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--- basics:building_physics_-_basics:thermal_bridges:tbcalculation:basic_principle_for_calculating_thermal_bridges [2016/08/02 15:56] – [Example of a thermal bridge calculation] mschueren
+++ basics:building_physics_-_basics:thermal_bridges:tbcalculation:basic_principle_for_calculating_thermal_bridges [2022/02/15 19:12] (current) – admin
@@ Line 5: / Line 5: @@
 ===== Determining the thermal transmittance =====
-The principle for calculating the linear thermal transmittance is depicted in the illustration below. The $\Psi$-value represents the difference between the thermally interrupted component and the uninterrupted component that is assumed for the balance. First the heat flow or the conductance $L_{2d}$ is determined by means of the heat flow simulation. To determine the $\Psi$-value, $L_{0}$ is deducted from the conductance of the uninterrupted building component. It is essential that the linear reference is adhered to all throughout. If interior references are used in the context of energy balancing, then $\Psi$-values based on interior references must also be used. However, exterior dimensions are used more often in practice as these can easily be taken from plans and measurements. Exterior dimensions are therefore consistently used in the [[planung:energieeffizienz_ist_berechenbar:energiebilanzen_mit_dem_phpp|PHPP]].
+The principle for calculating the linear thermal transmittance is depicted in the illustration below. The $\Psi$-value represents the difference between the thermally interrupted component and the uninterrupted component that is assumed for the balance. First the heat flow or the conductance $L_{2d}$ is determined by means of the heat flow simulation. To determine the $\Psi$-value, $L_{0}$ is deducted from the conductance of the uninterrupted building component. It is essential that the linear reference is adhered to all throughout. If interior references are used in the context of energy balancing, then $\Psi$-values based on interior references must also be used. However, exterior dimensions are used more often in practice as these can easily be taken from plans and measurements. Exterior dimensions are therefore consistently used in the [[planning:tools|PHPP]].
 {{ :picopen:psicalculation.png?600 |}}
@@ Line 33: / Line 33: @@
   * $\theta_e$ = −5 °C for outdoor air temperature
-The Passive House Institute uses the following boundary conditions for the temperature in teh context of **[[certification:passive_house_suitable_components|Componenten certification]]**:
+The Passive House Institute uses the following boundary conditions for the temperature in the context of **[[certification:passive_house_suitable_components|Component certification]]**:
   * $\theta_i$ = 20 °C for indoor air temperature
@@ Line 41: / Line 41: @@
 <WRAP center 60%>
-<latex>
+\begin{align}
-\begin{equation*}
+&f_{Rsi}(x,y,z)=\dfrac{\theta_{min}(x,y,z)-\theta_e}{(\theta_i-\theta_e)} \qquad \text{or } \qquad f_{Rsi}(x,y)=\dfrac{\theta_{min}(x,y)-\theta_e}{(\theta_i-\theta_e)}\\\\
-f_{Rsi}(x,y,z)=\dfrac{\theta_{min}(x,y,z)-\theta_e}{(\theta_i-\theta_e)} \qquad \text{bzw. } \qquad f_{Rsi}(x,y)=\dfrac{\theta_{min}(x,y)-\theta_e}{(\theta_i-\theta_e)} \label{eq:frsi}
+With\qquad&\\
-\end{equation*}
+f_{Rsi}\qquad&\text{the temperature factor at the location $(x,y,z)$ or $(x,y)$}\\\\
-	\begin{tabular}{ll}
+\theta_{min}\qquad&\text{the minimum surface temperature at the location $(x,y,z)$ or $(x,y)$}\\\\
-	where & \\
+\theta_i\qquad&\text{indoor air temperature}\\\\
-	$f_{Rsi} $ 	& the temperature factor at the location $(x,y,z)$ bzw. $(x,y)$ \\
+\theta_e\qquad&\text{outdoor air temperature}\\
-	$\theta_{min}$ 		&  the minimum surface temperature at the location $(x,y,z)$ bzw. $(x,y)$ \\
+\end{align}
-	$\theta_i$ 		& indoor air temperature \\
-	$\theta_e$ 		& outdoor air temperature \\
-	\end{tabular}
-</latex>
 </WRAP>
@@ Line 61: / Line 57: @@
 A thermal bridge calculation for a verge detail is shown below.
-{{ :picopen:wb_ortgang_beispiel.png?nolink&800 |}}
+{{ :picopen:wb_ortgang_beispiel.png?direct |}}