Processed Glass

This page provides additional descriptions on the different types of processed glass included in the EC3 database so that users can ensure they find EPDs that are appropriate for their needs.

Processed glass types can vary significantly in terms of GWP, so it is critical that users understand the types of processed glass. Please note that in product category rules (PCRs) such as the UL Part B PCR for Processed Glass, the term processed glass can be used to refer to both monolithic glass panes or an insulating glass unit (IGU). However, due to concerns about comparability, the EC3 tool has separate categories to distinguish between flat (unprocessed) glass, monolithic processed glass, and IGU. The descriptions below are the processing types which can be searched under both the (monolithic) processed glass and IGU categories. The descriptions are for the most common types of processed glass used in construction and that are listed in NGA’s GANA Glazing Manual.


Low-e is glass that has been coated with thin layers of metallic oxides to allow visible light to pass through the glass while limiting the amount of energy. There are two different types of low-e coatings. Passive low-e coatings, which are designed to maximize the solar heat gain and limit the reliance on artificial heating and solar control low-e coatings which are designed to limit the amount of solar heat and reduce the amount of cooling.


Electrochromic glazing serves as an absorptive and dynamic solar control coating, capable of reversible changes in tint/transparency affecting optical properties like light transmission, infrared transmission, and solar heat gain coefficient. Electrochromic glazing can change its tint in response to an applied voltage based on external readings like the sun position and radiation intensity, offering dynamic control over light (daylight, glare) and heat entering a space. The ability to modulate its optical properties allows building envelopes to adapt to environmental conditions enhancing building energy efficiency and comfort.


Acid-etched glass is decorative architectural glass, which is used for its aesthetic qualities. Processing may include mechanical or chemical procedures which change the visual properties of the glass.

Heat-treating, Tempering, and Toughening

Heat-treated glass is a term used to describe glass that has been processed through an oven to change its strength characteristics and provide greater resistance to both thermal and mechanical stresses. There are two processes for heat-treating glass. Heat-strengthened glass, which is approximately twice as strong as annealed glass and breaks into fragments that are similar in size and shape to annealed glass. Tempered glass which is generally considered four times stronger than annealed glass and shatters into many small pieces. Currently, EC3 does not distinguish between different types of heat-treated glass because large differences in GWP are not expected to exist.


Laminated glass is used for improved security and safety performance properties. Additionally, it is often associated with additional desirable properties such as sound reduction and solar and thermal control. Laminated glass is commonly used in specialty applications for aquariums, animal enclosures, glass stairs, and sports stadiums.


Fire-rated glass can either be fire-resistant or fire-protective. Fire-resistant glass restricts the spread of flames, smoke, and radiant heat for 60 to 120 minutes. It uses intumescent multi-laminate and gel-filled units to reach this rating. Fire-protective glass, on the other hand, is tested for its ability to block flames and smoke, but not radiant heat. These products range from covering specialty tempered products rated for around 20 minutes of protection to glass ceramics rated to 3 hours or more.

Pyrolytic Coated & Sputter Coated

Surface coatings may be applied to glass to modify appearance or provide additional characteristics or functions such as altered reflection, transmission, or absorption properties, scratch resistance, or corrosion resistance. Coated glass may be produced by either vacuum deposition (i.e., sputter-coated) or pyrolytic deposition. Vacuum deposition involves applying coatings to glass products in a vacuum chamber; pyrolytic deposition applies coatings during the flat glass manufacturing process. Low-e or aesthetic coatings can be applied by either of these processes.

Please note: pyrolytic coating and sputter coating are methods by which a variety of different coatings can be applied, and thus searching for EPDs tagged as Pyrolytic Coated or Sputter Coated, will not yield a certain performance type, but rather that the resultant EPDs were produced via one of these methods.

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