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--- basics:building_physics_-_basics:thermal_bridges:thermal_bridge_definition [2016/08/16 12:59] – [Additional heat losses] mschueren
+++ basics:building_physics_-_basics:thermal_bridges:thermal_bridge_definition [2016/08/16 13:02] – [Requirements] mschueren
@@ Line 85: / Line 85: @@
 Unlike with regular building components, at thermal bridges the heat flow density changes and usually results in a reduction in the surface temperature on the inside in that area. This effect is more pronounced because air circulation in corners and edges is restricted. Cupboards and other furniture not only disrupt convection but also restrict radiant exchange with the surroundings. Because the water vapour content of the air depends on its temperature, condensation may form on the affected areas.
-The resulting condensation can penetrate further inside the construction due to the capillary action of the building materials, and the thermal conductivity may increase and thus the building component may almost be saturated. It will not be possible to avoid moisture damage to the building structure and mould growth may occur. However, large-scale damage is generally associated with errors in the planning, implementation and utilisation of buildings and is not a problem that is solely related to thermal bridges. These are only the points where the problems originate in the first place. Nonetheless, the risk of mould fungus in the inner area of thermal bridges and the resultant toxic effect on occupants must be considered separately, especially since mould growth already occurs at a temperature higher than the dewpoint temperature without condensation being present. For a building physical analysis of the model, formation of mould can be assumed if relative surface humidity levels of 80 % prevail for a duration of 12 h/d   (Technical Report 4108-8).
+The resulting condensation can penetrate further inside the construction due to the capillary action of the building materials, and the thermal conductivity may increase and thus the building component may almost be saturated. It will not be possible to avoid moisture damage to the building structure and mould growth may occur. However, large-scale damage is generally associated with errors in the planning, implementation and utilisation of buildings and is not a problem that is solely related to thermal bridges. These are only the points where the problems originate in the first place. Nonetheless, the risk of mould fungus to the inner surface of thermal bridges and the resultant toxic effect on occupants must be considered separately, especially since mould growth already occurs at a temperature higher than the dewpoint temperature without condensation being present. For a building physical analysis of the model, formation of mould can be assumed if relative surface humidity levels of 80 % prevail for a duration of 12 h/d   (Technical Report 4108-8).
 ====Requirements====
-Requirements
+Requirements the current rules for engineering practice (DIN 4108-2) rule out the risk of mould near thermal bridges if the minimum surface temperatures under the mentioned steady-state boundary conditions do not fall below 12.6 °C. This corresponds with a $f_{Rsi}$ factor of 0.7:
-The current rules for engineering practice (DIN 4108-2) rule out the risk of mould near thermal bridges if the minimum surface temperatures under the mentioned steady-state boundary conditions do not fall below 12.6 °C. This corresponds with a $f_{Rsi}$ factor of 0.7:
 <WRAP center 60%>