How Does Fire-Resistant Glass Protect Against Radiant Heat?

Fire-resistant glass commonly achieves radiant heat protection through the incorporation of transparent intumescent interlayers. When these assemblies are exposed to high heat, the intumescent interlayers swell into an opaque insulating rigid foam char.

As an example of radiant heat-blocking glazing, Pilkington Pyrostop® uses intumescent interlayers between Pilkington Optiwhite™ wireless, low-iron float glass to prevent the spread of smoke and fire while reducing heat transfer for up to 120 minutes. This fire-resistant glass can pass the hose stream test and is impact safety-rated according to ANSI Z97.1 and CPSC 16 CFR1201 (Cat. I and II) standards.

When specifying this material, knowing what radiant heat is and when radiant heat protection is required can help project teams make code-compliant choices for their designs.

What is radiant heat in a fire?

Radiation is one of three methods heat uses to travel (the other two being conduction and convection). Radiant heat is caused by electromagnetic waves that are absorbed when they strike an object. In a building fire, it can cause unbearable pain in occupants and spontaneous combustion of materials, both of which can make means of egress paths unusable.

When is radiant heat protection required by code?

According to Chapter 7 of the 2024 edition of the International Building Code (IBC), most fire walls, fire barriers and fire partitions as well as some opening protectives within these elements of the built environment will require radiant heat protection. This is because blocking radiant heat helps maintain the integrity of structural elements, delay instances of spontaneous combustion of objects on the non-fire side of the barrier and safeguard egress for human evacuation.

In addition to opaque materials, fire-resistant glass offers code-compliant radiant heat protection without limiting daylight access or visual connection. Further, because radiant heat-blocking glazing is treated as a fire barrier, it can support compartmentation strategies. This type of glazing can also influence the rating requirements of openings within these fire-rated glass wall assemblies.

Technical Glass Products offers a large library of case studies to demonstrate how teams have used fire-resistant glass to maintain both transparency and radiant heat protection in several applications. Read through them to discover the design potential of radiant heat-blocking glazing.