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Applications >> Sample problems >> Thermal bridges in building construction. Test case 3 validationQuickField validation of the test case A.3 presented in ISO 10211:2007 Thermal bridges in building construction.
Problem Type:
3D problem of heat transfer.
Geometry:
all length units are in millimeters.
Given:
Thermal conductivity of AAC λ1 = 0.7 W/K·m.
Thermal conductivity of insulation λ2 = 0.04 W/K·m.
Thermal conductivity of brick λ3 = 1.0 W/K·m.
Thermal conductivity of concrete slab λ4 = 2.5 W/K·m.
Thermal conductivity of plaster λ5 = 1 W/K·m.
Problem:
The floor slab penetrates the wall near the corner and forms the cold bridge. Determine the flux and the thermal coupling coefficients.
Solution:
Air contact surface thermal resistance Rs is caused by the convection. The convection coefficient value is reciprocal to the surface resistance value:
α = 1 / Rs [W/(K·m2)].
Results:
Temperature distribution in media (click to see 3D view):
Temperature in the corners: |
QuickField |
Reference |
%% |
First floor |
11.12°C |
11.11°C |
<0.1 K |
Second floor |
11.37°C |
11.32°C |
<0.1 K |
Heat flux: |
59.4 W |
59.98 W |
1% |
Thermal coupling coefficients (reference values are in the brackets).
External |
First floor |
Second floor |
|
External |
(1.000) |
(0.000) |
(0.000) |
First floor |
0.375 (0.378) |
0.401 (0.399) |
0.223 (0.223) |
Second floor |
0.329 (0.331) |
0.216 (0.214) |
0.455 (0.455) |
To comply with the ISO 10211:2007 the difference between calculated and reference heat flux should be less than 2% (0.1°K - for temperature). This simulation accuracy complies with the requirements of ISO 10211:2007.
*ISO 10211:2007(en) Thermal bridges in building construction - Heat flows and surface temperatures - Detailed calculations.