Energy Environment & Sustainable DevelopmentThematic Network on Energy in the Built Environment

JOE3-CT97-0068 EnerBuild RTD part.N°21-

SMART WINDOW : POLYMER NETWORK LIQUID CRYSTAL WITH REFLECTIVE, SCATTERING AND CLEAR STATE

Co-ordinator : Marc Casamassima

ADEME Sophia-Antipolis500 route des Lucioles06560 Valbonne - FranceMarc.Casamassima@ademe.fr

Presenter : Pierre Sioux

LPMC-UMR 6622CNRS-Université de NiceParc valrose06108 Nice - FranceSioux@unice.fr

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JOE3-CT97-0068 EnerBuild RTD part.N°21- 1

THE PARTNERSHIP

Overview of the consortium

OrganisationName

Type Size Role Country Organisation's(business) activity

ADEME INT 5 C FR Research supporter

CNRS Nice ROR 2 P FR Scientific researchlaboratory

TNO ROR 6 P NL Research, developmentand consultancing

organismPolymage IND 1 P FR Engineering company

CSTB ROR 5 P FR research, technicalevaluation, and

regulation organismSOLE IND 2 P ES Manufacturer (glass

transformation)IST IND 1 P BE industrial company

(sputter coated flexiblesubstrates)

Bartenbach IND 2 P AT engineering consultingoffice

CNRS Toulouse ROR 3 P FR Scientific researchlaboratory

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JOE3-CT97-0068 EnerBuild RTD part.N°21- 2

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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JOE3-CT97-0068 EnerBuild RTD part.N°21- 3

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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JOE3-CT97-0068 EnerBuild RTD part.N°21- 4 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)• Response time (1/100 s)Reflective state : Broadness of the reflection1. Selective reflection (50 nm)2. Broadband reflection (150 nm)

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JOE3-CT97-0068 EnerBuild RTD part.N°21- 5

Results1 - 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 than100°C)

•Thanks to :• Optimisation of mixture formulations• Optimisation of polymerisation conditions

OFF-state : reflective OFF-state: one of the ON-state : scattering states transparent

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JOE3-CT97-0068 EnerBuild RTD part.N°21- 6

Results1 - ACTIVE FILM ELABORATION Selective film

Modification of the reflection wavelength

OFF-state Reflectance Transmittance

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JOE3-CT97-0068 EnerBuild RTD part.N°21- 7

Project Specifications1 - ACTIVE FILM ELABORATION Broadband film

The higher the broadness, the higher the light modulation is. ObjectiveBroadness expected in the proposal : 150 nm

Results• Several methods have been implemented

Obtained values : typical examplesWavelength =550 nm Broadness =200 nm Broad reflection to scattering state : reversibleBroad reflection to transparent state :

reversibility is to be improved (scattering)

• Wavelength = 1m Broadness =300 nmBroad reflection to scattering state : reversibleBroad reflection to transparent state : reversible

• Wavelength = 1.5 m Broadness = 400 nmBroad reflection to scattering state : reversibleBroad reflection to transparent state : reversible

Compromise about the reflection wavelength :•low (near 550nm) regarding the solar spectrum•high (favors the increase of the band broadness)

Energy Environment & Sustainable DevelopmentThematic Network on Energy in the Built Environment

JOE3-CT97-0068 EnerBuild RTD part.N°21- 82 - 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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JOE3-CT97-0068 EnerBuild RTD part.N°21- 9

ResultsELABORATION : GLAZED COMPONENT Project status : Increasing the sample size

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JOE3-CT97-0068 EnerBuild RTD part.N°21- 10JOE3-CT97-0068 EnerBuild RTD part.N°21- 10 Results

Project status : Example of characterisationSample HG 18 - Width 250nm- Mean wavelength 1.1 mVariation of solar and luminous transmittance as a function of voltage

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JOE3-CT97-0068 EnerBuild RTD part.N°21- 10

ELABORATION : GLAZED COMPONENT Project status : Example of characterisationSample HG 17- Width :70 nm-Mean wavelength 480nm Transmittance and reflectance as function of voltages and wavelengths

JOE3-CT97-0068 EnerBuild RTD part.N°21- 11

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JOE3-CT97-0068 EnerBuild RTD part.N°21- 12EVALUATION / 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 m. The wavelength broadness of the window is chosen successively between 150 and 500 nm,

nm, ml=545 nm100.0> > 0.2

nm, ml=525 nm100.0> > 60.7

Important solar transmittance modulation when the wavelength broadness of the window increases.

τ hn

v

/

τ hn

e

/

150 nm 200 nm 250 nm 500 nmMinimum value of

τn/hv %

5.6 1.3 0.2 0

Minimum value ofτn/h

e %

74.5 66.2 60.7 36.3

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JOE3-CT97-0068 EnerBuild RTD part.N°21- 12JOE3-CT97-0068 EnerBuild RTD part.N°21- 13

MARKET REQUIREMENT

Physicalproperty of

smartwindow

Application Comparison tothe state of art

Comments

Advantage Disadvant.Switchtransparent

Scattering

Switchableinterior wall

•Hightransmittance

in thescatteringstate

•Promisingsystem

• Low risk•Restricted

marketVisualprotectionsystem

• Easy tohandle

•Nomaintenance

Light.transmit in

. scat state ishigh(present

)samplesSwitch

transparent

Reflective

Switchablesunprotectionglazing

•Switchable- g value in

comparison tostatic sun

protectionglazing•Reflective

film incomparison to

absorbing.electrochrom

windows

•Coloringof

reflectedandtransmittedlight

•Incombination

with forexample

internal blinds all needs ofan office

rooms can befullilled•Promissingproperties•Highmarketvolume

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JOE3-CT97-0068 EnerBuild RTD part.N°21- 14

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 broadnessMarket 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 broadnessIndustrial : need of pre-industrial machine allowing film preparationMarket : Selective case : marketing approach

Broadband case : functional analysis