The following table shows various areas of construction where thermal bridging often occurs and ways to break the thermal bridging:
Areas of potential thermal bridging and strategies to reduce thermal bridges
Area of potential thermal bridging |
Description |
Strategies to reduce thermal bridges |
Roof-to-wall interface |
Typically happens in parapets, extended terrace construction in multi-storeyed buildings and penthouses |
Achieve thermal continuity by extending the roof insulation to the wall |
Steel stud construction |
In all types of steel stud structural construction |
A continuous thermal barrier using the full value of required insulation outboard of the studs |
Window-to-wall interface |
Occurs around windows and doors |
Align the window frame with the insulation and use low conductivity plastic or urethane material frames |
Wall-to-balcony/sunshade slab interface |
All projecting balconies and other elements such as shades |
Construct separate exterior and interior elements with a thermal buffer in between, typically using proprietary systems |
Wall-to-wall interface |
Occurs when different wall types interest. For example, a cavity wall with a precast wall |
Lapping the insulation beyond the plane of the all |
Wall-to-foundation interface |
Occurs along the perimeter of the plinth foundation and other structural to masonry joints |
Use load bearing perimeter insulation |
Totten, O'Brein, & Pazera, 2016
The heat transmission losses due to thermal bridging are usually accounted for in heat loss calculations in either simplified or detailed ways. Simplified approach can be done by simple hand calculations while the detailed 2-dimensional or 3-dimensional thermal bridging effects are calculated by performing numerical analysis. The simplified approach in the Netherlands for example, requires the addition of a correction factor to the actual U value of the element ( ca ΔU = 0.10 W/m2K) while the detailed calculations can be performed using ISO standards ISO 10211:2007 to accurately determine the value of ‘linear thermal bridge’. Building regulations in Denmark specifies the value of linear thermal bridge which ranges from 0.03 W/mK for windows to 0.15 W/mK for foundations in retrofits and from 0.06 W/mK for window fittings up to 0.40 W/mK for foundations in new buildings. Detailing out thermal bridging in both design, construction and execution required special understanding of the subject, the us of specialised components and the skills to layout the components correctly during construction (Citterio, Cocco , & Erhorn-Kluttig, 2008).