Thermally Broken Steel Windows & Doors

Durable and Energy-Efficient Thermally Broken Steel Windows and Doors

Our custom steel and glass doors and windows can be ordered as thermally broken units to minimize energy loss in demanding climate applications such as high altitudes, all-day sun exposure, or refrigerated applications. Thanks to advances in fabrication and glazing technology, it’s now possible to combine the slimmest of sight lines with high energy efficiency: our thermally broken French steel windows and doors.

Thermally broken steel door and window technology creates a barrier between the interior and exterior sides of the window or door frame and other components. Installing steel windows with thermally broken frames helps prevent heat or cold from moving through the steel. Thus, a “thermal break” creates a “barrier” to help keep interior surfaces at their ambient temperature. Among other approaches, The French Steel Company employs Polar Shield™ technology for its thermally broken designs.

With a U Factor as low as 0.41, Polar Shield™ doors are the only steel frame windows and doors suitable for all parts of the USA & Canada.

View our thermally broken products in greater detail using our drawing index.

Energy-Efficient Thermally Broken Steel Doors & Windows From Coast to Coast

R Values and U Factors are metrics for evaluating energy efficiency. The difference is that R-value is a measurement of heat loss through a single material, like a sheet of glass, a panel of wood, or a unit of fiberglass insulation. U Factor is the measurement of heat loss through a complex assembly, like a door or window unit.

U Factor is calculated using the R Values of all the insulating layers of the various regions of a complex structure – it is the reciprocal of the average R-value for the whole unit. The lower the U Factor, the lower the heat loss through the unit.

The U Factor of a Polar Shield™ thermally broken door is 0.41 compared to 4.0 for a non-thermally broken door. Polar Shield™ thus offers 10 times more insulating protection than a typical steel door.

Summary: Thermally-broken windows and doors are engineered and fabricated to provide the highest level of energy efficiency. As such, they are more costly to manufacture. Ask your French Steel Company representative to review the energy options and requirements for your installation.

Glass for Steel Windows and Doors

We offer a wide range of glass options to further customize your steel doors and windows. For doors, glass choices are based on whether the doors are intended for an exterior entryway or an interior, how much privacy and light are desired, and the overall energy requirements and architectural design.

Door glass panels are typically insulated and tempered for safety. Many special-order patterns are available, as well as laminated impact-resistant glass for coastal hurricane zones. All of our glass offerings feature clear and multiple levels of Low-E for UV filtration and protection.

Contact Us for All Your Thermally Broken Steel Window and Door Needs!

The French Steel Company knows how annoying it can be to sacrifice beautiful doors and windows to try to keep your energy bills low. That’s the reason we make sure our thermally broken steel windows and doors are beautiful and energy bill friendly. We would never want to have to sacrifice anything for our own homes and business – and neither should you!

Contact us today to find the best thermally broken steel doors and windows for your business or home from Florida to California.


  • Available in carbon steel
  • True thermally broken frames and operating panels
  • Eliminates interior condensation and frost
  • Resists even the highest summer temperatures
  • Accommodates double and triple glazing
  • Factory-installed multiple thicknesses, tempered and insulated glass
  • Electric arc hot zinc spray process for corrosion prevention

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Steel Doors

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Thermally Broken

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