igma general“Use of Fourth-Surface Coatings in a Cold Climate,” presented by Tim Clancy and Lisa Green of Guardian Industries, was one of the main topics of discussion today at the 2013 Insulating Glass Manufacturers Alliance Annual Conference in New Orleans.

The presentation, which was based on a study Guardian conducted, noted that the main goal of the study was the investigation of “real-world implications of the National Fenestration Rating Council (NFRC) 500 condensation resistance (CR) number as it pertains to the use of fourth-surface low-E coatings in cold environments in conjunction with a low-E on the third surface of a dual-glazed insulating glass unit (IGU).”

For the study, which took place between Fall 2011 and Fall 2012, six double-hung windows with vinyl frames were examined. The windows had a 16-mm gap with 90-percent argon, 10-percent air fill.

Additionally, interior temperature was maintained at 70 degrees Fahrenheit with three different relative humidity (RH) levels of 30 percent, 40 percent and 50 percent. Outdoor conditions included a 12.3-mile-per-hour wind, temperatures varying between 65 to -20 degrees Fahrenheit, held steady between 0 and -20 degrees Fahrenheit at night.

The presentation included videos of the condensation tests performed to show the differences in condensation between the traditional low-E window and the traditional low-E with surface 4 coating. Results of the 30-percent tests showed relative consistency in the levels of condensations, similar to the results seen for the 40-percent condensation tests. The 50-percent test showed that the fourth surface coated window had condensation which appeared much more quickly and grew at a faster rate than the lower humidity tests.

“The condensation front only differed for about a ½ inch to an inch with the addition of the surface four; when you get to higher humidity you see the fully condensed surface,” said Green. “The basis of this study was to determine if CR was a good method for determining condensation; we found it was a fairly good predictor.”

The IGMA conference continues through Friday. Stay tuned to www.usgnn.com™ for the latest from the event.