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Best Practice Guide |
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Commercial Office Buildings |
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LightingOffices and WorkstationsLighting represents approximately 22 percent of all electricity consumed in commercial office buildings. Thus, lighting is a major portion of total building operating costs. Retrofits to lighting systems can yield savings as high as 40 percent of current costs, and can easily be fit into routine building maintenance. Retrofits are especially effective in buildings designed pre-1990s, before the widespread use of personal computers. As work moves away from the desktop and onto the computer screen, modern workstations require less ambient light When retrofitting a lighting system, consider two related system components: the ballast and controls. Replacing magnetic ballasts with basic electronic ballasts can save a minimum of 12 percent of energy consumption, more if you invest in premium electronic ballasts. Premium ballasts come in three main types: instant-start, program-start, and dimmable. Controls, which should be matched to the appropriate ballast, greatly improve efficiency and offer higher flexibility to the end user. Occupancy controls shut off lights in empty areas and photosensor controls dim or shut off lights when natural light renders these unnecessary. Either control system can also come equipped with a timer. New technological improvements in fluorescent luminaires have also dramatically reduced energy consumption while improving light quality. Switching out T12 fluorescents for efficient T8s results in higher efficacy (i.e., fewer watts per lumen). T8s last longer, requiring less maintenance over the useful life of the lamp as well as less waste in local landfills. Because light quality is also better, fewer fixtures per square foot are needed, making delamping possible. Fewer watts per fixture and fewer fixtures per square foot result in lower cooling loads, which mean that related cooling costs from operating climate control equipment are also reduced. Despite these dramatic cost savings, many businesses have been slow to turn over outdated T12s. Of the 1.5 billion fluorescent lamps installed in the U.S. commercial sector, 58 percent are still T12s. This is a missed opportunity. Typically, lighting retrofits recoup costs quickly and are excellent, low-risk investments. There are two related system components to consider as part of any lighting retrofit: the ballast and controls. Replacing magnetic ballasts with basic electronic ballasts can save a minimum of 12 percent of energy consumption, more if you invest in premium electronic ballasts. Premium ballasts come in three main types: instant-start, program-start, and dimmable. Controls, which should be matched to the appropriate ballast, greatly improve efficiency and offer higher flexibility to the end user. Occupancy controls shut off lights in empty areas and photosensor controls dim or shut off lights when natural light renders these unnecessary. Either control system can also come equipped with a timer. What is a “light”?
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Business ExamplesSwinerton Incorporated retrofitted the lighting system at its corporate headquarters building. The retrofit successfully reduced energy consumption as well as light pollution infiltrating the surrounding area. Motion sensors were installed to further maximize the benefits of high efficiency fixtures. Glenborough Realty Trust purchases its lighting equipment through Light Source, a specialty lighting distributor and member of the EPA Greenlights program. Light Source maintains an online customized inventory of all lighting equipment in each Glenborough building. This allows Light Source to analyze stock and usage so that they can recommend to Glenborough energy-saving products that last longer or are less expensive, choosing the best products from multiple manufacturers. As the country's largest real estate investment trust (REIT), Equity Office Properties is able to take advantage of economies of scale, including wholesale lighting retrofits. In one effort, Equity Office retrofitted the lighting systems in twenty buildings, reducing costs by $1.7 million. Transwestern Commercial Services retrofitted the lighting system at Irvine Center Towers, replacing magnetic ballasts for high efficiency electronic models, and replacing T12 fixtures with T8s. Motion sensors were used throughout the buildings, and automatic controllers were installed in the outdoor parking garage. Resources Flex Your Power Product Guide: Controls and Sensors and Lamps and Fixtures Consortium for Energy Efficiency, High Performance Commercial Lighting Systems Initiative, November 2004. Northeast Energy Efficiency Partnership, Design Lights Consortium, Knowhow: Office Lighting, 2002. Energy Design Resources, Design Brief: Efficient Lighting Systems, and Design Brief: Lighting Controls, 1998. The Illuminating Engineers Society of America, Discover Lighting! DiLouie, C. Energy Policy Act of 2005 Encourages Energy-Efficient Lighting with Tax Deduction. Lighting Controls Association, Septemeber 2005. |