Understanding Thermal Bridging to Decrease Winter Energy Bills

By Kaia Koglin

November 27, 2024

It can be hard to stay warm in the depths of winter, especially if there seems to be a cold spot in your house. You may suspect a poorly sealed window or the wind getting under a door. But there may be a tunnel in your house letting heat quickly escape.

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The phenomenon is known as thermal bridging, and these sneaky spots can increase your energy bills as you try to replace the warm air that's fleeing. Understanding how thermal bridging works and how to prevent it can help you stay warm and save money.

What Is Thermal Bridging, and What Does It Have to Do With My Home?

You'll sometimes see thermal bridging referred to as cold bridges, heat bridges or thermal bypasses. To define thermal bridging, you first have to delve into science. Heat spontaneously travels from hot objects to cold objects, a process known as thermal conduction. Different materials conduct heat at different rates, and the heat will look for the path of least resistance.

A thermal bridge is created when part of an object, such as a building, conducts more heat than other parts of the object. The higher conductivity makes heat travel along that path unless there's something to stop it.

For example, steel is a good conductor of heat. In a steel-framed house with insulation, the frame can become a thermal bridge, taking heat from inside your house to the outside. This is because it's more conductive than the surrounding insulation.

As thermal bridges make heat leave during winter and enter during summer, they can make your house less comfortable. They also lead to more energy use — and higher bills — as your HVAC works harder to combat the heat transfer.

Does Thermal Bridging Cause Mold?

On top of the higher energy bills, thermal bridging can also bring mold. When warm air comes into contact with a colder surface, condensation occurs. This moisture can cause mold, leading to lower air quality and potential health impacts.

Where Is the Most Common Place for Thermal Bridging to Occur?

Thermal bridging commonly occurs in places where highly conductive materials are used. This can include the house frame and window frames. Any place the building is penetrated can also become a thermal bridge, such as where pipes and cables enter your home. Brackets and connection points for things like balconies can also become thermal bridges.

Any interruption of insulation in the house is another common place where heat can enter or exit the building. Junctions between the floor, wall and roof often have breaks in insulation, causing thermal bridges. This is why cold spots often occur in the corners of rooms.

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What Are Some Ways to Prevent Thermal Bridging?

Thermal bridging is usually a problem with the design of a building, and preventing thermal bridging also has to happen in the design stage. Things to discuss with an architect or builder include:

Changing building materials for ones that are less conductive
Moving or removing the material that's causing the thermal bridge
Removing air gaps
Creating a thermal break by interrupting airflow with a low conductivity element

If it's too late to fix the design of your house, insulation can be used to disrupt existing thermal bridges. It's important to install the insulation correctly. Make sure the insulation doesn't have any gaps, as any missing insulation can create a new thermal bridge. You can insulate existing thermal bridges, such as pipes, to stop the heat escaping. Lastly, if you're installing any bulk insulation, such as batts and rolls, make sure it doesn't get compressed. Compressed insulation is a better conductor of heat than insulation that's properly installed.

How Do You Reduce Thermal Bridging Around Windows?

Windows can be a common spot for thermal bridges, especially in older homes. In the past, window frames weren't designed with insulation in mind. Aluminum frames quickly let heat escape, as does glass. Thankfully, these can be fixed.

First, consider double- or even triple-glazing to keep cold air out and warm air in. Thermal breaks can also be added to glass using gas-filled glazing. New frames of a low-conductive material, such as wood, fiberglass or PVC, can be very beneficial to your comfort and energy bills, especially when insulating air chambers are included in the design. Finally, never underestimate the power of proper installation. Even the best-designed and insulated window frames will let warm air out if the space isn't properly sealed.

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