Electrochromic Materials and their Characterization by Solar Radiation Glazing Factors for Smart Window Applications

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1 Electrochromic Materials and their Characterization by Solar adiation Glazing Factors for Smart Window Applications Bjørn Petter Jelle ab, Tao Gao c, Yingpeng Zhen b and Arild Gustavsen c a SINTEF Building and Infrastructure, Department of Materials and Structures, NO-7465 Trondheim, Norway. b Norwegian University of Science and Technology (NTNU), Department of Civil and Transport Engineering, NO-749 Trondheim, Norway. c Norwegian University of Science and Technology (NTNU), Department of Architectural Design, History and Technology, NO-749 Trondheim, Norway. A Workshop of Building Efficiency, Peder Sather Center for Advanced Study, University of California Berkeley, Berkeley, U.S.A., 5 September, 04.

2 Electrochromic windows (ECWs) egulates solar radiation by application of an external voltage. May decrease heating, cooling and electricity loads in buildings. Dynamic and flexible solar radiation control. May be characterized by a number of solar radiation glazing factors.

3 Glass - Solar adiation Solar Spectrum nm Solar Ultraviolet (UV) nm Visible Light (VIS) nm Near Infrared (NI) nm AM0 (outer space) AM (earth s surface, the sun 30º above the horizon) Molecular absorption (in O, O 3, H O and CO ) edrawn from: A.L. Fahrenbruch and.h. Bube, Fundamentals of solar cells. Photovoltaic solar energy conversion, pp. 6-3, Academic Press, 983. Glass A Marvellous Material 3

4 Glass Solar adiation Window Panes Solar adiation through Window Panes and other Glass Structures T() + A() + () = (00 %) and E() = A() Incident Light A E = A T T + A + = T T A T A T T T T T A T A T and so on T A T A T T T T T T 4

5 Solar adiation through Window Panes and other Glass Structures T T A T A T T T T T A T A T and so on Single Glass Pane T( ) ( ) T T A T A T T T T T T int ext Two-Layer Window Pane ext T( ) int ( ) TT ( ) b Three-Layer Window Pane T( ) ( ) ( ) [ 3b b b T b T b T T ][ b b T 3 T [ b [ ][ T3 [ 3 b [ b 3 ][ b ] T b 3 b 3 ] T ] T b b T ] T 3 T ] T 3 3 b b 3 3 b 5

6 Solar adiation Glazing Factors Generally, the most important solar radiation glazing factors are: Ultraviolet Solar Transmittance, T uv Visible Solar Transmittance, T vis Solar Transmittance, T sol Solar Material Protection Factor, SMPF Solar Skin Protection Factor, SSPF External Visible Solar eflectance, vis,ext Internal Visible Solar eflectance, vis,int Solar eflectance, sol Solar Absorbance, A sol Emissivity, Solar Factor, SF Colour endering Factor, CF 6

7 Glass Solar adiation Window Panes Solar adiation through Window Panes and other Glass Structures The Solar Transmittance (T sol ) is given by the following expression: T sol 500nm T( )S 300nm 500nm S 300nm S = relative spectral distribution of solar radiation T() = spectral transmittance of the glass = wavelength = wavelength interval S values at different wavelengths are given in a table 7

8 Solar adiation Glazing Factor Definitions Ultraviolet Solar Transmittance (T uv ) T uv 380nm 300nm 380nm T( )S S 300nm Visible Solar Transmittance (T vis ) (Light Transmittance) T vis 780nm 380nm 780nm T( )D D 380nm V( ) V( ) Solar Transmittance (T sol ) T sol 500nm T( )S 300nm 500nm S 300nm 8

9 Solar adiation Glazing Factor Definitions Solar Material Protection Factor (SMPF) SMPF df 600 nm 300 nm 600 nm T( )C C 300 nm S S Solar Skin Protection Factor (SSPF) B. P. Jelle, A. Gustavsen, T.-N. Nilsen and T. Jacobsen, Solar Material Protection Factor (SMPF) and Solar Skin Protection Factor (SSPF) for Window Panes and other Glass Structures in Buildings, Solar Energy Materials & Solar Cells, 9, , 007. SSPF F sd 400nm 300nm 400nm T( )E E 300nm S S 9

10 Solar adiation Glazing Factor Definitions External Visible Solar eflectance ( vis,ext ) (External Light eflectance) 780nm Internal Visible Solar eflectance ( vis,int ) (Internal Light eflectance) vis,ext ext 380nm 780nm 380nm ( )D D V( ) V( ) Solar eflectance ( sol ) vis,int 780 nm int 380 nm 780 nm 380 nm ( )D D V( ) V( ) sol 500nm ext 300nm 500nm 300nm ( )S S 0

11 Solar adiation Glazing Factor Definitions Solar Absorbance (A sol ) A sol T sol sol 500nm T( )S 300nm 500nm S 300nm 500nm ext 300nm 500nm 300nm ( )S S B. P. Jelle, Solar adiation Glazing Factors for Window Panes, Glass Structures and Electrochromic Windows in Buildings - Measurement and Calculation, Solar Energy Materials and Solar Cells, 6, 9-33, 03.

12 Solar adiation Glazing Factor Definitions Emissivity () Specular I reflectance measurements c 30 corr n n c corr ( n ) c corr n ( i ) n 30 i Heat flow meter measurements 4T (q 3 m tot T q d tot T) T Total hemispherical emissivity (Hemispherical reflectometer and integrating over the hemisphere) / 0 t ( ) sin cos d d t (,, ) 0 ( )P(, T)d 0 P(, T)d P 8hc (, T) 5 hc /( kt (e ) )

13 Solar adiation Glazing Factor Definitions Solar Factor (SF) Total Solar Energy Transmittance Solar Heat Gain Coefficient (SHGC) g-value SF = T sol + q i q i = secondary heat transfer factor towards the inside Colour endering Factor (CF) Further details in ISO/FDIS 9050:003(E), ISO 09:994(E), EN-ISO 6946:996 and EN 40:998 E CF a i i i =00-4.6E i = specific colour rendering index E * * * * * * i (U t,i U r,i ) (Vt,i Vr,i ) (Wt,i Wr,i ) = total distortion of colour i 3

14 where = wavelength (nm) Solar adiation Glazing Factor Definitions = wavelength interval (nm) T() = spectral transmittance of the glass ext () = external spectral reflectance of the glass int () = internal spectral reflectance of the glass n = average spectral reflectance calculated by summation of spectral reflectance values at 30 distinct wavelengths and divided by 30 as shown in Eq.0 above i = wavelength and i values for the 30 wavelengths are given in ISO 09:994(E) and EN 898:00 E S = relative spectral distribution of ultraviolet solar radiation or solar radiation (ISO/FDIS 9050:003(E), ISO 9845-:99(E)) D = relative spectral distribution of illuminant D65 (ISO/FDIS 9050:003(E), ISO 056:999(E)) V() = spectral luminous efficiency for photopic vision defining the standard observer for photometry (ISO/FDIS 9050:003(E), ISO/CIE 057:99(E)) S values at different wavelengths for ultraviolet solar radiation or solar radiation are given in ISO/FDIS 9050:003(E) D V() values at different wavelengths are given in ISO/FDIS 9050:003(E) df = CIE damage factor (ISO/FDIS 9050:003(E), CIE No 89/3:990) C = e -0.0 ( given in nm) C S values at different wavelengths are given in ISO/FDIS 9050:003(E) F sd = skin damage factor (ISO/FDIS 9050:003(E), McKinlay and Diffey 987) E = CIE erythemal effectiveness spectrum E S values at different wavelengths are given in ISO/FDIS 9050:003(E) q tot = total heat flow density between two parallel, flat infinite isothermal surfaces (W/m ) (EN 946-:999 E, EN 946-3:999 E) = thermal conductivity of the medium separating the two surfaces (W/(mK)) = air = ( ) (W/(mK)) (values accurate to 0.6 % between = 0ºC and = 70ºC) ( given in ºC) (EN 946-:999 E, EN 946-3:999 E) = (T m K)ºC/K (ºC) T m = mean temperature of the two surfaces (K) T = temperature difference between the two surfaces (K) d = distance between the two surfaces (m) = k 4 /(60ħ 3 c ) = Stefan-Boltzmann s constant W/(m K 4 ) 4 ( )P(, T)d 0 (,, ) (Surface Optics Corporation 009) t 0 P(, T)d P 8hc (, T) = Planck s function (Surface Optics Corporation 009) 5 hc /( kt (e ) ) = hemispherical reflectance T = temperature (K) and are integrating angles over the hemisphere h = Planck s constant Js k = Boltzmann s constant J/K c = velocity of light m/s T sol = solar transmittance (Eq.3) A sol = q i + q e (A sol from Eq.9) q i = secondary heat transfer factor towards the inside q e = secondary heat transfer factor towards the outside (complete details for calculation of SF given in ISO/FDIS 9050:003(E), with additions in ISO 09:994(E) and EN-ISO 6946:996, note that and sol enter into q i in Eq., sol from A sol ) a = 8 8 i i = general colour rendering index (EN 40:998 E) i = E i = specific colour rendering index * * * * * * E i (U t,i U r,i ) (Vt,i Vr,i ) (Wt,i Wr,i ) = total distortion of colour i (complete details for calculation of CF given in EN 40:998 E)

15 Solar Factor (SF) for Single Glazing SF T sol q i T sol A sol h e h i h i T sol = solar transmittance (Eq. 3) sol = solar reflectance (Eq. 8) A sol = - T sol - sol = solar absorbance (Eq. 9 and Eq. 0) h e = 3 W/(m K) (Eq. 44, see applicable assumptions) h i W /(m K) (Eq. 45, see applicable assumptions) = corrected emissivity of the inside surface 5

16 Solar Factor (SF) for Double Glazing SF T sol q i T sol A sol, h h i e A sol, h e A sol, A sol, 500 nm b A 300 nm b 500 nm A S 300 nm T S = thermal conductance between the outer surface of the outer (first) pane and the innermost surface of the inner (second) pane A sol, 500 nm A T 300 nm b 500 nm S 300 nm S A = - T - A b = - T - b A = - T - 6

17 A A A SF sol, sol, sol,3 T sol Solar Factor (SF) for Triple Glazing q i T A T sol ( 300 nm A sol, A h sol, 500 nm b b 3 b 3 A 300 nm ( b )( b 3 ) T b nm T A ( 500 nm S 300 nm ) T T 500 nm b 3 b nm ( b )( b 3) T b 3 S T T 300 nm ) T T A 500 nm nm ( b )( b 3 ) T b nm S A A e S S 7 h i S A sol,3 h e A sol, A 3 sol,3 A sol,3 3 = thermal conductance between the outer surface of the outer (first) pane and the centre of the middle (second) pane 3 = thermal conductance between the centre of the middle (second) pane and the centre of the inner (third) pane A = - T - (Eq. 7) A b = - T - b (Eq. 7) A = - T - (Eq. 73) A b = - T - b A 3 = - T 3-3

18 Solar Factor (SF) for Multiple Glazing SF = T sol + q i q i A sol, A sol, A h e sol,3... A h sol,n i h e A sol, A sol, A... sol,n (n)n A sol, A sol,n A sol,n (n)n U h e h i N h s M d m r m 8

19 Float Glass Solar adiation through Window Panes and other Glass Structures Transm. / Absorb. / eflect Float Glass Transmittance Absorbance eflectance Transmittance Absorbance eflectance Wavelength (nm) 9

20 Low Emittance Coated Glass Solar adiation through Window Panes and other Glass Structures Transm. / Absorb. / eflect Glass with Low Emittance Coating Absorbance eflectance Transmittance Transmittance Absorbance eflectance Wavelength (nm) 0

21 Dark Silver Coated Glass Solar adiation through Window Panes and other Glass Structures Transm. / Absorb. / eflect Silver Coated Glass eflectance Absorbance Transmittance Transmittance Absorbance eflectance Wavelength (nm)

22 Float Low Emittance Dark Silver Solar adiation through Window Panes and other Glass Structures Transm. / Absorb. / eflect. Transm. / Absorb. / eflect Float Glass Transmittance Absorbance eflectance Transmittance Absorbance eflectance Wavelength (nm) Glass with Low Emittance Coating Absorbance eflectance Transmittance Transmittance Absorbance eflectance Transm. / Absorb. / eflect Silver Coated Glass eflectance Absorbance Wavelength (nm) Transmittance Transmittance Absorbance eflectance Wavelength (nm)

23 Solar adiation Glazing Factors for Miscellaneous Glass (Float Low Emittance Dark Silver) Glass Configuration n T uv T vis T sol SMPF SSPF vis,ext vis,int sol A sol SF CF Float Glass G Low Emittance Glass LE/G Dark Silver Glass S/G

24 Solar adiation Glazing Factors for Miscellaneous Glass Solar adiation through Window Panes and other Glass Structures Glass Configuration n T uv T vis T sol SMPF SSPF vis,ext vis,int sol A sol SF CF Float Glass G Low Emittance Glass LE/G Dark Silver Glass S/G Float/Float G/A/G Float/LowE G/A/LE/G Float/Silver G/A/S/G LowE/LowE G/LE/A/LE/G LowE/Float G/LE/A/G Silver/Float G/S/A/G Silver/LowE G/S/A/LE/G Silver/Silver G/S/A/S/G Float/Float/Float G/A/G/A/G Float/Float/LowE G/A/G/A/LE/G Float/LowE/LowE G/A/LE/G/A/LE/G

25 Solar adiation Glazing Factors for Miscellaneous Glass Solar adiation through Window Panes and other Glass Structures Glass Configuration n T uv T vis T sol SMPF SSPF vis,ext vis,int sol A sol SF CF Float Glass G Low Emittance Glass LE/G Dark Silver Glass S/G Float/Float G/A/G Float/LowE G/A/LE/G Float/Silver G/A/S/G LowE/LowE G/LE/A/LE/G LowE/Float G/LE/A/G Silver/Float G/S/A/G Silver/LowE G/S/A/LE/G Silver/Silver G/S/A/S/G Float/Float/Float G/A/G/A/G Float/Float/LowE G/A/G/A/LE/G Float/LowE/LowE G/A/LE/G/A/LE/G LowE/LowE/LowE G/LE/A/LE/G/A/LE/G Silver/Float/Float G/S/A/G/A/G Silver/Float/LowE G/S/A/G/A/LE/G Silver/LowE/LowE G/S/A/LE/G/A/LE/G Silver/Silver/Silver G/S/A/S/G/A/S/G

26 Float Glass Number of Window Panes Solar adiation through Window Panes and other Glass Structures Transmittance Float Glass:, and 3 Layer Window Pane Wavelength (nm) 6

27 Smart Windows Electrochromic Window Configurations Applied voltage Applied voltage Glass PAMPS Glass Light Glass PAMPS Glass Light Indium-tin oxide Indium-tin oxide Indium-tin oxide Indium-tin oxide Polyaniline Tungsten oxide Polyaniline Tungsten oxide Prussian blue Prussian blue Window configuration ECW Window configuration ECW (PANI-PB multilayer) 7

28 Smart Windows Electrochromic Materials and Chemical eactions PANI, PB and WO 3 (transparent) WO 3 + (PANI)(yH + A - ) + (x-y)k Fe II [Fe(CN) 6 ] + (x-y)h + H x WO 3 + (PANI y+ )(A - ) y + (x-y)kfe III [Fe(CN) 6 ] + (x-y)k + (blue) Applied voltage y = x Glass PAMPS Glass Light PANI and WO 3 Indium-tin oxide Polyaniline Prussian blue Indium-tin oxide Tungsten oxide WO 3 + (PANI)(xH + A - ) H x WO 3 + (PANI x+ )(A - ) x (transparent) (blue) 8

29 Spectroscopical Data for Electrochromic Windows Applied voltage Window configuration ECW.0 PAMPS Glass Glass Light Indium-tin oxide Indium-tin oxide Polyaniline Tungsten oxide Prussian blue Transmittance Glass/ITO/PANI/PB/PAMPS/WO 3 /ITO/Glass mv 0 mv + 00 mv mv mv +00 mv +400 mv Wavelength (nm) 9

30 Spectroscopical Data for Electrochromic Windows Window configuration ECW (PANI-PB multilayer) Applied voltage Glass Indium-tin oxide Polyaniline Prussian blue PAMPS Glass Light Indium-tin oxide Tungsten oxide Transmittance Glass/ITO/PANI-PB/PAMPS/WO 3 /ITO/Glass mv +00 mv Wavelength (nm) 30

31 Spectroscopical Data for Electrochromic Windows Applied voltage Window configuration ECW3 Glass Indium-tin oxide PAMPS Glass Light Indium-tin oxide Polyaniline Tungsten oxide Prussian blue Transmittance ECW3 Glass/ITO/PANI/PB/PAMPS/WO 3 /ITO/Glass mv 0 mv mv mv +400 mv Wavelength (nm) 3

Spectral Changes in Polyaniline (PANI) Transparent Yellow Green Blue Violet 0.4 PANI + 800 mv + 700 mv + 600 mv + 500 mv + 400 mv + 300 mv + 00 mv + 00 mv - 400 mv + 800 0. 0.0 0.8 + 300 + 00 + 400 0.

32 Spectral Changes in Polyaniline (PANI) Transparent Yellow Green Blue Violet 0.4 PANI mv mv mv mv mv mv + 00 mv + 00 mv mv PANI Wavelength (nm) PANI may exhibit many colours PANI doping: 000 log0(/t) ) Absorbance ( Absorbance (log0(i0/i)) V) (m Wa 0 l 600 a vel ti n -00 eng 700 e 800 ot th -400 P (nm 900 ) edox processes Proton doping 3

33 Transmittance Glass/ITO/PANI/PB/PAMPS/WO 3/ITO/Glass mv 0 mv mv mv mv mv mv Solar adiation Modulation by ECWs Wavelength (nm) Transmittance 0 adjustable T A Transmittance 0 adjustable T Transmittance 0 adjustable T A T Wavelength Wavelength Wavelength Absorbance (A) egulating eflectance () egulating Combined A and egulating A adjustable Absorbance 0 adjustable eflectance 0 Absorbance, eflectance 0 adjustable A Wavelength Wavelength p =c / p = (c/q e )(m e 0 /n e ) / Wavelength 33

34 Solar adiation Glazing Factors for Electrochromic Windows Glass Configuration n T uv T vis T sol SMPF SSPF vis,ext vis,int sol A sol SF CF ECW (-800 mv) ECW (0 mv) ECW (+00 mv) ECW (+500 mv) ECW (+800 mv) ECW (+00 mv) ECW (+400 mv) ECW (-800 mv) ECW (+00 mv) ECW3 (-800 mv) ECW3 (+400 mv)

35 Solar adiation Glazing Factors for Electrochromic Windows Glass Configuration n T uv T vis T sol SMPF SSPF vis,ext vis,int sol A sol SF CF ECW (-800 mv) ECW (0 mv) ECW (+00 mv) ECW (+500 mv) ECW (+800 mv) ECW (+00 mv) ECW (+400 mv) ECW (-800 mv) ECW (+00 mv) ECW3 (-800 mv) ECW3 (+400 mv) EC/Float (-) ECT/A/G EC/Float (+) ECC/A/G EC/LowE (-) ECT/A/LE/G EC/LowE (+) ECC/A/LE/G EC/Float/Float (-) ECT/A/G/A/G EC/Float/Float (+) ECC/A/G/A/G EC/Float/LowE (-) ECT/A/G/A/LE/G EC/Float/LowE (+) ECC/A/G/A/LE/G EC/LowE/LowE (-) ECT/A/LE/G/A/LE/G EC/LowE/LowE (+) ECC/A/LE/G/A/LE/G EC/LowE/LowE (-) ECT/A/LE/G/A/LE/G EC/LowE/LowE (+) ECC/A/LE/G/A/LE/G

36 Solar adiation Glazing Factor Modulation for Electrochromic Windows Glass Configuration n T uv T vis T sol SMPF SSPF vis,ext vis,int sol A sol SF CF ECW (-800 mv) ECW (+400 mv) ECW (-800 mv) ECW (+00 mv) ECW3 (-800 mv) ECW3 (+400 mv) EC/Float (-) ECT/A/G EC/Float (+) ECC/A/G EC/LowE (-) ECT/A/LE/G EC/LowE (+) ECC/A/LE/G EC/Fl /Fl ( )

37 Solar adiation Glazing Factor Modulation for Electrochromic Windows Glass Configuration n T uv T vis T sol SMPF SSPF vis,ext vis,int sol A sol SF CF ECW (-800 mv) ECW (+400 mv) ECW (-800 mv) ECW (+00 mv) ECW3 (-800 mv) ECW3 (+400 mv) EC/Float (-) ECT/A/G EC/Float (+) ECC/A/G EC/LowE (-) ECT/A/LE/G EC/LowE (+) ECC/A/LE/G EC/Float/Float (-) ECT/A/G/A/G EC/Float/Float (+) ECC/A/G/A/G EC/Float/LowE (-) ECT/A/G/A/LE/G EC/Float/LowE (+) ECC/A/G/A/LE/G EC/LowE/LowE (-) ECT/A/LE/G/A/LE/G EC/LowE/LowE (+) ECC/A/LE/G/A/LE/G EC/LowE/LowE (-) ECT/A/LE/G/A/LE/G EC/LowE/LowE (+) ECC/A/LE/G/A/LE/G

38 ECW with Float Glass Number of Window Panes Applied voltage Window configuration ECW PAMPS Glass Glass Light Indium-tin oxide Indium-tin oxide Polyaniline Tungsten oxide Prussian blue.0 Transmittance ECW with Float Glass:, and 3 Layer Window Pane mv +400 mv Wavelength (nm) 38

39 Solar adiation Glazing Factors Article addressing the solar radiation glazing factors 39

40 Properties, equirements and Possibilities Smart Windows A State-of-the-Art eview 40

41 Fenestration of Today and Tomorrow: A State-of-the-Art eview and Future esearch Opportunities 4

42 Commercial Electrochromic Windows Some Company Examples: SAGE Electrochromics (USA) EControl-Glas (Germany) GESIMAT (Germany) ChromoGenics (Sweden) 4

43 Commercial Electrochromic Windows Transparent Dark Intermediate 43

44 Commercial Electrochromic Windows Coloured Transparent 44

45 Commercial Electrochromic Windows Coloured Transparent 45

46 Commercial Electrochromic Windows Coloured Transparent 46

47 Commercial Electrochromic Windows Coloured Transparent 47

48 Commercial Electrochromic Windows 48

49 Commercial Electrochromic Windows Coloured Transparent 49

50 Conclusions Electrochromic Windows Enable a dynamic control of the solar radiation radiation throughput in windows. May readily be characterized by solar radiation glazing factors. Applied voltage.0 Transmittance Glass/ITO/PANI/PB/PAMPS/WO 3 /ITO/Glass mv 0 mv + 00 mv mv mv +00 mv +400 mv Glass Indium-tin oxide PAMPS Glass Light Indium-tin oxide Wavelength (nm) Polyaniline Prussian blue Tungsten oxide 50

51 Solar radiation dynamically controlled by electrochromic windows and characterized by solar radiation glazing factors 5

Glazing selection for solar design

Glazing selection for solar design Visible light transmittance: A measure of the amount of visible light that passes through the glazing material of a window, door, or skylight. Visible light transmittance,