Transcript Environmentally Controlled Dynamic Glazing Christopher D. Anderson, Ph.D. Pleotint, LLC Commercial Dynamic Glazing Landscape • Electronically Controlled • Voltage induces a color change • Environmentally Controlled • Direct.

Environmentally Controlled
Dynamic Glazing
Christopher D. Anderson, Ph.D.
Pleotint, LLC
Commercial Dynamic Glazing
Landscape
• Electronically Controlled
• Voltage induces a color change
• Environmentally Controlled
• Direct solar irradiance increases glass pane temperature
causing a change in light transmission
Environmentally Controlled
Dynamic Glazing
• Two types – based on width of switching range
• Thermotropic – Narrow Switching Range
• Distinct threshold temperature divides high and low light
transmission states
• Specular
• below threshold temperature: large %LT
• above threshold temperature: small %LT
• Scattering
• below threshold temperature: weak light scattering
• above threshold temperature: significant light scattering
Environmentally Controlled
Dynamic Glazing
• Two Classes - distinguished by width of switching
range
• Thermochromic – broad switching range
• Continuous change in transmission with increase and
decrease in temperature
• Specular
• Low Glass Temperature: large %LT
• Increasing Glass Temperature: progressively smaller %LT
Thermochromic ECDG Glazing in Action
No direct sunlight = Clear
Direct sunlight = Tinted
Residential Installations
Residential Installations
Commercial Installations
Commercial Installations
Benefits of Environmentally
Controlled Dynamic Glazing
• No Wiring
• No Control Systems
• No Added Maintenance
• Sun is the only “power” supply
• Installation identical to conventional IGU/Window
• Laminated Glass Benefits
• Balances Daylighting with desire for low SHGC
• Currently available in dimensions in excess of 5’ x 10’
• Pairs with glass from any manufacturer
LBNL Evaluations - Denver
• “A Pilot Demonstration of Electrochromic and
Thermochromic Windows in the Denver Federal Center,
Building 41, Denver, Colorado” Eleanor S. Lee, Principal
Investigator http://gsa.gov/portal/content/187967
• With thermochromic windows
• “…annual HVAC electricity use due to cooling equipment
(e.g., chiller, fans, and pumps) decreased 22%, from 2.48 to
1.93 kWh/ft -yr…”
• “Peak cooling load decreased 47%...which, in turn, could
enable downsizing of HVAC cooling equipment (chiller and
cooling tower) by 21%, from 50.1 tons to 39.8 tons…”
• “Annual boiler gas consumption for heating by the C-TC
window decreased 17%...”
2
LBNL Evaluations - Berkeley
• “An empirical study of a full-scale polymer
thermochromic window and its implications on
material science development objectives” Lee, E. et al.
Published in Solar Energy Materials & Solar Cells 116
(2013) 14-26.
• “Annual energy savings in the...perimeter zones were 20–43%
in the hot/cold climate of Chicago compared to the ASHRAE
90.1-2004 Standard prescriptive window.”
• “The TC window was able to produce energy savings that
were greater than an advanced low-e dual pane window...”
• “Savings were due to reductions in HVAC energy use and did
not include lighting energy use savings due to daylight
dimming.”
Methods for Determining Solar
Optical Properties of Environmentally
Controlled Dynamic Glazing
• Lawrence Berkeley National Laboratory
• Edge Heating System - Jacob C. Jonsson, Howdy Goudey,
Charlie Curcija
Modeling in LBNL Software
• Energy Plus
• “…models thermochromic windows using spectral data
that have been input at regular temperature intervals
over the switching range.”
• Window 7
• “Window 7 incorporates this interpolation capability
within the software, enabling the end user to generate
spectral data for any arbitrary window configuration and
at user-specified temperature intervals” Solar Energy
Materials & Solar Cells 116 (2013) 14-26.
IGDB
• Thermochromics have been available in the IGDB
since version 31
• Data available across operable temperature range
• 5 °C, 15 °C, 25 °C, 45 °C, 65 °C, 85 °C and 95 °C
• Validated algorithms determine spectra and properties
at intermediate temperatures is implemented in
Window 7
• Thermochromic interlayer data with NFRC
Acceptance (Approved Interlayer List) is anticipated
in IGDB 38
Current Dynamic Glazing Label
• Environmentally controlled
dynamic glazings fit the current
form of the NFRC dynamic label
• The “Off” state corresponds to the
maximum VLT condition of an
ECDG
• The “On” state corresponds to the
minimum VLT condition of the
ECDG.
Iowa Energy Center
Iowa State University
US DOE Grant DE-EE0004011
• Year-round “real-world” evaluation
• Two thermochromic double
pane constructions tested
• Clear Glass
• Spectrally-selective Glass
• Six ̴1 week periods
• Approximately every
other month
• Paired rooms oriented E, S & W
• Temperatures monitored on
thermochromic windows
Iowa Energy Center
East Windows
Iowa Energy Center
South Windows
Iowa Energy Center
West Windows
LBNL Installation and Evaluation
Environmentally Controlled Dynamic
Glazing and NFRC Ratings/Labeling
• ECDG endpoints (5 °C = “Off” and 65°C = “On”)
supported by data
• Using 5 °C and 65°C interlayer spectral data allows
for straightforward calculation solar optical and
thermal properties for both “Fully ON” and “Fully
OFF” states with LBNL Optics and Window.
What does ECDG Need Going
Forward?
• Clarity on how to obtain NFRC rating/certificate
• Commercial (CMA)
• State and Local Building code compliance
• CEC Title 24
• Residential
• Clarity on procedure for establishing dynamic ratings for ECDG
Environmentally Controlled
Dynamic Glazing and NFRC
Items for longer term consideration
• Language in NFRC documents should be broadened
to better accommodate ECDG
• ON/OFF and OPEN/CLOSED are not perfect descriptors for
ECDG
• Maximum VLT/SHGC and Minimum VLT/SHGC would cover all DG
• Incorporate means of differentiating between electronically
controlled DG and ECDG on labels
Thermochromic Laminate
Transmission vs. Temperature
How Thermochromic Glazings
Work
Thermochromic
Interlayer
7/16” Spacer with Insulating Gas
Low Emissivity
Coating
SHGC
0.37
0.17
Tsol
0.26
0.08
Tvis
0.60
Clear Outside
Glass*
* Optional Tint
0.13
Tdw ISO
Glass
Glass Laminate Assembly
Glass
0.38
0.07
Environmentally Controlled Dynamic
Glazing and NFRC Ratings/Labeling
• Needed to inform consumers
• Residential and Commercial - code compliance &
possible tax benefits
• Who benefits?
• Customers
• Dynamic Glazing Manufacturers – both electrochromic
and ECDG
• Glass Producers
• Glass Fabricators
• Glaziers