The photometry of optical daylighting systems is best described with Bi-directional Scatter Distribution Function (BSDF) files that describe in simple terms the distribution of outgoing light relative to the direction of incoming light. This BSDF file is in the standard XML file format that is used by the Lawrence Berkeley National Laboratories (LBNL) Window 7.X software that utilizes the growing Complex Glazing Data Base (CGBD) as well as the standard format used in the Radiance software. Two files are provided, one at a lower standard Klems (145 patch) resolution and one with a 4x higher density variable resolution. The standard Klems file is adequate for analyzing the workplane performance of a LightLouver installation or the general light in the space. However, if glare or detailed rendering and luminance based analysis is performed, the higher density variable resolution file must be used as it better describes LightLouvers unique and impressive ability to direct the outgoing light precisely above the horizontal direction. When using either file in the Radiance software, care must be taken to use appropriate Radiance parameters to properly sample the large amount of light coming from the LightLouver units. In particular care must be taken in setting the ambient settings, at a minimum use: -ad of 4096 or higher, -ar of 60 (and adequate for detail in scene), -ab 3 or higher.
Right click and select "save link-as" to download file to your computer. The Klems file is already built-in and provided with the SPOT Pro software which makes daylighting analysis a breeze.
IES Photometric Files
Photometric files for the LightLouver Daylighting System in the Illumination Engineering Society of North America (IESNA) standard (*.ies) format have been created for many project locations. These IES photometric files can be used in static lighting simulation tools to model the daylighting performance of the LightLouver Daylighting System.
IES files are available in 5o increments up to 60o latitude. The following table provides links to download the IES photometric files for the corresponding latitude:
Instructions for using the LightLouver IES photometric files are presented below. These instructions are also downloadable here.
The photometric files (IES files) for the LightLouver Daylighting System describe the amount and distribution of daylight they provide under various orientations, glazing and sky conditions. These IES files are valid for latitudes +/- 2.5o of the stated latitude and are provided for due east, south and west facade orientations. They are all created for a longitude aligned with a prime meridian (0, 15, 30, 45...) such that noon sees the solar disc with an azimuth angle close to 0deg from south. Other locations with longitudes further from a prime meridian will see the same amount of light and same solar paths but the exact azimuth angles of the sun at specific hours will vary to the right or left.