Thermal Bridge Free Construction

Thermal bridges, also known as cold bridges, are areas in a building envelope that have a higher heat transfer rate compared to the surrounding areas. They typically occur at points where different building components are joined, such as window and door frames, wall-roof junctions, and other building penetrations. Thermal bridges compromise the building's energy efficiency, resulting in increased heating and cooling costs, and reduced indoor comfort levels.

Following on with our puffer jacket analogy from the insulation article. Let’s say it’s a cold winters day in Wellington and the southerly is blowing. But are you wearing your puffer jacket you are nice and warm; except you forgot your gloves. Now your hands become a thermal bridge and you can feel the cold moving up your arm. The solution is to put your hands into the pockets of your puffer jacket. They now start to warm up as you have a layer of duck-down between your bare hands and the cold wind, thereby reducing the thermal bridge.

This is exactly what are try to do at all the connections in your Passive Home. We carefully detail the junctions between constructions to minimise thermal bridging, so that there is no direct path from the cold exterior to the warm interior. When we have a complex connection between different constructions, we install insulation between the timber / steel / concrete and the exterior, just like putting your hands in your pockets. When working on a certifiable Passive House we will then model the actual construction in a thermal modelling software package to confirm the heat loss factor (Psi value) of the junction and ensure there is no risk of mould growth.

An easy way to minimise thermal bridging is by carefully considering the construction methods for your home. Smart choices could be using insulated concrete forms (ICFs), structural insulated panels (SIPs), or exterior insulation on the walls, and a warm roof. This was briefly covered in our insulation article (click this link to read the insulation article).

Proper air sealing is also crucial in a Passive House to reduce thermal bridges. This includes the use of high-performance windows and doors, air and vapor barriers, and proper seals at joints between building components.

It's essential to note that even small thermal bridges can have a significant impact on the energy efficiency and indoor comfort of a Passive House. That's why it's crucial to engage a Certified Passive House Designer and builders to ensure that thermal bridges are eliminated, and the building performs as designed.