Validation Case: Thermal Bridge Case 3 – 3D Corner in Building Construction

This validation case belongs to heat transfer, with the case of a three-dimensional corner where two walls and one floor element meet. The aim of this project is to demonstrate the validity of SimScale’s Heat Transfer solver by replicating the standard test case and comparing the following parameters:

Temperature distribution

The simulation results from SimScale were compared to the reference results presented in the standard EN-ISO 10211, “Thermal Bridges in Building Construction”, validation case 3 (Annex C)\(^1\).

The structural corner geometry is shown in figure 1:

The model is composed of the following parts:

Floor

Horizontal structure (which acts as the thermal bridge)

Internal wall – upper

Internal wall – lower

External wall

Insulation

For the application of boundary conditions and measurement of result quantities, the surfaces of the structure are classified according to the spaces they belong to:

The mesh was computed using SimScale’s standard meshing algorithm, with the fineness parameter maxed up to 10. Statistics of the resulting mesh are presented in Table 1, and illustration shown in Figure 2:

The model considers convective heat transfer from the surfaces of the structure to the corresponding spaces. The interior spaces are at 20\(°C\) and 15\(°C\), and the exterior is at 0\(°C\). Also, the standard specifies the heat transfer properties in terms of the thermal resistance \(R\), which must be converted to the heat transfer coefficient used in SimScale, according to:

$$ h = \frac{1}{R} $$

The following boundary conditions were used in the simulation (see Figure 2 for illustration):

Lower internal faces \(\alpha\):

Convective heat flux

(\(T_0\)) Reference temperature 20\(°C\)

Heat transfer coefficient 5 \(W/(K.m^2)\)

Upper internal faces \(\beta\):

Convective heat flux

(\(T_0\)) Reference temperature 15\(°C\)

Heat transfer coefficient 5 \(W/(K.m^2)\)

External faces \(\gamma\):

Convective heat flux

(\(T_0\)) Reference temperature 0\(°C\)

Heat transfer coefficient 20 \(W/(K.m^2)\)

Structure cuts \(\delta\):

Adiabatic (applied by default)

Reference Solution

The reference solution\(^1\) for the structure is given in terms of the minimum temperatures and heat fluxes at the control surfaces.

Result Comparison

The computed temperature values from the simulation are presented in Table 2, and compared to the expected values from the standard:

Result

Reference Value

SimScale Value

Deviation

Minimum temperature on \(\alpha\)

11.32\(°C\)

11.29\(°C\)

0.03\(°C\)

Minimum temperature on \(\beta\)

11.11\(°C\)

11.12\(°C\)

0.01\(°C\)

Table 2: Results comparison for the quantities of interest

The acceptance criterion states that the difference between the computed temperatures by the method being validated and the listed temperatures shall not exceed 0.1\(°C\). Thus, it is found that the SimScale solver is accepted under the standard’s validation case 3.

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