Electrochromic / Tinted Glazing:

Transcription

1 13th International Radiance Workshop 2014 London, UK 1-3 September 2014 Electrochromic / Tinted Glazing: Modelling the Illumination Spectrum John Mardaljevic Professor of Building Daylight Modelling School of Civil & Building Engineering Loughborough University, UK

2 Daylight illumination spectra

3 CCT 6803K : CRI Spectral Power [norm] Spectral Power [norm] CCT 4884K : CRI Spectral Power [norm] 0.8 Spectral Power [norm] CCT 4232K : CRI CCT 6844K : CRI CCT 6843K : CRI 93 CCT 5843K : CRI Spectral Power [norm] Spectral Power [norm] CCT 6468K : CRI 88 Spectral Power [norm] CCT 6283K : CRI Spectral Power [norm] Spectral Power [norm] CCT 7080K : CRI

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13 Transformations of daylight

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15 Spectral transmittance of the glazing panels SPD of light incident on the window SPD of light entering the space SPD of light recieved at points in the space

16 Spectral transmittance of the glazing panels SPD of light incident on the window SPD of light entering the space SPD of light recieved at points in the space

17 Spectral transmittance of the glazing panels SPD of light incident on the window SPD of light entering the space SPD of light recieved at points in the space

18 Spectral transmittance of the glazing panels SPD of light incident on the window SPD of light entering the space SPD of light recieved at points in the space

19 Spectral transmittance of the glazing panels SPD of light incident on the window SPD of light entering the space SPD of light recieved at points in the space Hypothesis

20 The dynamic control of daylight is the Holy Grail of the fenestration industry Steve Selkowitz, Lawrence Berkeley national Laboratory, CA, USA 1998 Image from Monty Python and the Holy Grail

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22 Image SAGE Electrochromics

23 Image SAGE Electrochromics

24 SAGE EC Transmission curves 62% 20% 6% 2% 0.6 Transmission UV INFRARED

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26 Arbitrary combinations of clear / tinted glass Incident Light

27 Create a spectral transmission model for the combination Incident Light Transmitted Light

28 V = V a V b V c V d = % 20% 6% 2% R = N a N b N c N d = Va V b V c V d Na N b N c N d > V R = (N a + N b + N c + N d ) V R = V R> P R

29 Vector of transmission values [300nm - 2,500nm] for EC glazing in one state of tint T a = t a1 t a2 t am Matrix of transmission values for EC glazing in four states of tint 2 3 T a 6T b = T c T d 2 3 t t t a1 a2 am 6t t t b1 b2 bm 7 4t t t 5 c1 c2 cm t d1 t d2 t dm

30 For any arbitrary combination R of EC glazing in tint states a, b, c and d, the effective spectral transmission curve for the ensemble is: T R = R T a T b T c T d > P R T R = t R1 t R2 t Rm

31 Effective transmission of ensemble = : % of transmitted light from clear state = 96% T_vis [ ] in ratio [ ] 1.0 2% 62% 0.8 Combination Transmission (Tmax=1) V ( ) Combination relative to clear % 2%

32 Effective transmission of ensemble = : % of transmitted light from clear state = 93% T_vis [ ] in ratio [ ] Transmission (Tmax=1) % 2%

33 Effective transmission of ensemble = : % of transmitted light from clear state = 91% T_vis [ ] in ratio [ ] Transmission (Tmax=1) % 2%

34 Effective transmission of ensemble = : % of transmitted light from clear state = 88% T_vis [ ] in ratio [ ] Transmission (Tmax=1) % 2%

35 Effective transmission of ensemble = : % of transmitted light from clear state = 86% T_vis [ ] in ratio [ ] Transmission (Tmax=1) % 2%

36 Effective transmission of ensemble = : % of transmitted light from clear state = 83% T_vis [ ] in ratio [ ] Transmission (Tmax=1) % 2%

37 Effective transmission of ensemble = : % of transmitted light from clear state = 81% T_vis [ ] in ratio [ ] Transmission (Tmax=1) % 2%

38 Effective transmission of ensemble = : % of transmitted light from clear state = 79% T_vis [ ] in ratio [ ] Transmission (Tmax=1) % 2%

39 1 Clear panel full tint 1.0 Transmittance (normalised)

40 Validation Scenario: The De Montfort EC Office Study

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42 Methodology Compare predicted spectrum with measurements of the daylight spectrum taken at six points in a room with EC glazing for various combinations of tint state. Measurements taken under sunny conditions. Spectra normalised to the same effective lux value.

43 D F C zone 7 zone 5 zone 8 zone 6 zone 9 A B E

44 Spectral Power [normalised] D75 D65 D55 V-lambda 0

45 Incident Light Transmitted Light D 55 T R = Illumination spectrum

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47 1.5 Theory [D55] Measured R = [ ] T vis = 0.25 : P clear = 94% CCT mean = 4970K : CRI mean = 93 Spectral power [normalised] r mean =

48 1.5 Theory [D55] Measured R = [ ] T vis = 0.09 : P clear = 81% CCT mean = 4800K : CRI mean = 94 Spectral power [normalised] r mean =

49 1.5 Theory [D55] Measured R = [ ] T vis = 0.36 : P clear = 65% CCT mean = 5211K : CRI mean = 92 Spectral power [normalised] r mean =

50 1.5 Theory [D55] Measured R = [ ] T vis = 0.27 : P clear = 86% CCT mean = 5243K : CRI mean = 93 Spectral power [normalised] r mean =

51 1.5 Theory [D55] Measured R = [ ] T vis = 0.09 : P clear = 0% CCT mean = 6845K : CRI mean = 87 Spectral power [normalised] r mean =

52 1.5 Theory [D55] Measured R = [ ] T vis = 0.03 : P clear = 0% CCT mean = 11557K : CRI mean = 84 Spectral power [normalised] r mean =

53 R Measured Measured r mean N62 N 20 N 06 N 02 CCT mean CRI mean D 55 (D 65,D 75 ) K (0.875, 0.760) 5243 K (0.902, 0.782) 4970 K (0.919, 0.794) 4800 K (0.700, 0.514) 6845 K (0.917, 0.862) K (0.947, 0.916)

54 Wot, no Radiance?

55 9m x 9m T vis = 2% T vis = 62%

56 T vis = 62% T vis = 2% lux 63 lux 15 lux lux 184 lux ab 1

57 T vis = 62% T vis = 2% lux 540 lux 19 lux lux 195 lux ab 7

58 % contribution from clear state 79 % % % ab 1

59 % contribution from clear state 96 % % % ab 7

60 SAGE White Paper: How to Maintain Neutral Daylight Illumination with SageGlass Electrochromic Glazing Neutral daylight illumination with variable transmission glass: Theory and validation. J. Mardaljevic, R. Kelly Waskett, and B. Painter. Accepted for publication in Lighting Research and Technology.

61 Acknowledgements: Dr. Birgit Painter & Ruth Kelly De Montfort University, Leicester, UK Dr. Helen Sanders SAGE Electrochromics Inc, MN, US Thank you John Mardaljevic links: Staff page CBDM Professor of Building Daylight Modelling School of Civil & Building Engineering Loughborough University, UK Loughborough University