Daylighting control performance of a thin-film ceramic electrochromic window: Field study results
Control system development and lighting energy monitoring of ceramic thin-film electrochromic (EC) windows were initiated at the new full-scale window systems test-bed facility at the Lawrence Berkeley National Laboratory (LBNL) in Berkeley, CA. The new facility consists of three identically configured side-by-side private offices with large-area windows that face due south. In one room, an array of EC windows with a center-of-glass visible transmittance T_v range of 0.05-0.60 was installed. In the two other rooms, unshaded windows with a T_v = 0.50 or 0.15 were used as reference. The same dimmable fluorescent lighting system was used in all three rooms. This study explains the design and commissioning of an integrated EC window-lighting control system, and then illustrates its performance in the test-bed under clear, partly cloudy, and overcast sky conditions during the equinox period. The performance of an early prototype EC window controller is also analyzed. Lighting energy savings data are presented. Daily lighting energy savings were 44-59% compared to the reference window of T_v = 0.15 and 8-23% compared to the reference window of T_v = 0.50. The integrated window-lighting control system maintained interior illuminance levels to within +/- 10% of the setpoint range of 510-700 lx for 89-99% of the day. Further work is planned to refine the control algorithms and monitor cooling load, visual comfort, and human factor impacts of this emerging technology. (author)
- Research Organization:
- Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
- Sponsoring Organization:
- USDOE. Assistant Secretary for Energy Efficiency and Renewable Energy. Office of the Deputy Assistant Secretary for Technology Development. Office of the Building Technologies Program. State and Community Prog rams. Office of Building Research and Standards; California Energy Commission. Public Interest Energy Research Program
- DOE Contract Number:
- AC02-05CH11231
- OSTI ID:
- 886820
- Report Number(s):
- LBNL--54924; BnR: YN1901000
- Journal Information:
- Energy and Buildings, Journal Name: Energy and Buildings Journal Issue: 1 Vol. 38; ISSN 0378-7788; ISSN ENEBDR
- Country of Publication:
- United States
- Language:
- English
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