Written By: Brad Campbell | August 14, 2026
Windows are one of the biggest sources of energy loss in any building. Heat escapes through single-pane or outdated glass in the winter, and unwanted heat creeps in during the summer, forcing HVAC systems to work harder than they should.
Insulated glass panels for windows, commonly known as insulating glass units or IGUs, were developed to solve this exact problem, and today they're a standard feature in commercial and high-end residential construction and renovations.
An insulated glass panel is made up of two or more panes of glass separated by a spacer bar and sealed around the edges. The sealed cavity between the panes is filled with air or an inert gas, most commonly argon, which acts as a buffer against heat transfer. Instead of one solid sheet of glass conducting temperature straight through, the IGU forces heat to cross an insulating gap before it reaches the other side.
The basic components of an IGU include:
Because the unit is fully sealed, the airspace stays free of moisture and debris for the service life of the product, which is what keeps the insulating performance consistent over time.
Additional panes of glass improve insulation, but the insulating gap is what really does the heavy lifting. Heat naturally moves from warmer areas to cooler ones, and glass on its own is a poor barrier to that movement. By adding a gas-filled cavity between two panes, an IGU slows the rate of heat transfer significantly compared to single-pane glass. That means less heat loss in the winter, less heat gain in the summer, and a building that holds a stable interior temperature with less strain on mechanical systems.
That being said, glass selection also plays a role. Low-E coatings, tinted glass, and laminated interlayers can all be incorporated into an IGU to further tune its thermal and solar performance, depending on the climate and orientation of the building.
The spacer bar deserves its own mention here too. Older insulated glass window panels relied on aluminum spacers, which conduct heat efficiently and create a weak point at the edge of the glass where condensation and heat loss are more likely to occur. Most modern IGUs now use warm-edge spacer technology, made from materials with lower thermal conductivity, which reduces that edge-of-glass heat transfer and helps the unit perform more consistently across the entire pane, not just in the center.
Note that standard insulated glass panels for windows use two panes of glass, while triple-pane configurations add a third layer and a second sealed airspace for even greater insulating performance. Triple-pane units cost more and add weight to the assembly, so opting for triple-pane usually comes down to climate severity and how much of a performance gain the building actually needs to justify the added cost.
Energy efficiency is the main benefit of an IGU, but it's far from the only one. A high-performance insulated glass panel brings a combination of advantages that a single pane of glass or an outdated double-pane window simply cannot match.
That last point is especially important when it comes to implementing insulated glass panels in schools, government buildings, and other facilities where both energy efficiency and security are part of the project requirements.
| Feature | Single-Pane Glass | Standard IGU | Security-Rated IGU |
| Energy efficiency | Low | High | High |
| Noise reduction | Low | Moderate to high | Moderate to high |
| UV/glare control | Depends on coating | Depends on glass | Depends on glass |
| Forced-entry/impact protection | No | No | Yes |
| Typical use case | Non-critical openings | General commercial/residential | Schools, government, high-risk facilities |
The right IGU configuration depends on the building's climate, noise exposure, and any security requirements specific to the facility.
Schools, government buildings, places of worship, and commercial properties in higher-risk areas often need more than energy performance alone, which is why more manufacturers now offer IGUs that combine insulation with a security-rated panel on one side.
Riot Glass offers this exact combination through its AP-Series IGUs, pairing standard insulating performance with integrated security panels and a full line of interior glass options.
If you're evaluating insulated glass panels for an upcoming build or retrofit, contact Riot Glass to discuss which configuration makes sense for your building.
An insulated glass panel, or IGU, is made of two or more panes of glass separated by a sealed, gas-filled airspace that reduces heat transfer and improves comfort and energy efficiency.
Yes. The multiple glass surfaces and sealed airspace help dampen sound transmission compared to single-pane or outdated double-pane glass.
Yes. Security-rated panels can be integrated into the attack side of an IGU, combining forced-entry or impact protection with the energy efficiency and sound mitigation of a standard insulating unit.
Yes. Riot Glass's AP-Series IGUs combine the energy efficiency and sound mitigation of a standard insulating unit with integrated AP25, AP375, or AP375-BR security panels, plus a proprietary Shock Spacer™ that protects the seal from impact.
It depends on the manufacturer and framing system. Riot Glass AP-Series IGUs, for example, are designed to work with the Riot Glass Universal Framing System for single and dual-pane upgrades.
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