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Measuring Optical Properties of Fenestration Systems to Optimize Performance and Enable Simulation. Nick Gayeski, Kellie Stokes. Advanced Window Systems Increasing and Evolving How to Describe and Predict Dynamic Performance?. Describing Performance NFRC rating is lacking… .
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Measuring Optical Properties of Fenestration Systems to Optimize Performance and Enable Simulation Nick Gayeski, Kellie Stokes
Advanced Window Systems • Increasing and Evolving • How to Describe and Predict Dynamic Performance?
Describing Performance • NFRC rating is lacking… New metrics are under development
Predicting Performance Spectral, Bidirectional Transmission and Reflection Fenestration System Properties & Thermal Properties Tool for calculating total window thermal performance Simulation of electric and day light Window 5.x DElight Whole building energy simulation Complex fenestration systems (CFS) mean data rich simulation requirements
Goniophotometer (angle-light-meter): Tool for measuring BT(R)DFs F’ F
Extracting BT(R)DFs from a digital camera • Pixel value Radiance • Pixel location Emerging Angle • Pixel group Solid Angle • Spatial Calibration
Spectroradiometric calibration • How to do it? • Camera response function • Spectral sensitivity R = 155 λ = 550 nm integration time = 500 ms 2 microWatts/cm2-sr of monochromatic light
Mixing monochromatic beams • How to measure beams with arbitrary spectra?
? Estimating the full spectrum Total energies in each interval
sample reflection R: .45 G: .025 B: .075 Camera sensitivity R: .2 G: .95 B: .15 Estimating the full spectrum Using RGB channel sensitivity
Camera sensitivity R: 2.0 G: 9.5 B: 1.5 sample reflection R: 4.5 G: .25 B: .75 Estimating the full spectrum RGB channel sensitivity
The Process…. Spatial Calibration Spectroradiometric calibration Spectrum estimation methods BT(R)DF !!
Summary Advanced Systems Better Performance Describe Simulate New Information: BT(R)DF Better Measurement and AnalysisTools