Shading Coefficents

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Author Message Michael Chusid Senior Member Username: michael_chusid Post Number: 19 Registered: 10-2003 Posted on Tuesday, April 21, 2015 - 03:34 pm:    I am specifying a perforated metal panel as a sun shading device. I need to control the maximum amount of direct sunlight that will hit a specific point under the device. In addition to the percent open area, this depends on the size of the openings, the height of the shade above the specific point, the orientation of the shade, latitude, the thickness of the metal, and other factors. Do you know how to calculate this? Do you know of standards that limit the amount of direct daylight to which medical patients can be exposed? Michael Chusid, RA FCSI CCS www.chusid.com www.buildingproduct.guru Greta Eckhardt Intermediate Member Username: gretaeckhardt Post Number: 4 Registered: 08-2013 Posted on Wednesday, April 22, 2015 - 10:32 am:    I am more familiar with the Solar Heat Gain Coefficient (SHGC) than the Shading Coefficient, but offer a couple of thoughts on estimating SHGC, which is basically the ratio of solar heat gain to incident solar radiation. SHGC is typically a function of low-e or other coatings on glass. IECC-2012/ASHRAE 90.1-2010 has provisions for adjusting the SHGC when shading is provided. First a Projection Factor is calculated using the ratio of dimensions for horizontal overhang and vertical height from sill to overhang. This ratio can be further modified by opacity of the overhang. Refer to IECC-2012, C402.3.3 and ASHRAE 90.1-2010 5.5.4.4.1. These are not detailed calculations and will only give an estimate, but at least the estimate is based on a well-defined protocol, and after all the presence of clouds, eclipses, and other factors means that solar heat gain cannot be a precise science. Lynn Javoroski FCSI CCS LEEDŽ AP SCIP Affiliate Senior Member Username: lynn_javoroski Post Number: 1997 Registered: 07-2002 Posted on Wednesday, April 22, 2015 - 12:13 pm:    I don't know if this book would be any help for the direct sunlight issue: "Guidelines for Design and Construction of Hospitals and Health Care Facilities" from AIA. They didn't have a Table of Contents on the website. I'd think, though, that the amount of direct sunlight would vary from patient type to patient type depending on medications and disease / illness. And although I cannot think of the name, there is software that would model the sunlight for a particular site, taking the latitude, orientation and time of year into account. Perhaps someone wiser than I will have the answers.