What is Thermal Bridging?

In the construction industry, there is a phenomenon known as thermal bridging. Thermal bridges are critical in building design and construction, yet they are often overlooked. If you’re a newcomer to the cold room industry, you might hear the term “thermal bridge” from technicians during the construction of a cold room. So, what exactly is a thermal bridge?

In this article, I will provide a comprehensive introduction to thermal bridges, including their concept, types, impacts, measurement methods, and how to reduce thermal bridging effects. This will help you gain a deeper understanding of thermal bridging and its significance in construction.

Construction Industry

Concept of Thermal Bridging

Thermal bridging, as the name suggests, acts as a bridge for heat. It occurs when a specific area of a building has better thermal conductivity than the surrounding areas, creating a pathway for heat transfer. Heat from the warmer side can easily flow through this “bridge” to the cooler side.

Concept of Thermal Bridging

In essence, a thermal bridge provides a path of least resistance for heat transfer. It describes the phenomenon where heat conducts more quickly through a particular area of a building due to its superior thermal conductivity compared to adjacent areas.

 

Impact of Thermal Bridging

When a building has thermal bridges, heat can easily flow in or out through these areas, making the building’s internal temperature more susceptible to external temperature fluctuations. During summer, heat can enter the building more readily through thermal bridges, increasing cooling demands. Conversely, in winter, heat can escape through these bridges, increasing heating requirements. This leads to higher energy consumption and, consequently, higher electricity bills.

Additionally, the surface temperature at thermal bridges tends to be lower. When warm air encounters these cooler surfaces and reaches the dew point, condensation occurs. This condensation can lead to moisture accumulation, increasing the material’s absorbency and reducing its insulation performance. Damp materials can also promote mold growth, which not only affects the building’s aesthetics but also poses health risks.

Therefore, addressing thermal bridging in building design and construction is crucial. Implementing effective measures to minimize thermal bridges can significantly reduce their negative impact on energy efficiency, structural integrity, and indoor air quality.

 

Types of Thermal Bridges

Thermal bridges occur in areas with better thermal conductivity and lower thermal resistance. They can be found in various parts of a building and are generally categorized into the following types:

Geometric Thermal Bridges

Geometric Thermal Bridges

Geometric thermal bridges arise from the structural shape of a building. They occur at intersections of two or three planes, such as corners, balconies, and the junctions of roofs and walls.

Material Thermal Bridges

Material thermal bridges result from differences in thermal conductivity between materials used in construction. For example, components like steel reinforcements and other metal parts have high thermal conductivity and thus create thermal bridges.

Repeating Thermal Bridges

Repeating thermal bridges occur due to the regular spacing of building components like steel reinforcements or insulation materials within the building’s envelope. For instance, regularly spaced steel reinforcements in a wall can create repeating thermal bridges. Similarly, discontinuous insulation materials can lead to repeating thermal bridges.

Linear or Non-repeating Thermal Bridges

Linear thermal bridges form at joints between materials with different thermal conductivities, such as the seams between doors or windows and walls. They can also occur when there are gaps in the building envelope, such as breaks in insulation layers or poorly sealed joints between insulation panels.

Point Thermal Bridges

Point Thermal Bridges

Point thermal bridges are created when specific areas or points in a building have materials with higher thermal conductivity than the surrounding materials. Examples include fasteners, bolts, screws, and metal brackets, which often form point thermal bridges.

 

Methods for Measuring Thermal Bridges

As previously discussed, a thermal bridge occurs when an area of a building has better thermal conductivity than the surrounding regions. This results in heat from the warmer side transferring more easily to the cooler side through the thermal bridge. Consequently, the temperature distribution in the area of the thermal bridge will differ from that of the surrounding areas. Leveraging this characteristic, infrared thermography is widely used to measure the location of thermal bridges in buildings.

Infrared Thermography

All objects emit infrared energy, and the intensity of this radiation depends on the object’s temperature. Higher temperatures result in greater infrared radiation intensity. Infrared thermography detects the differences in infrared radiation intensity across different areas of a building’s surface and converts these differences into visual images. This method vividly displays the temperature distribution across the building’s surface, allowing the identification of thermal bridges through areas with abnormal temperature distributions.

Infrared thermography

Infrared thermography is simple to operate, highly adaptable, and can be widely used in various buildings and structures. It provides a quick and intuitive way to identify the location of thermal bridges. However, it can only qualitatively measure the presence and location of thermal bridges and cannot quantify the heat loss caused by thermal bridges. Additionally, the accuracy of infrared thermography can be affected by environmental conditions and the subjective judgment of the operator. Factors such as small temperature differences between the interior and exterior of the building, shaded areas, wind speed, and humidity can all impact the imaging results, leading to potential inaccuracies in identifying thermal bridges.

To obtain a quantitative analysis of heat loss through thermal bridges, infrared thermography can be combined with tools such as heat flux meters and thermocouple sensors. This approach allows for a more precise measurement of the thermal energy lost due to thermal bridges.

 

How to Break Thermal Bridges

Use Thermal Breaks

Thermal breaks refer to materials with low thermal conductivity, which are poor conductors of heat. Examples include insulation materials such as extruded polystyrene foam, polyurethane foam, and expanded polystyrene foam.

Ensure Continuity of Insulation

As mentioned earlier, interruptions in the insulation layer can create linear thermal bridges. Therefore, it is essential to ensure the continuity of the insulation during installation. Insulation panels should fit tightly together without gaps or breaks.

Proper Sealing

Proper Sealing

Joints in various parts of a building, especially between doors, windows, and walls, often form thermal bridges. To reduce heat loss or gain at these joints, it is important to seal gaps between doors, windows, and walls. If necessary, use continuous insulation materials to cover the joints between different parts of the building, such as between doors and walls, walls and floors, and wall-to-wall connections.

 

Conclusion

In summary, the issue of thermal bridges in buildings should not be overlooked. Thermal bridges can lead to increased energy consumption, reduced building lifespan, and decreased comfort for occupants. This article has explained what thermal bridges are and provided some solutions to minimize their formation. We hope this information is helpful to you.

 

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