What are insulated glass units and what are their applications?

Insulated glass units, also known as thermo-insulating glass, are commonly used in windows. They consist of two or more glass panes separated by a space filled with gas. The basic components of an insulated glass unit are the glass panes, the inter-pane space, the spacer bar, seals, and desiccants.

Glass panes are single or laminated glass sheets that form the outer layers of the insulated glass unit. Their thickness depends on the requirements for thermal and acoustic insulation. The inter-pane space, which separates these panes, is filled with gas (most commonly argon) or a vacuum, improving thermal insulation.

The spacer bar is a metal or plastic profile that maintains the proper distance between the glass panes, adds rigidity and stability to the structure, and can enhance thermal insulation if made from materials with low thermal conductivity (known as warm-edge spacers). These spacers often contain desiccants, typically silica gel, which prevent condensation inside the glass unit by absorbing moisture.

Seals, usually made of butyl, prevent air, moisture, and contaminants from entering the inter-pane space, providing flexibility and durability to the connections between the glass panes.

Insulated glass units can be tailored to different needs, such as thermal and acoustic insulation, protection from solar radiation, privacy (with frosted or patterned glass), and safety. Butyl, used as a sealant, is highly resistant to atmospheric factors, UV radiation, and temperature.

Thermal bridges, areas with higher heat conduction, can reduce the thermal insulation of the insulated glass unit, especially where the spacer bar contacts the glass panes. To minimize their impact, manufacturers often use spacers made from materials with low thermal conductivity.

Condensation can occur on the surface of the spacer if it is cooler than the surrounding air. To avoid this, proper ventilation of the rooms, maintaining appropriate relative humidity, and good thermal insulation of the entire window structure are recommended. The dew point, the temperature at which water vapor in the air condenses, depends on the relative humidity of the air; the higher the humidity, the higher the dew point.

Ensuring proper design and selection of insulated glass units with minimal risk of condensation, along with the use of appropriate insulating materials and ventilation, is crucial for the durability and efficiency of thermo-insulating windows.

Description of the upper image:

1.  glass pane 2. inter-pane space 3. spacer bar 4. butyl seal 5. molecular sieve (desiccant) 6. sealant