Fritted Glass TG – Spring 2016 Jacob C. Jonsson Windows and Envelope Materials Group Building Technology and Urban Systems Division
SCOPE and Members Find a way to obtain spectral data for fritted glass in a manner that would allow WINDOW calculations of IGUs. Determine best practice how to obtain data and verify the accuracy of these practices. TG: Jason Theios, Dan Wacek, Jacob Jonsson, Helen Rose Wilson, Mike Buchanan, Ben West, Michael Hawkings, David Cooper, Joe Richard, Mike Thoman, Paul Bush, Jen Padgett 2
Get scattering samples with a trusted result Started with fritted glass, but sample inhomogeneity made it hard to get repeatable measurement results Viracon fabricated three laminates with a diffuse interlayer each at 11.75" x 7.75" with tin surfaces to be exposed. 12 mm OptiWhite (low iron)+0.030“ Saflex Arctic Snow (transluscent white)PVB+3 mm Optiwhite float glass High transmittance, VT~0.65, R & A ~
Instrument parameters Guardian 270 mm integrating sphere, special designed attachment for Perkin-Elmer 1050 spectrophotometer 100 mm aperture Beam size ~ 10 mm by 20 mm Can measure oblique angles of incidence as well as at near normal 4
Transmittance at 8 degrees angle of incidence Both R and T were measured at 8 degrees angle of incidence to get accurate absorption calculations 10mm expected to be lower, longer travel more light loss 5
Reflectance at 8 degrees angle of incidence I would have expected 10mm to be lower here but it is higher for all samples Longer distance would increase glass absorption and larger light loss L2 higher for both R and T 6
Absorption (+ light loss) based on orientation - vis Absorption 3 mm was based on T measurement orientation, i.e. A3mm = 1-T3mm-R10mm Since R3mm A3mm 7
Absorption (+ light loss) based on orientation - NIR Difference decreases with longer wavelengths Would be consistent with reduction in scattering and less light loss and less glass absorption 8
Next Step Jason Theios (Guardian) to send samples to labs. LBNL and Fraunhofer ISE to measure L1 and L3 using goniophotometers Compare goniophotometer data with spectrophotometer data Optimistic goal to have something in 2 months 9