Local Electrochromic Window-Lighting Systems

Results:
We successfully developed working prototypes of electrochromic (EC) windows integrated building equipment communications system (IBECS) network components. Additionally, we conducted the nation's first full-scale demonstration of EC windows; further tests are planned.

The objective of this U.S. Department of Energy (DOE) synergistic research was to determine the energy-efficiency and qualitative benefits of large-area EC windows in full-scale applications. A full-scale monitored field study was conducted comparing the performance of an EC window combined with a dimmable electric lighting system to a static window with the same lighting system. Daily lighting energy use was six to 24 percent less when compared to a static 11-percent transmittance window and ranged from three percent less to 13 percent more when compared to a 38-percent transmittance window. Window brightness control and interior daylight levels were improved with dynamic window control. A new test facility has been built where additional, more comprehensive measurements of EC windows will be made in summer 2003.

Interior view of test room B on a partly cloudy day. Left: The EC windows are in their clear state at 10:30 under diffuse light conditions. Right: When sun enters the window, the EC window switches to its fully colored state by 10:50 (right).

Downloads and Links:

• "Electrochromic Windows for Commercial Buildings: Monitored Results from a Full-Scale Testbed." Lee, E.S., D.L. DiBartolomeo, and S.E. Selkowitz, Ernest Orlando Lawrence Berkeley National Laboratory (LBNL), Presented at the 2000 American Council for an Energy-Efficient Economy (ACEEE) Summer Study on Energy Efficiency in Buildings, August 2000. (417 KB, 17 pp)
   
• "Application issues for large-area electrochromic windows in commercial buildings." Lee, E.S. and D.L. DiBartolomeo, LBNL, May 2000. (522 KB, 25 pp)
   

Contact: Eleanor Lee, Lawrence Berkeley National Laboratory (LBNL), (510) 486-4997