Thermal breaks, IGUs and safety glass: where each belongs

Thermally broken aluminum profiles

Aluminum conducts heat readily. A thermally broken profile separates the interior and exterior portions of the frame with a low-conductivity polyamide or similar structural barrier. This interrupts the direct heat path through the metal.

Thermal breaks improve energy performance and help keep interior aluminum surfaces warmer in winter, reducing condensation risk when the full wall assembly is properly designed. They are commonly used in exterior curtain wall, window wall, doors and higher-performance storefront systems.

Insulating glass units (IGUs)

An IGU combines two or more glass panes around a sealed spacer cavity filled with dry air or an insulating gas. The sealed space slows heat transfer much more effectively than a single pane.

IGUs are used in exterior windows, curtain walls, storefronts and glazed doors wherever the envelope needs thermal performance. Glass thickness, spacer type, cavity width, gas fill and edge seal are selected as part of the specified system.

Low-E coated glass

Low-emissivity, or Low-E, glass has a very thin coating that limits radiant heat transfer while allowing visible light through. Depending on the coating and the surface where it is placed inside an IGU, it can reduce winter heat loss, manage solar heat gain or balance both.

Low-E glass is typically used as a component of an exterior IGU in façades, windows and doors. The selected coating should match the project energy model, orientation, appearance target and risk of thermal stress.

Tempered safety glass

Tempered glass is heat treated to increase its strength and to make it break into relatively small particles instead of large sharp shards. Once tempered, it cannot be cut or drilled, so all fabrication must be completed first.

It is commonly specified at doors, shower enclosures, sidelites, low glazing and other hazardous locations identified by the applicable building code. It is also used where the glass needs added resistance to thermal or mechanical stress.

Laminated safety glass

Laminated glass bonds two or more plies to a plastic interlayer. If the glass breaks, the interlayer helps retain the fragments and keeps the opening covered. Different interlayers can add security, acoustic or structural performance.

Typical uses include overhead glazing, canopies, skylights, security glazing, sound-control assemblies and locations where post-breakage retention matters. The exact make-up must follow the drawings, engineering and code requirements.

These properties can be combined

The terms describe different parts or treatments, not competing products. An exterior IGU can include Low-E coating, tempered panes, laminated panes—or a combination—inside a thermally broken frame.

Final selection depends on energy, structural, safety, acoustic, security and appearance requirements. Confirm the glass schedule and system details before release so procurement and fabrication match the design intent.

Where the project documents reference U.S. requirements, products and fabrication should be supported by the applicable ASTM standards and, for safety glazing, criteria such as ANSI Z97.1 or CPSC 16 CFR 1201. Compliance is confirmed through approved submittals, manufacturer documentation and the authority having jurisdiction.