Thematic Network: Energy in the Built Environment

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JOE3-CT97-0068 EnerBuild RTD part.N21-
SMART WINDOW POLYMER NETWORK LIQUID CRYSTAL
WITH REFLECTIVE, SCATTERING AND CLEAR STATE
Co-ordinator Marc Casamassima ADEME
Sophia-Antipolis 500 route des Lucioles 06560
Valbonne - France Marc.Casamassima_at_ademe.fr Prese
nter Pierre Sioux LPMC-UMR 6622 CNRS-Universit
é de Nice Parc valrose 06108 Nice -
France Sioux_at_unice.fr
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Abstract The present project concerns the
development of smart windows based on glazed
component including polymer network liquid
crystal (PNLC) films. The final objective
consists in a smart window realization with the
integration of monitoring and self - regulation
devices in a glass panel. The solar control
system will be defined according to the
architectural requirements.
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Approach 1 - Active film elaboration
(2x2cm) PNLC Technology (Polymer Network
Liquid Crystals) 2 - Elaboration Glazed
component (A4 to 60x80cm) Switchable glazed
component 3 - Evaluation Smart window
development (A4 to 60x80cm) Architectural
requirements and solar performances Industrial
Equipment required
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• Project specifications
• 1 - ACTIVE FILM ELABORATION (2x2cm)
• Polymer Network Liquid Crystal (PNLC)
• Microcomposite Polymer network mechanical
  properties
• Liquid crystal Electro-optic
  medium
• Three optical states, large size, no surface
  treatment, curved surfaces.
• Three Optical states
• Reflective
• (planar configuration of liquid crystal)
• Scattering
• (Focal conics configuration of liquid crystal)
• Transparent
• (homeotropic configuration of liquid crystal)
• Bistability
• Transition between stable states by electric
  field pulses
• Gray scale (multiple optically different states
  stable in absence of an applied field)

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• Results
• 1 - ACTIVE FILM ELABORATION Selective film
• Objective
• Obtention of the three optical states - Study of
  the electrical control.
• Project status
• The three optical states are obtained
• Control of the reflection wavelength
• Optimisation of electro-optical properties
  (transparency, threshold voltages.)
• Large temperature range (larger than100C)
• Thanks to
• Optimisation of mixture formulations
• Optimisation of polymerisation conditions

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Results 1 - ACTIVE FILM ELABORATION Selective
film Modification of the
reflection wavelength
OFF-state Reflectance
Transmittance
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• Project Specifications
• 1 - ACTIVE FILM ELABORATION Broadband film
• The higher the broadness, the higher the light
  modulation is.
• Objective
• Broadness expected in the proposal 150 nm
• Results
• Several methods have been implemented
• Obtained values typical examples
• Wavelength 550 nm Broadness 200 nm
• Broad reflection to scattering state
  reversible
• Broad reflection to transparent state
• reversibility is to be improved (scattering)
• Wavelength 1mm Broadness 300 nm Broad
  reflection to scattering state reversible
• Broad reflection to transparent state
  reversible
• Wavelength 1.5 mm Broadness 400 nm Broad
  reflection to scattering state reversible
• Broad reflection to transparent state
  reversible

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• 2 - ELABORATION GLAZED COMPONENT
• Objective
• Switchable glazed component
• Improvement of support material
• Deposit of the film
• Electrical connections
• Assembly process
• Control system
• Characterisation
• Project status
• Implementation of a method allowing the
  increase in size sample.
• Implementation of an assembly method
• To be transferred industrial equipment
  required

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Results ELABORATION GLAZED COMPONENT Project
status Increasing the sample size
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JOE3-CT97-0068 EnerBuild RTD part.N21- 10
Results Project status Example of
characterisation Sample HG 18 - Width 250nm-
Mean wavelength 1.1 mm Variation of solar and
luminous transmittance as a function of voltage

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JOE3-CT97-0068 EnerBuild RTD part.N21- 11
ELABORATION GLAZED COMPONENT Project status
Example of characterisation Sample HG 17- Width
70 nm-Mean wavelength 480nm Transmittance and
reflectance as function of voltages and
wavelengths
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EVALUATION / GLAZED COMPONENT Project status
Example of simulation Variation of the luminous
and solar transmittance for a fixed width window
and a translation of the window from 0.3 to 2.5
mm. The wavelength broadness of the window is
chosen successively between 150 and 500 nm,
?l250 nm, lml545 nm 100.0gt gt
0.2 ?l250 nm, lml525 nm 100.0gt
gt 60.7 Important solar
transmittance modulation when the wavelength
broadness of the window increases.
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MARKET REQUIREMENT
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• OUTCOME Duration 42 months - Remaining time
  9months
• Materials
• Film with selective reflection OK
• Film with broadband reflection first
  feasibility -
• to be improved
• Assembling
• The increase in size of the samples has been
  made in laboratory conditions.Now the increase in
  size must be carried out in pre-industrial
  conditions
• Characterisation
• Important modulation of luminous transmittance,
  to a lesser extent in solar transmittance.
• Could be increased by further increase of
  reflection band broadness
• Market requirements
• Possible applications switchable sun
  protection systems (fenestration systems as well
  as switchable interior walls)
• Fondamental great interest in
  implementing
• new methods to further increase the reflection
  band broadness
• Industrial need of pre-industrial
  machine allowing film preparation
• Market Selective case marketing
  approach
• Broadband case functional analysis