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2/17/2009

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Daylighting Advantages And Disadvantages

Compiled by FacilitiesNet Staff

Daylighting is one environmentally responsible strategy garnering corporate interest. The problem is that as a new technology, the advantages and disadvantages of daylighting aren't yet well understood by facility managers.

While most facility managers realize daylighting involves natural light, not all know that a well-thought-out daylighting plan requires more than just windows and skylights on a building. Here are a few daylighting advantages and disadadvantages to consider before implementing a daylighting plan.

Daylighting Advantages

The overall objective of daylighting is to minimize the amount of artificial light and reduce electricity costs, but it can also lower HVAC costs as well. Electrical lighting produces a lot of heat, whereas, if properly controlled, natural lighting generates hardly any heat at all.

For most buildings incorporating daylighting, the overall energy savings range from 15 to 40 percent. Although energy savings and sustainability may be the reasons companies initially opt for daylighting, it can also have an impact on the productivity and satisfaction of employees, students and even clients and retail customers.

People have a natural attraction and need for daylight. Studies suggest that daylighting has a direct impact on well-being, productivity and overall sense of satisfaction. Even retail stores like Wal-Mart have seen the environmental and monetary benefits of daylighting for both employees and consumers. In an experiment, stores that included skylights over certain departments found that overall sales per square foot were higher in the departments lit by natural light.

Daylighting Disadvantages

Although daylighting can provide numerous positive results in regards to worker performance, if a daylighting program has not been executed properly, it can produce negative results. A few strategies can help facility executives overcome the challenges of daylighting.

A high-performance daylighting system may initially require a significant investment. However, if the project team uses an integrated, strategic design approach, a company’s overall long-term savings make up for any initial dollars spent on daylighting.
One important point is controlling glare. Direct sunlight penetration in classrooms and office spaces often produces an unpleasant glare on worksurfaces, making it difficult to work or view a computer screen.

The proper orientation of windows and skylights can admit direct and diffused daylight, producing the best combination of light for a building while also reducing glare. The selection and placement of windows and skylights should be determined by the amount of light needed and be based upon climate and the design of the building.

Daylighting also calls for controlling the amount of heat that enters a building. Because the sun is such a powerful source to light buildings, it can also produce tremendous amounts of heat. If not planned properly, using natural lighting can result in undesirable heat gains.
It may seem that it would be difficult to increase the amount of light without bringing in extra heat. However, the use of window treatments, window films and glazing can shade a window or diffuse direct sunlight, minimizing heat gain. This can reduce overall cooling loads, eliminating the need for a larger cooling system, resulting in additional overall savings.

Too much heat or light are not the only challenges associated with daylighting strategies. Some architectural features, such as a building’s roof, atrium shapes or a building’s angles, can prevent daylight from illuminating a space. To prevent daylight obstruction, wall openings should be strategically placed within the space.

For example, if elements that can block daylight are located high up in the space they should be as far from wall openings as possible. In a plan that features both open and enclosed spaces, open space areas should be close to the wall openings. This maximizes the effect of daylight, reflecting light deeper into the space.

Sources:
Daylighting: Overcoming Glare and Heat Challenges by Mike Molinski

Daylighting Benefits
by Mike Molinski

Related Articles:
How Daylighting Works



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