Junctions and thermal bridges

Junctions and thermal bridges

In a building that meets the Passivhaus Standard the junctions and interfaces require specific attention. It is at these points in the building fabric that heat loss can occur through thermal bridges; furthermore low surface temperatures can result in surface condensation and mould growth. Unaddressed thermal bridges can increase fabric heat loss by over 30%. This chapter considers the impact that thermal bridging and reduced surface temperatures can have upon building performance.

The concept of ‘zero thermal bridging’ can only be used successfully when using external dimensions. Due to geometry it is not possible to achieve zero thermal bridging using internal dimensions. The Passivhaus Standard considers a detail to be ‘...

User rating
0
No votes yet

There are essentially three types of thermal bridge:

• Repeating thermal bridges

• Linear thermal bridges: The Y-value (psi-value)

• Nodal thermal bridges: The X-value (chi-value)

Linear and nodal thermal bridges are...

User rating
0
No votes yet

It is possible to calculate thermal bridges using internal and external dimensions. The use of internal dimensions tends to underestimate heat loss. The use of external dimensions tends to overestimate heat loss. The two methods should not be...

User rating
0
No votes yet
Do
Inspect details prior to closing any openings, to ensure that the there are no gaps and discontinuities.
User rating
0
No votes yet
0 Comments
Do not improvise, read the drawings and specification or ask the design team if unclear.
User rating
0
No votes yet
0 Comments
Avoid gaps and discontinuities and ensure a clean working environment.
User rating
0
No votes yet
0 Comments
Protect insulation materials from mechanical damage and the weather.
User rating
0
No votes yet
0 Comments
Think of a reasonable dimension for a construction tolerance, and then double it.
User rating
0
No votes yet
0 Comments
Ensure that simple robust details are developed with adequate construction tolerance.
User rating
0
No votes yet
0 Comments
Design edges and corners to have as obtuse angles as possible. Pay specific attention to corners, ground floor/wall interfaces, eaves, verges, gable ends, structural openings (head, jamb and sill).
User rating
0
No votes yet
0 Comments
Minimise complexity – this reduces the chance of error and can assist buildability.
User rating
0
No votes yet
0 Comments
At the junction between building elements insulating layers should join without interruption or misalignment.
User rating
0
No votes yet
0 Comments
Where an unavoidable disruption is made to the insulating layer, the thermal resistance in the insulation should be as high as possible.
User rating
0
No votes yet
0 Comments

Pages