Wood spans thermal bridges
Thermal conductivity is used to measure the insulation properties of building material. The lower the thermal conductivity, the better the building material will insulate. A brief example will illustrate the enormous differences:
Reinforced concrete: thermal conductivity 2.30 W/(mK)
Construction timber: thermal conductivity 0.13 W/(m/K)
Cellulose insulation: thermal conductivity 0.039 W/(m/K)
Thermal bridges are areas where for example more heat is lost through a switch in materials than in neighbouring structural elements. Thanks to the low thermal conductivity of wood the thermal bridge effect of wooden structural elements is very slight. Any thermal bridges that arise can be minimised with the help of simple constructional measures.
With customary wall and roof construction, supporting elements (wood parts) that are used regularly alternate with highly effective insulation materials. The factor that determines the influence of thermal bridges for wooden constructions is thus the proportion of construction timber in the structural elements.
Insulation and thermal protection
Wood frame constructions have very good insulation properties since the supporting structure and the insulation material are in the same plane and almost all the cross-section of the wall can be used for thermal protection. Additional layers of insulation material e.g. on the outside or an insulated installation section on the inside enable insulation levels to be attained that are required in a passive house (heating requirement of < 0.15 kW/m²). An overall structural element thickness of 30 cm is already sufficient to attain this passive house standard.