How to minimise heat loss at thermal bridges

Linear thermal bridges can account for 20-30% of the heat loss in a typical new build home but building with aircrete can minimise the impact.

How to reduce heat loss in our homes is currently a hot topic, and answers typically start with better insulation. But, as homes become increasingly better insulated, addressing the heat loss that results from a structure’s thermal bridging will become more of a focus for those designing and specifying our homes.

There are two types of thermal bridges: non-repeating (or linear) and repeating. Repeating thermal bridges are usually evenly distributed across the building envelope and follow a regular path. Sources of these types of thermal bridge include insulation bridged by cavity wall ties, stud walls and mortar joints. 

Non-repeating thermal bridges are caused by discontinuities in the building envelope and occur at junctions between elements such as a wall and a floor or a window and a wall. Where any thermal bridge occurs in a build, heat is more able to transfer through the construction, resulting in greater heat loss from the building. 

The relative effects of non-repeating thermal bridging become more significant as homes become better insulated. When U-values are reduced, heat losses due to non-repeating thermal bridges can account for up to 50% of the fabric heat loss so understanding how to build to minimise this is crucial.

Using aircrete can significantly reduce the thermal bridge effect at junctions, as it has better thermal resistance than dense materials. 

Aircrete blocks used in separating walls can achieve added thermal benefits and limit heat loss at junctions with external elements. When used in conjunction with aircrete inner leaves, heat losses at thermal bridges can be reduced by around 50%. 

Choosing to build with aircrete, instead of framed construction, allows CO2 emission targets to be more easily met or savings to be made on other parts of the insulated fabric without compromising a dwelling's thermal performance. And it can be equivalent to the effect of adding 10-15mm of insulation to the external walls.

For more information on thermal bridges, how to calculate them and useful technical resources, visit our page on thermal linear bridging