Daylighting

Daylighting and Sustainability

The recent resurgence of interest in daylighting is driven by the increasing cost of fossil fuels and the recognition of global warming as a tangible threat to environmental ecology and human quality of life. The electricity used to light interior spaces makes up a significant part of the overall energy cost for buildings. In the United States, electricity used to light interior spaces accounts for 20–25 percent of the total electrical energy used nationally. In colder climates and during winter months, the practice of naturally heating spaces via solar heat gain can greatly reduce heating costs. Naturally heated buildings require less energy and help minimize the burning of fossil fuels. The U.S. Green Building Council estimates that buildings that successfully use daylighting can conserve 50–80 percent of their normal energy use.

A comprehensive approach to daylighting includes the use of automated or electronic management systems to balance lighting between natural sunlight and electrical lighting. A 2005 study conducted by the Center for the Built Environment at the University of California, Berkley, concluded that installing control systems to properly manage daylit environments resulted in a 65 percent decrease in electrical lighting use.

Cost

Prospective owners should view such green building technologies using a life cycle analysis approach. This type of approach emphasizes long-term energy cost savings, rather than a singular focus on up-front costs of daylighting techniques. Daylighting improvements, similar to all properly calibrated green building measures, should be viewed as investments, rather than sunk costs. In addition, there are numerous positive externalities to daylit environments that can positively affect the bottom line. Some of these externalities include lower rates of employee absenteeism, a healthier workforce, increased productivity, and higher morale. The effect on worker morale and well-being is especially valuable, as it is typically more costly to continuously hire and train new employees than to make investments in creating a pleasant working environment that would help retain the current workforce.

Psychological Connections

In addition to reduced energy use, daylighting affects human psychology in profound ways. The U.S. Green Building Council's Leadership in Energy and Environmental Design reference manual notes that a visual connection with the outside, natural world can result in greater appreciation and respect for nature by building occupants.

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