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--- basics:building_physics_-_basics:heat_transfer [2016/07/26 12:07] – sahmed
+++ basics:building_physics_-_basics:heat_transfer [2020/09/12 13:02] – wfeist
@@ Line 1: / Line 1: @@
 ====== Heat transfer ======
-Heat transfer is the transfer of thermal energy across a thermodynamic system boundary (the building envelope in the case of a Passive House building) as a result of a temperature difference. The energy transferred in this way is referred to as "heat" and is a value of this process. The direction of heat transfer is always from a warmer area towards a colder area, in other words: heat transfer always strives for an energy balance across system boundaries.
+Heat transfer is the transfer of thermal energy across a thermodynamic system boundary (the building envelope in the case of a Passive House building) as a result of a temperature difference. The energy transferred in this way is referred to as "heat". The direction of heat transfer is always from a warmer area towards a colder area, in other words: heat transfer always strives for an energy balance across system boundaries.
-The physical dimension for the extent of heat transfer is the heat flow rate, that is the power which passes through a square metre of a surface which is perpendicular to a surface measured in W/m² (watts per square metre). As a rule the heat flow rate (at least with small temperature differences) is proportional to the difference between the temperatures. If divided by the temperature difference, the result will be a value which characterises the heat transfer capacity of the envelope surface of the building component: this is the thermal transmittance or U-value. This is measured in W/(m²K) (watts per square metre per kelvin), whereby a temperature difference of 1 K is exactly the same as a temperature difference of 1 °C.
+The physical dimension for the extent of heat transfer is the heat flow rate, that is the power which passes through one unit of area of a surface perpendicular to it measured in W/m² (Watts per square metre). As a rule the heat flow rate (at least with small temperature differences) is proportional to the difference between the temperatures. If divided by the temperature difference, the result will be a value which characterises the heat transfer capacity of the envelope surface of this building component: this is the thermal transmittance coefficient or U-value. This is measured in W/(m²K) (Watts per square metre per Kelvin), whereby a temperature difference of 1 K is exactly the same as a temperature difference of 1 °C.
-  * [[basics:building_physics_-_basics:heat_transfer:what_defines_thermal_bridge_free_design|What defines thermal bridge free design? ]]
+  * [[basics:building_physics_-_basics:what_defines_thermal_bridge_free_design]]
   * [[planning:thermal_protection:don_t_save_on_the_insulation ]]