02077nas a2200229   4500000000100000008004100001260007300042653000900115653001400124653002200138653002000160653001500180653001500195653001800210100001500228700002100243700002600264700001800290700001500308245013600323520138800459       2010                            d  c05/2010bThe International Society for Optical EngineeringaBrussels10aBSDF10abuildings10aenergy efficiency10agoniophotometry10areflection10ascattering10atransmittance1 aLars Grobe1 aStephen Wittkopf1 aPeter Apian-Bennewitz1 aJacob Jonsson1 aMike Rubin00aExperimental validation of bidirectional reflection and transmission distribution measurements of specular and scattering materials3 aThe development of advanced materials for facades aims to achieve higher energy efficiency of buildings. Successful application of these materials depends on the availability of reliable characterization data. While data derived from integrated measurements of transmission and reflection is widely available, it does not allow to characterize the angular dependence of the performance of such materials. The Bidirectional Reflection-Transmission Distribution (BRTD) can be measured by commercially available Gonio-Photometers and, complimenting integrated transmittance and reflectance, allows the assessment of facade materials and thus supports both their development and application. Validation of the obtained data is crucial to back these measurements. Integration of validation procedures into the operation of a characterization laboratory allowing a well-defined approach to quality control is presented for a range of typical material and sample types:
- consistency checks of measurement data
- cross-checking of integrated material properties derived from BRTD data with integrating sphere measurements
- round-robin comparison between laboratories using comparable devices
The results of of these first measurements are discussed. Potential to further improve the availability of reliable angular resolved characterization data for the building sector is identified.