The Lighttex Sun Blocking Calculator
 A Direct Sun Blocking Percentage Comparison Between Blind/Louver Systems and Lighttex













Welcome to the Lighttex Sun Blocking Calculator! We have developed the Sun Blocking Calculator to provide our clients and prospective clients with an exclusive and advanced daylight control planning tool. The Sun Blocking Calculator is extremely easy to use. Simply specify the orientation of the skylight or window, and the geographic location of the project, and click for results. The results are presented in grids showing a percentage comparison of direct sun blocking between vertical blinds, horizontal louvers and Lighttex by the daylight hour and the season of the year. The increased percentage of direct sun blocking equates to improved uniformity of diffused interior reflected light.
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Size of Blind/Louver Size of Lighttex

Blocking of direct sunlight by Lighttex is determined from simple geometry (see the diagram below). When the Lighttex material directly faces the sun, there is no blocking. As the angle between the sun direction and the material increases, so does the amount of blocking.

The angle at which full (100%) blocking occurs depends on the cell depth and width.

Ten fixed window orientations and three different window coverings with comparative sizes including Lighttex panel are estimated in Eggcalc. The solar position JavaScript routines used in Eggcalc come from Solar Position Calculator, by Surface Radiation Research Branch, National Oceanic & Atmospheric Administration, US Department of Commerce. These routines are based on equations from Astronomical Algorithms, by Jean Meeus. The sunrise and sunset results have been verified to be accurate to within a minute for locations between +/- 72° latitude, and within 10 minutes outside of those latitudes. Simple mathematical geometry is applied to calculate the ratio of direct sun blocked shadow area over the whole area by which direct sun goes through.

Note that computer simulation results can be different from actual due in part to:

  1. The effects of atmospheric refraction especially when latitudes are greater than 72° north(North to Alaska, US) or less than 72° south (Antarctica);
  2. A small solar position difference as year 2004 is used as a typical year in Eggcalc. The sun drifts slightly in its orbit over time. We think the amount is small enough to be ignored.

Lighttex Canada Inc. assumes no responsibility for the use or suitability of this software. The software is provided "as is" without warranty of any kind, either express or implied, including, but not limited to the implied warranties of the merchantability and fitness for a particular purpose. The entire risk as to the quality and performance of the software is with the user. Lighttex Canada Inc. does not warrant that the functions contained in this software will meet user requirements, or that the operation of the program will be ininterrupted or error free.

© 2005 Lighttex Canada, Inc.







For your interest, we also provide data which compares the direct sun blocking performance of Lighttex dependant on cell size. The standard depth of Lighttex is 3”. By decreasing the width and height of the egg crate cells, additional direct sun blocking is possible.

The need for Lighttex is dramatically illustrated in those cases where the orientation of the window, the time of day, and certain seasons of the year would make the glare and heat gain from an open vertical or horizontal window covering intolerable. Lighttex outperforms in all cases.

You may access our foundational research and data for the calculator by visiting our Lighttex Daylighting Study.