Inboard monolith5/11/2023 ![]() The additional airspace allows for better insulating properties, improving the unit’s u-vale. A unit with three lites of glass and two sealed air spacers will have three times the insulating value. Since the heat flow resistance of still air is much greater than that of glass, a glass unit made of two panes enclosing an air space will have about twice the insulation value of a single pane window (half the heat loss). How IGUs WorkĬlear monolithic glass accounts for less than 5% of a window’s insulation value, the rest is being supplied by the still air layers of the environment on either side of the glass. ![]() When combined with a low-e or reflective coating, the insulating performance of IGUs is significantly improved. The hermetically sealed air space creates a barrier for heat and sound transfer making IGUs very effective in reducing air-to-air heat gain or loss. Insulating Glass Units are sometimes called Double Glazing or Sealed Insulating Glass Units (SIGU).Īn insulated glass unit (commonly referred to as an IGU or IG) is comprised of 2 or more lites of glass, separated with a desiccant filled spacer bar and is hermitically sealed around the edges to form a single unit. They are used to reduce building heat loss and/or heat gain depending on the climate and glass configuration. In the submittal process, we encourage contractors to protect themselves by informing all parties of the potential color volatility, and expanding the viewing to include larger samples in exterior conditions.Ĭlick here to view the SCGMA Technical Bulletin as a PDF.Insulating Glass Units (IGUs) are designed to provide thermal insulation for building envelopes. Glass samples are typically submitted for architectural approval, but since the color shift is subtle, many times it is difficult to detect. Color shift when using embedded Low-E coatings in laminated glass is not considered a product defect, but has caused architectural rejection of installed products. Therefore, IG units with Low E coatings embedded inside the laminate may not match units with the same Low-E exposed to the IG airspace. The extent of any color shift is dependent on several factors including the choice of coating used and whether that coating is on surface #2 or surface #3 of the laminate. Low-E coatings are designed for use in IG units with argon or air next to the coating, so placing them in contact with the laminate’s interlayer may cause a shift in color. Again, performance will vary based upon the coating placement.Įmbedding the Low-E coating next to the interlayer has the potential to affect the optical properties of the laminated glass. Alternatively, coatings can be embedded on an outboard laminate between the glass layers on the #2 or #3 surface, followed by an airspace and inboard monolithic glass. When using a Low E laminated insulated glass unit, it is most common to have the coatings applied to the #2 surface, followed by an airspace and an inboard laminated. Performance will vary based upon the coating placement. Placing the Low-E coating inside the laminate will help prevent damage while maintaining the solar heat gain coefficient of the coating. When using a monolithic Low E laminated glass make up, it would be likely that the coating would be embedded between glass layers on the #2 or #3 surface. There are several influences that determine a laminated glass makeup, including the placement of Low E coatings in the overall unit. Rejection of installed laminated Low E glazing due to subtle color shifts has been an issue and is the subject of this technical bulletin. Occasionally, risk elements present themselves in the commercial glazing business, and we believe that it is helpful to address them.
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