Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment JOE3-CT EnerBuild RTD part.N°21- SMART WINDOW : POLYMER NETWORK LIQUID CRYSTAL WITH REFLECTIVE, SCATTERING AND CLEAR STATE Co-ordinator : Marc Casamassima ADEME Sophia-Antipolis 500 route des Lucioles Valbonne - France Presenter : Pierre Sioux LPMC-UMR 6622 CNRS-Université de Nice Parc valrose Nice - France

Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment JOE3-CT EnerBuild RTD part.N°21- 1

Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment JOE3-CT 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.

Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment JOE3-CT 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

Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment JOE3-CT 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 reflection 1. Selective reflection (50 nm) 2. Broadband reflection (150 nm)

Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment JOE3-CT EnerBuild RTD part.N°21- 5 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 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

Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment JOE3-CT EnerBuild RTD part.N°21- 6 Results 1 - ACTIVE FILM ELABORATION Selective film Modification of the reflection wavelength OFF-state Reflectance Transmittance

Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment JOE3-CT EnerBuild RTD part.N°21- 7 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 = 1  mBroadness =300 nm Broad reflection to scattering state : reversible Broad reflection to transparent state : reversible Wavelength = 1.5  mBroadness = 400 nm Broad reflection to scattering state : reversible Broad 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 Development Thematic Network on Energy in the Built Environment JOE3-CT EnerBuild RTD part.N° 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

Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment JOE3-CT EnerBuild RTD part.N°21- 9 Results ELABORATION : GLAZED COMPONENT Project status : Increasing the sample size

Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment JOE3-CT EnerBuild RTD part.N° Results Project status : Example of characterisation Sample HG 18 - Width 250nm- Mean wavelength 1.1  m Variation of solar and luminous transmittance as a function of voltage

Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment JOE3-CT EnerBuild RTD part.N° 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 JOE3-CT EnerBuild RTD part.N°21- 11

Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment JOE3-CT EnerBuild RTD part.N° 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  m. The wavelength broadness of the window is chosen successively between 150 and 500 nm,  nm, ml =545 nm 100.0> > 0.2  nm, ml =525 nm 100.0> > 60.7 Important solar transmittance modulation when the wavelength broadness of the window increases.

Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment JOE3-CT EnerBuild RTD part.N° JOE3-CT EnerBuild RTD part.N° MARKET REQUIREMENT

Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment JOE3-CT EnerBuild RTD part.N° 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