3D Thermal FEM Analysis of Windows Frame

In this renovation project, with the use of 3D Thermal FEM analysis, we verified the absence of the thermal bridge in the windows frame.

Variables definition

• Regulations: UNI EN 13788:2013
• Average outside temperature of the coldest month: +4.1°C
• Internal temperature: +20°C

The counterframe of the window will be fixed to the wall by means of L-shaped steel point brackets with a triangular reinforcement in the middle. For the sake of completeness of the analysis, the verification of the node will be made in the three possible conditions:

1. Zone in the absence of the bracket;
2. Zone with the bracket, without the reinforcement;
3. Area with the bracket, in the presence of the reinforcement.
4. An overall 3D simulation was also performed by combining the 3 previously defined 2D conditions in superimposed layers in order to obtain a representative model of the real case.

2D simulation results

1 – Area without bracket
Isotherm 12.6 ° C (red line-point) and minimum temperature point (15.29 ° C) were highlighted.

2 – Bracket area without reinforcement
Isotherm 12.6 ° C (red line-point) and minimum temperature point (13.52 ° C) were highlighted.

3 – Area with bracket and reinforcement
Isotherm 12.6 ° C (red line-point) and minimum temperature point (13.03 ° C) were highlighted.

3D simulation results

Below is the trend of the isotherms resulting from the 3D analysis of the defined model. The image represents the trend of temperatures limited to those greater than 12.6 ° C. The point with minimum surface temperature (13.99 ° C) is in correspondence with the layer containing the reinforcement plate of the subframe fixing bracket.

The results of the 3D analysis are comparable to those obtained from two-dimensional simulations, thus confirming their validity.