Thermal Bridges

Thermal bridges are very common in old houses or houses with insufficient insulation. The affected part of the construction results to a significantly higher heat transfer than the surrounding materials resulting in an overall reduction in thermal insulation of construction. Partially insulated building elements are responsible for up to 35% of thermal losses and increased condensation that leads to mold growth.

Thermal bridges can be classified into three main types (Leeds Beckett University: Low Carbon Housing Learning Zone):

  1. Repeating or quasi-homogeneous thermal bridges usually follow a regular pattern and are evenly distributed over an area of the thermal envelope
  2. Non-repeating or linear thermal bridges are often caused by discontinuities in the thermal envelope and occur at a specific point in the construction
  3. Geometrical thermal bridges are a result of the geometry or shape of the thermal envelope

Στιγμιότυπο 2015-11-17, 12.41.45

The most common parts of a construction where the thermal bridges can occur are:

  • The parts of the building envelope that are exposed to the external environment and have different thermal conductivity
  • The parts where a change in the thickness of the fabric occurs
  • The wall-floor-ceiling junctions of the building where there is a difference between internal and external areas

 

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To avoid thermal bridging you should provide your house with enough insulation at the affected parts such as:

  • Concrete balconies that extend the floor slab through the building envelope.
  • Areas around glazing, window frames and rooflights
  • Metal ties in masonry cavity external walls
  • Ceiling joists in cold pitched roofs
  • Ground floor joists in an insulated suspended timber ground floor
  • Timber studwork and I-beams in timber frame constructions
  • Mortar joints in an insulating block inner leaf
  • Areas round loft hatches
  • Wall/ roof junctions or wall/ floor junctions
  • At the corner of an external wall
  • Junctions between adjacent walls

There are many strategies and methods that the builder should follow to avoid thermal bridges:

  • Apply a continuous layer of insulation around the external walls of you house such as expanded polysteryne or mineral wool insulation.
  • By adding insulation at the outside corner of your building where the walls and floor are connected

By reducing thermal bridges you will have saved a great amount of heat losses and energy needs of your home resulting in reduced energy bills and increased building lifespan.