Thermal bridges can occur wherever a poor conductivity material bridges the insulation layer of a construction, resulting in additional heat lost through that bridge.
There are three types of thermal bridging that can be considered for buildings:
1. Repeating thermal bridges
U-value calculations for planar elements should take account of the effect of repeating thermal bridges e.g. a 15% steel bridging fraction might be taken for studs in a steel framed wall. Our literature states where we have taken these into account.
2. Linear (non-repeating) thermal bridges
Linear thermal bridging describes the heat gains that occur at junctions between elements. This can include for example, junctions at corners, where external walls join with the floor, or where external walls are bridged by lintels, jambs or sills where window or door openings are installed.
3. Point thermal bridges
A third type of thermal bridge, point thermal bridging may also be calculated and is occasionally used as an adjustment to a U-value for an element, this might be used as an adjustment to a planar U-value to take account of fixings or fasteners, or possibly as an adjustment for isolated steel beams or columns.