Thermal bridge

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Temperature distribution in a thermal bridge

A thermal bridge is created when materials that are poor insulators come in contact, allowing heat to flow through the path created. Insulation around a bridge is of little help in preventing heat loss or gain due to thermal bridging; the bridging has to be eliminated, rebuilt with a reduced cross-section or with materials that have better insulating properties, or with an additional insulating component (a thermal break).

Thermal or heat bridges in building constructions are often called by the less scientific name "cold bridge".

Thermal bridges are characterized by multi-dimensional heat flow, and therefore by the fact that they cannot be adequately approximated by the one-dimensional models of calculation typically used in norms and standards for the thermal performance of buildings (U-values). Surface moisture due to condensation (typically occurring in such regions as floor-wall connections, window installations, etc.) as well as mold growth in humid environments can also be effectively prevented by means of multi-dimensional evaluation during planning and detail design.

Concrete balconies that extend the floor slab through the building envelope are a common example of thermal bridging.

Classification in construction

In construction, thermal bridges are classified as:

• Repeating thermal bridges - where bridges occur following a regular pattern, such that made by wall ties penetrating a cavity wall.
• Non-repeating thermal bridges - such as the bridging of a cavity wall by a single lintel
• Geometrical thermal bridges - at the junction of two planes, such as at the corner of a wall.

See also

• Thermal conductivity

External links

• EU Information Portal BUILD UP - energy solutions for better buildings: Community 'Thermal bridge forum'
• EU IEE SAVE Project ASIEPI: topic 'Thermal bridges' - An effective handling of thermal bridges in the EPBD context
• Passivhaus Institute: Thermal Bridges in construction - how to avoid them
• Analysis of Thermal behavior of Building Constructions with Thermal Heat Bridges
• A bridge too far - ASHRAE Journal article on thermal bridging
• Basics and Some Theory of AnTherm
• Theoretical background

References

de:Wärmebrücke