Modelling Indoor Illumination by Complex Fenestration Systems Based on Bidirectional Photometric Data
April 2005 - PDF 1.01MB
Significant efforts to assess the Bidirectional Transmittance distribution Functions (BTDFs) of complex fenestration systems (CFS) have been undertaken in recent years. This paper presents a methodology for including these bidirectional photometric raw data sets into the daylighting simulation and design process. The method is based on computing the luminous instensity distribution on internal façade elements from BTDF data (measured or calculated) and the outside luminance distribution on the façade elements. Special designed filters, which are necessary to pre-process the raw data, are derived. Since the BTDF raw data sets are big in volume, data compression techniques are introduced and applied. In order to account for dynamic – i.e. time variant systems – façade systems, like automated blinds, control models are being provided. The method is exemplarily incorporated into a complex fenestration system database and lighting simulation engines. The procedure is being validated. Limitations of the method are being discussed.