 2013 |
2 | Based on data from research conducted by the Department of Occupational and Environmental Health at the University of Iowa. Improved home health for allergy sufferers.http://www.pellanewengland.com/aboutus/environmental-commitment.aspx |
3 | The Artless Word: Mies van der Rohe building art. Accessed: July 27, 2013. |
4 | Guardian Industries, “The Benefits of Glass: A Literature Review on the Qualitative Benefits of Glass on Building Occupants.” Kathy Velikov and Julie Janiski. The University of Michigan College of Architecture and Urban Planning. |
5 | IBID |
6 | IBID |
7 | IBID |
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