The terms thermal Thermal Bridge and a Thermal Break are often mistaken for one another, they actually have opposite meanings.
Thermal Bridge
A thermal bridge is a part of the construction that has a higher thermal conductivity than the materials around it. It is essentially a path of least resistance that heat can use to enter or leave the building envelope, thus decreasing the thermal resistance of the whole construction.
There are three ways heat can transfer through the building elements, conduction, convection and radiation. In the case of thermal bridging, heat is moving by conduction and the rate at which it moves is determined by temperature difference at each end of the thermal bridge as well as the thermal conductivity of the material that makes up that bridge.
Since the heat is entering or escaping the building, it is clear that the effect of thermal bridging is a decreased thermal resistance of the building, which leads to increased energy costs and decreased occupant comfort.
A thermal bridge, also called a cold bridge or heat bridge, is an area or component of the fabric which has higher thermal conductivity than the surrounding materials, creating a path of least resistance for heat transfer. Thermal bridges can significantly reduce the thermal performance of a facade, increasing energy use from a building’s heating and cooling systems. If not accounted for, they can also cause unwanted condensation and comfort issues in a building. - National Construction Code.
Thermal Break
A way to mitigate thermal bridging is to add a material with lower thermal conductivity, like insulation, between the building elements to prevent the flow of heat. This is what is known a as a thermal break. An efficient thermal break that prevents thermal bridging is a continuous layer of insulation.
Continuous insulation, as the name suggests, is not interrupted by materials that have high thermal conductivity. Rigid board insulation, which does not need a framed system for support, is an example of continuous insulation. Continuous insulation slows the heat movement through the building elements, improves the performance of the building envelope, and helps you achieve better energy efficiency and provide better occupant comfort levels.
With the introduction of a direct reference to NZS 4214: 2006 in the new National Construction Code, thermal bridging will need to be taken into account in thermal computations for most building classifications, from May 1st 2020. Knowing the difference between thermal bridges and thermal breaks, as well as how you can improve your building envelope by using continuous insulation has never been more relevant.
To further understand the difference between thermal bridge and a thermal break and to learn how to mitigate thermal bridging, book our free webinar which dives deep into the updates of NCC 2019.
Kingspan Insulation enlisted Norman Disney & Young to conduct a thermal performance comparison assessment between a traditional wall lining system with bulk insulation against the continuous insulation wall lining system.
Click below to read more on the white paper – Thermal Bridging: How to Manage it Using Continuous Insulation
