Thermal Bridging in Building

April 30, 2020

Thermal bridging is the movement of heat across an object that is more conductive than the materials around it. The conductive material creates a path of least resistance for heat. Thermal bridging can be a major source of energy loss in homes and buildings, leading to higher utility bills.

Thermal bridging generally occur when there is a break in or penetration of the building envelope. Thermal bridging can occur by the junctions between the wall and floor, the junctions between the wall and roof, holes in the building envelope for pipes and cables, window and door revels and sheet wall ties used in masonry construction.

It can increase the risk of condensation on internal surfaces and even cause interstitial condensation within walls and other building elements. Condensation forms when the interior temperature dips well below the dew point and moisture in warm air condenses into water droplets on cooler surfaces. In addition to heat transfer, if the indoor environment is not adequately vented, thermal bridging may cause the brick material to absorb rainwater and humidity into the wall, which can result in mould growth and deterioration of building envelope material.

So, thermal bridges should be avoided whenever possible. Proper planning, design and construction are essential to help identify and remedy thermal bridges. Care should be taken to ensure thermal bridging are not created at any point during the entire construction process.

There are some different kind of thermal bridging occur.

Repeating Thermal Bridges: This kind of thermal bridges follow a pattern and are “repeated” over an entire area of building’s thermal envelope. Repeating thermal bridges are both common and predictable, but can still cause a significant amount of heat loss. Therefore, this type of thermal bridge must be included in the U-value calculation and accounted for during planning, design and construction.

Non-Repeating Thermal Bridges: These thermal bridges occur periodically and are found where there’s a break in the continuity of the building’s thermal envelope. Non-repeating thermal bridges can also occur when materials with a different thermal conductivity meet to form part of the envelope.

Geometrical Thermal Bridges: Geometrical thermal bridges are indeed caused by the geometry of the building. Geometrical thermal bridges occur more frequently with complex building forms, so it’s best to keep the overall design as simplistic as possible to reduce their occurrence.

There are products and systems designed to help eliminate thermal bridging at common junctions, like an insulated foundation system. These passive foundation systems can help to eliminate the wall to floor cold bridge by wrapping the entire foundation in a layer of EPS, ensuring there are no breaks in the continuity of insulation. External wall insulation systems can also be extremely effective at minimising cold bridging.