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ISO 10211:2007 Thermal bridges in building construction. Test case A.3 validation

QuickField 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 R_s is caused by the convection. The convection coefficient value is reciprocal to the surface resistance value:
α = 1 / R_s [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

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.