100% GLARE
GPG FINDINGS
023
MAY 2015
ELECTROCHROMIC WINDOWS FOR LAND PORTS OF ENTRY
OPPORTUNITY What is the potential benefit to Land Ports of Entry?
PROVIDE DIRECT LINE OF SIGHT AN UNINTERRUPTED VISUAL PATH BETWEEN THE OBSERVER AND THE AREA UNDER SURVEILLANCE
TECHNOLOGY How do electrochromic (EC) windows work?
TRANSITION FROM CLEAR TO DARK USING PHOTOSENSOR READINGS AND SUN PATH CALCULATIONS M&V Where did Measurement and Verification occur?
LAWRENCE BERKELEY NATIONAL LABORATORY measured glare reduction and occupant satisfaction with electrochromic windows provided by SageGlass at the Donna Land Port of Entry along the Texas border with Mexico.
RESULTS How did electrochromic windows perform in M&V?
100%
GLARE
NIGHTTIME
REDUCTION
VISIBILITY REDUCED
BELOW PERCEPTIBLE GLARE THRESHOLD2
WITH INCREASED INTERIOR REFLECTION3
USER PREFERENCE OVER CONVENTIONAL WINDOWS4
Daylight Glare Probability (DGP) in Vehicle Inspection Booths Facing West Booth with EC windows has much lower glare throughout a sunny afternoon 0.7 0.6 Original glass
Qualitative DGP Interpretation
Measured DGP
0.5
0.4 0.3
DGP is a metric for visual comfort, with values from 0 to 1, representing the probability that a person would experience disturbing glare in a particular situation.
EC
0.2 0.1 0.0
> 0.45..................Intolerable glare 0.40 to 0.45......Disturbing glare 0.35 to 0.40.....Perceptible glare < 0.35..................Imperceptible glare
2:00 2:30 3:00 3:30 4:00 4:30 5:00 5:30 6:00 6:30
Time of day (CST)
DEPLOYMENT Where does M&V recommend deploying electrochromic windows?
LAND PORTS OF ENTRY And other facilities where window glare compromises mission-critical outdoor visibility*
Electrochromic Window Demonstration at the Donna Land Port of Entry. Eleanor S. Lee (LBNL), May 2015, p.4 3 Ibid, p.4 *Subject to evaluation and approval by GSA-IT and Security
1
2
Ibid, p.43
The GPG program enables GSA to make sound investment decisions in next generation building technologies based on their real world performance. www.gsa.gov/gpg
023
MAY 2015
ELECTROCHROMIC WINDOWS FOR LAND PORTS OF ENTRY
OPPORTUNITY What is the potential benefit to Land Ports of Entry?
PROVIDE DIRECT LINE OF SIGHT AN UNINTERRUPTED VISUAL PATH BETWEEN THE OBSERVER AND THE AREA UNDER SURVEILLANCE
TECHNOLOGY How do electrochromic (EC) windows work?
TRANSITION FROM CLEAR TO DARK USING PHOTOSENSOR READINGS AND SUN PATH CALCULATIONS M&V Where did Measurement and Verification occur?
LAWRENCE BERKELEY NATIONAL LABORATORY measured glare reduction and occupant satisfaction with electrochromic windows provided by SageGlass at the Donna Land Port of Entry along the Texas border with Mexico.
RESULTS How did electrochromic windows perform in M&V?
100%
GLARE
NIGHTTIME
REDUCTION
VISIBILITY REDUCED
BELOW PERCEPTIBLE GLARE THRESHOLD2
WITH INCREASED INTERIOR REFLECTION3
USER PREFERENCE OVER CONVENTIONAL WINDOWS4
Daylight Glare Probability (DGP) in Vehicle Inspection Booths Facing West Booth with EC windows has much lower glare throughout a sunny afternoon 0.7 0.6 Original glass
Qualitative DGP Interpretation
Measured DGP
0.5
0.4 0.3
DGP is a metric for visual comfort, with values from 0 to 1, representing the probability that a person would experience disturbing glare in a particular situation.
EC
0.2 0.1 0.0
> 0.45..................Intolerable glare 0.40 to 0.45......Disturbing glare 0.35 to 0.40.....Perceptible glare < 0.35..................Imperceptible glare
2:00 2:30 3:00 3:30 4:00 4:30 5:00 5:30 6:00 6:30
Time of day (CST)
DEPLOYMENT Where does M&V recommend deploying electrochromic windows?
LAND PORTS OF ENTRY And other facilities where window glare compromises mission-critical outdoor visibility*
Electrochromic Window Demonstration at the Donna Land Port of Entry. Eleanor S. Lee (LBNL), May 2015, p.4 3 Ibid, p.4 *Subject to evaluation and approval by GSA-IT and Security
1
2
Ibid, p.43
The GPG program enables GSA to make sound investment decisions in next generation building technologies based on their real world performance. www.gsa.gov/gpg
