Daylighting can reduce energy bills, improve satisfaction
October 18, 2012 - Contact FacilitiesNet Editorial Staff »
Today's tip is to learn more about daylighting as a possible lighting strategy - but a well-thought-out daylighting plan requires more than just windows and skylights.
Along with minimizing artificial light and reducing electricity costs, daylighting can lower HVAC costs. Electric lights produce a lot of heat, but if properly controlled, natural lighting generates hardly any heat at all.
For most buildings, daylighting energy savings range from 15 to 40 percent. It can also improve the productivity and satisfaction of employees, students and even clients and retail customers, since people have a natural attraction and need for daylight. Even retail stores like Wal-Mart have seen the 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.
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 it.
One important point is controlling glare. Direct sunlight penetration in classrooms and office spaces often produces an unpleasant glare on work surfaces, making it difficult to view a computer screen. Properly oriented windows and skylights can admit direct and diffused daylight, producing light while also reducing glare. The selection and placement of windows and skylights should be based upon climate and the design of the building.
Daylighting also must control the amount of heat that enters a building. Window treatments, window films and glazing can shade a window or diffuse direct sunlight. This can reduce overall cooling loads, eliminating the need for a larger cooling system, resulting in additional overall savings.
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, 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.