Calculating the Theoretical Life Expectancy of an Insulating Glass Unit

Werner Lichtenberger, TruSeal Technologies Inc.

There are many variables that contribute to the life expectancy of a typical insulating glass unit. These variables can be divided into three broad categories; variables in the design or material composition of the insulating glass edge seal and spacer, variables in the process of assembling the insulating glass unit including workmanship and the installation into the glazing system and finally the service conditions of the IGU in its intended application. In this paper we examine the theoretical or design and composition elements of insulating glass durability.

The basic elements that contribute to the length of service life of a unit include the moisture resistance of the materials used to effect the seal between any moisture barrier and the edge of glass, the amount of desiccant used and its moisture absorption capacity in relation to the volume and humidity in the IGU, the length of the moisture vapor transmission path through each material in the IG seal design and the width of this path between the moisture barrier and the edge of the glass. Based on these variables a theoretical desiccant depletion model can be created and a probable life expectancy can be calculated. We will also examine the impact of changing materials or design and how this affects life expectancy.

In conclusion some probable causes of premature insulating glass failure are posed and compared to the theoretical life expectancy.

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The Authors

Mr. Werner Lichtenberger Special Projects Manager TruSeal Technologies Inc Werner Lichtenberger is the Special Projects Manager for TruSeal Technologies Inc. of Cleveland, OH. TruSeal is an international manufacturer of insulating glass systems and glazing sealants. Mr. ... Read more