Solar Daylighting for Improved Productivity, Comfort and Cost Effectiveness

Myths abound about solar daylighting. It produces glare, it produces excessive heat, and it's just too expensive. Despite these past misconceptions, increasingly building owners are learning about effective natural lighting design and its benefits. "Building owners tend to consider daylight sensors or occupancy sensors as avant garde and experimental technology, but the technology is now generations old, and the first costs are not nearly what they might have seen in a building developed 10 or 20 years ago," Joseph Connell, principal, The Environments Group, Chicago.

The Energy Center of Wisconsin in Madison is a private nonprofit organization that works with local utilities and other groups to promote energy efficiency within the state and conduct energy management research. Similar information clearinghouses offering demonstrations, publications, research, and education programs exist nationwide. To promote daylighting in the commercial sector, the center created the Daylighting Collaborative. This program was designed to address the specific needs and interests of building owners and developers. "We are focusing on commercial office spaces and schools – that's where you get the biggest bang for your buck," saysAbby Vogen, project director, Energy Center of Wisconsin, Madison.

Studies suggest that children perform better and have a lower absenteeism rate in educational facilities with daylighting. According to the U.S. Department of Energy's Energy Information Administration, Washington, D.C., lighting, heating, and cooling account for about 75 percent of total commercial energy use, with schools being the largest energy users. Moreover, daylighting, in combination with energy-efficient lighting, can reduce the lighting power density in office buildings without lowering lighting levels.

Research proves what common sense suggests anyway: that natural light in the workplace increases productivity, reduces absenteeism and improves the speed and accuracy with which people perform everyday tasks. Many government regulations and guides have been written to take account of these findings. In fact the educational, retail and productivity benefits of well-designed daylighting are all based upon the same profound and indisputable physiological facts: natural light stimulates and regulates the release of the mood-enhancing neurotransmitter, serotonin by the body. Ultraviolet light from the sun also promotes Vitamin D production, which helps to build healthy teeth and bones by producing calcium.

According to Connell, industrial facilities, such as factories, warehouses, and other facilities with large flat roofs, can also benefit from the solar daylighting introduced by the addition of skylights. In many facilities, initial cost increases for daylighting implementation can be paid back within 36 to 60 months, and overtime daylit facilities can save building owners on energy costs. To educate building owners about cost-efficient natural lighting, the collaborative has developed a statewide education and design assistance program.

"When you incorporate solar daylighting into a facility, you are cutting down on what it costs to maintain that building, plain and simple," says Vogen. The Energy Center encourages building owners to consider energy efficiency as net operating income. The center conducts energy modeling on buildings and follows up with actual performance monitoring. Adds Connell, "Remember the more light fixtures you add, the more air-conditioning you need to add to cool the space down." Effective daylighting with the right glass specification produces less heat than some forms of artificial lighting, thus reducing cooling requirements as well.

For Herman Miller in Zeeland, MI, The Environments Group with local engineers modernized an existing space into a highly efficient daylit facility. Light permeates the space on all four sides, and glazing reduced the heat gain from the daylight. A light-filled concourse and the absence of private offices on the building's perimeter allow each of the facility's occupants access to natural light. In addition to achieving a U.S. Green Building Council (USGBC) LEED™ Silver rating, the building has been transformed into a beautiful, healthy environment that satisfies employees.

"Lighting is one of the most important indicators of satisfaction with a space," says Connell. "Back in the '70s, people talked about freezing in the dark. Energy efficiency shouldn't be looked at as something that takes away people's creature comforts; rather, it enhances them," says Vogen.

According to several studies, solar daylighting in the work environment relates to increases in productivity and an improved perception of spaces by end-users. For example, the Heschong Mahone Group, Fair Oaks, CA studied the correlation between daylighting and productivity. At a chain of retail stores studied by the research group, sales were as much as 40 percent higher in facilities with skylights. In another study by Heschong Mahone, test scores in three elementary school districts were significantly improved in daylit classrooms.

Associations and organizations, such as USGBC or the American Institute of Architects (AIA), Washington, D.C., have created professional development courses to inform design professionals about the tremendous potential of using solar daylighting and how to design with natural light effectively. Acceptance has been slower among building owners and facilities professionals, due to a lack of information and misconceptions about higher initial costs to incorporate daylighting into commercial facilities.

Because seeing is believing, the center has "living labs" – facilities that have been modernized as daylit buildings. These projects include the State of Wisconsin Administration Building, Milwaukee, and the Hoffman Corp. headquarters in Appleton, WI, where facilities managers can tour and examine effective daylighting. "We use the term 'cool daylighting' to emphasize that daylighting isn't just big windows," says Vogen. "It is the orientation of the building, glazing, energy-efficient light fixtures, mechanical systems, and how all these components are impacted by natural lighting." Living labs and other demonstrations of cool daylighting have been created across the country.

Rising energy costs and a greater awareness of green design has encouraged building owners to adopt new ideas, or in this case, reconsider old ideas made new again.