By Jody Andres, AIA, LEED AP
From the April 2019 Issue
In today’s climate of sustainable design, it’s rare that a newly constructed facility or one being renovated does not include some level of eco-friendly features. Overlooked in the past, daylighting is one of those features and is no longer an afterthought. It could be argued that how to best use natural light should be a primary consideration in the design of any new facility. But why is it so important?
The Physiological Perspective. The bottom line—daylight is good for us. Research has demonstrated the positive effects of exposure to natural light. Daylight has been shown to combat the effects of depression. It can help improve a person’s mood and maintain a calmer disposition. In addition, exposure to daylight is one of the primary ways we can get and maintain healthy vitamin D levels in our bodies.
When we incorporate windows and natural light into facilities, we’re helping fulfill a basic desire for a connection to light and nature. The biophilia hypothesis—introduced by Edward O. Wilson in his book, Biophilia—proposes that humans have a desire to seek out connections with nature and other forms of life. Biophilic design and planning increases access to nature, light, and biodiversity to reduce stress, promote healing, foster creativity, and improve cognitive function.
The Productivity Perspective. In the workplace, daylighting is a critical design element for employers and their facility planners to consider. Not only does daylighting and controlling artificial lights in the workplace save money, but it’s been proven to help create a more comfortable work environment and make employees more productive.
“Daylight and Productivity—A Field Study,” a study conducted by Mariana G. Figuerio, Mark S. Rea, and Anne C. Rea of the Lighting Research Center at the Rensselaer Polytechnic Institute, and Richard G. Stevens from the University of Connecticut Health Center, Department of Community Medicine, explored the occupancy rates, amount of time subjects spent on work-related tasks, and electric lighting operation in daylit and interior offices. They found that people located in windowed offices spent considerably more time (15%) on work-related tasks compared to employees in interior offices. These results matched their hypothesis that people who work in interior spaces would spend less time in their offices and be less productive than people working in windowed spaces.
When it comes to educational facilities, consider the results of the Heschong Mahone Daylighting Study (conducted by Heschong Mahone Group), which involved more than 21,000 students. Study results presented a significant correlation between learning spaces with natural light and student performance, finding that both reading and math scores improved for students in spaces with abundant daylight. Additionally, there was a 20% faster progression in math and a 26% faster progression in reading.
Meanwhile, school administrators are continually seeking the means to retain the best faculty and staff. Abundant daylight in well-designed work environment is sure to be looked at favorably by current and potential employees.
The Economic Perspective. While there are a bevy of health and production-related reasons to incorporate daylighting, we shouldn’t lose sight of the financial benefits. More natural light means a decreased need for artificial light. This trade-off reduces a building’s power consumption. Additionally, latent (passive solar) heat in the winter decreases the demand on heating systems.
Examining Daylighting Strategies
Whether in a school, office, or senior care facility, natural light can benefit building occupants by providing a healthier, more interesting, and dynamic environment in which to learn, work, or live. So, what are some of the best strategies to utilize when incorporating daylighting?
In the case of new construction, orientation of the building is critical. Siting the building on an east-west axis, with south- and north-facing windows is a key design strategy. And with technological advances, windows can be altered to control how much daylight will enter the space. When planning areas that will contain display equipment, such as high-definition televisions and whiteboards, the design team should take special care with window placement to control lighting levels and to prevent glare or blinding conditions in the space.
Daylighting and control options that are becoming standard design elements include sun control and shading devices, light shelves, clerestory windows, tubular daylight devices, and translucent skylight systems. In the case of a renovation, the use of natural light can be further enhanced by using window films to contain glare. While timers and motion sensors designed to reduce light levels are not new, the next wave of sensors actually measures daylight levels in a room (or portion of a room) and adjusts accordingly.
Although at first mention it seems counterintuitive, artificial lighting can contribute to a good daylighting strategy. A popular design element is the installation of direct-indirect lighting fixtures. With these, more than half of the light generated can be directed upward, reflecting off of the ceiling and other surfaces. This results in reduced glare, a more uniform ambient light level with fewer “hot” spots, the need for fewer artificial lights, and decreased energy use and costs.
Modeling And Assessments
Energy modeling and computer generated building models can be extremely helpful evaluation tools when determining daylighting strategies. Using these, facility owners and maintenance staff will not only be able to observe how natural light and views will exist in their building, but they’ll get an understanding of how much energy—namely in lighting and cooling—can be saved. Whether new construction or renovation, modeling should be incorporated to inform the design effort and guide decision-making. As early as possible, the project team should evaluate the most appropriate ways to bring daylight and views into a facility and how these will be integrated with artificial lighting and controls. As more design and product options are entered into modeling software, facility planners are able to make informed design decisions.
Another critical element to consider when pursuing daylighting is assessing lighting quality and levels compared to the visual tasks being performed. Not to be overlooked is controlling glare in environments awash in daylight. Building occupants will close blinds and shades if they decide too much daylight is obstructing their view. This not only removes views to the outside, but may also necessitate use of artificial lights.
When using natural light to help achieve lighting levels, the selection of window glass (based on the orientation of each window) is vital. While spaces that are over lit waste energy and money, occupant productivity may be negatively impacted by inadequate or poor quality lighting. As a guide for determining a good lighting level for most offices or educational spaces, daylight balanced with an average of 40 to 50 foot-candles of artificial light capability is ideal. (A common unit of measurement in the lighting industry, foot-candle is roughly defined as the amount of light that actually falls on a specific surface.)
The benefits of daylighting are numerous and should be enjoyed. When planning your next project, discuss potential strategies with your design team to create an environment where occupants can thrive.
Andres is a senior project architect and the K-12 market leader at Hoffman Planning, Design & Construction, Inc. in Appleton, WI. He is a LEED AP, past President of the American Institute of Architects (AIA) Wisconsin, and the regional representative to the AIA Strategic Council.
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