Thermal Bridging

I remember seeing a ladies’ sheepskin coat that had no buttons on the front.  The sheepskin coat is one of the warmest winter coats, but only if it is buttoned up. If it is left unbuttoned then it is not as effective. On a cold day you might try and rap it all the way around but it will never really be quite as warm without being tightly fastened at the front, as it was designed to be.

Good thermal bridging has become more important in SAP 2012 Heat follows the path of least resistance and that means that an awful lot of heat can come out of a small gap. This is certainly the case with thermal insulation. When you fit insulation you are doing the same thing.  Gaps in a building are created where a wall meets a roof, a floor, or another wall etc. Even when  the quality of the building work is good and the insulation itself has been fitted carefully gaps are still a problem.  Fitting the insulation with no gaps and producing a structure that is airtight does not guarantee good thermal bridges.  A large proportion of the building’s heat can be lost from areas at the corners that are so small you might be tempted to forget about them.

Your thermal bridges affect the thermal performance of the finished building more than any other single aspect of building design.

Using good thermal bridging has become more important in SAP 2012 as we now have a Fabric Energy Efficiency.

The structure of the building has got to have a very high thermal efficiency itself. You won’t pass the SAP test by making a few mistakes and then sticking a few solar panels on the roof to compensate for the increased CO2.

Accredited Construction Details Accredited Construction Details (ACDs) are the normal way of overcoming this problem of thermal bridging.  A full set of diagrams with tick boxes are available on Planning Portal for free download. http://www.planningportal.gov.uk/buildingregulations/approveddocuments/partl/bcassociateddocuments9/acd