The cold hard truth > why Thermal Breaks in steel frames help reduce heat loss

Let’s talk about Thermal Breaks in steel frames, and how to do things properly to reduce heat loss.

In the world of modern building, steel is fairly important and indispensable as a structural material. It’s very strong, it allows for incredible spans and the open plan layouts many of us love. However, steel also has a ‘dark side’ that many projects ignore until it’s too late. Steel is a highway for heat.

If you’re a developer, homeowner, or fellow architectural technologist / architect, we need to have a serious talk about thermal bridges and thermal breaks.

What is a Thermal Bridge?

A Thermal Bridge [sometimes referred to as thermal bridging, a cold bridge or thermal bypass] describes a condition in a building where there is a direct connection between the inside and outside through one or more elements that are more thermally conductive than the rest of the building envelope.

Thermal Bridges are common in older buildings, which may be poorly constructed, poorly insulated, with single skin construction and single glazing.

In modern buildings, thermal bridging can occur because of poor design, or poor workmanship. This is common where elements of the building penetrate through its insulated fabric, for example around glazing, or where the structure penetrates the building envelope, such as at balconies or roof overhangs.

As a result, there will be wasteful heat transfer across this element, its internal surface temperature will be different from other, better insulated internal surfaces and there may be condensation where warm, moist internal air comes into contact with the, potentially cold, surface. This condensation can result in mould growth.

What is a Thermal Break?

Think of a Thermal Break as a “buffer” or a “speed bump” for heat. It slows down or even stops the heat transferring through these weak spots, or insulation layer penetrations.

A Thermal Break is often a layer of low-conductivity insulation material [like reinforced polyamide or specialised high-density foam] inserted between internal and external elements to stop that energy transfer in its tracks. Thermal breaks are often used in steel frames and also door and window frames.

I produced a little video where I show you a thermal break that’s been constructed on site and back this up with some architectural 3D model cutaway views to show how there is a hole in the thermal insulation.

Click to watch the video and learn more about how we fixed thermal bridging for this particular project.

As you can see on the video, there’s a bit of steelwork, and that’s going to suck out heat as it punctures the insulation zone.

So, how do we deal with that?

Well, we introduce what’s called a Thermal Break. If I zoom in, you can see one, right there.

On the 3D design model view you can see this a bit clearer, if I open up the wall and roof you can see the gap in the insulation. There you can see the steel beam poking through the insulation and creating a hole, that will suck heat out through it. As you can see, there is a clear gap between the wall and roof insulation. This is a thermally weak point, uh oh! Stripping the 3D model back further to the bare structural bones, the Thermal Break is shown as the orange pad, between post and beam.

Back on site, in the real world, between the steel post and the beam you can now see this physical Thermal Break. A pad of very strong, highly efficient insulation is bolted through. This insulation thermally separates the steelwork and reduces heat loss passing through the steel frame. As there is insulation up to this Thermal Break and around it, this insulation pad creates an almost continuous zone of insulation that is wrapped around the building.

That’s how you deal with it.

Are you using Thermal Breaks on steel frames on your projects? If not, is it worth considering? This took a bit of effort from me to ensure the team got their heads around it but I think it was worth it. Whew!

Hope this helps a bit if you are trying to make your building more energy efficient.