Thermal insulation and moisture protection

The principle of the thermal assessment of a building is to record all energy gains and losses in balance procedures and to classify a building by means of the determined energy consumption.

Applicable requirements and regulations must be considered. Of fundamental importance for compliance with thermal and moisture protection is the consideration of the airtightness of the building shell.
The link between airtightness and thermal heat loss, indoor climate, summer heat protection, as well as the efficient prevention of moisture damage through convection, moisture ingress through leakages of outer planking is summarised in the regulations concerning thermal insulation/moisture protection as binding requirements for planning and executing the construction.

Heat insulation in winter

Targets:

  • Lowering the energy consumption of buildings in use
  • Reducing CO₂ emissions and the consumption of fossil/non-renewable resources
  • Remaining significantly below applicable national energy consumption thresholds (e.g., EnEV)

Measures:

  • Highly thermally insulated construction components. In addition, they offer a pleasant indoor climate, given that, based on the higher surface temperature of components, the air temperature in the rooms can be lowered and remains comfortable.
  • Passive house window construction, solar heat gains (south-west orientation)
  • Airtight building shell
  • Energy gains from, for example, sunlight (photovoltaic / solar heat), geothermal heat

Heat protection in summer

Targets:

  • Lowering energy consumption for air-conditioning/cooling systems
  • Avoiding the overheating of indoor spaces
  • Only delayed and attenuated transmission of solar heat into the interiors

Measures:

  • Construction materials with high weight, high specific heat capacity and low thermal conductivity for highly insulated exterior building components
  • Allowing for the external shading of the window construction, where applicable for south-west orientation, limiting the window surfaces on the roof
  • Airtight building shell
  • Using nocturnal cooling for ventilation
  • The rear ventilated cladding of exterior building components

Terms:

  • Specific thermal capacity (material heat) c: indicates which amount of heat (J, Wh, kJ) per kilogram of material can be absorbed at 1 K temperature difference:

    Specific heat capacity c
    • Wood → 0.69 Wh/kg*K
    • Concrete → 0.24 Wh/kg*K
    • Glass wool → 0.23 Wh/kg*K
    • Cellulose → 0.60 Wh/kg*K
       
  • Amplitude attenuation ν / νH: indicates to what extent the summer temperature fluctuations are attenuated from the outside to the inside: ν / νH = ϑ a / ϑ i (ϑa = temperature amplitude outside; ϑ i = temperature amplitude inside)
     
  • Phase shift ηH: specifies the time shift between reaching the temperature amplitude outside and inside.
     
  • Heat penetration coefficient a’:
    quantifies the subjective perception that surfaces feel “warm” or “cold” despite equal temperature: a’ = a’ = λ /(ρ * c)
     
  • Thermal diffusivity b: Measures how quickly high outside temperatures, e.g., due to sunlight, can penetrate a material: b = √ λ ∗ ρ ∗ χ
Basics of timber construction