.BuildSysPro.Building.BuildingEnvelope.HeatTransfer.SimpleWall

Information

Wall simple linear model

Hypothesis and equation

This is a model of a simple wall. A conductive heat transfer occurs in the material which is defined by n homogeneous layers (each layer is discretized into equal sized meshes). Convective heat transfers occur on the two faces, internal and external.

Input solar fluxes with short wavelength (SWR) are absorbed at the surface considering the parameters AbsParoi. This is the overall surface flux.

In case of long wavelength (LWR), exchanges are linearized with the model LinearExtLWR. The parameter skyViewFactor determines the share of SW radiation of the wall with the sky, considered at T_sky, and the external environment, considered at T_ext.

This model leads to a linear time-invariant model that can be reduced.

Bibliography

TF1 CLIM2000 modified in order to obtain a linear time-invariant model for the purposes of cities study.

Instructions for use

This wall can be an outer or inner wall.

The thermal ports T_ext and T_int must be connected to temperature nodes (connect T_ext to T_dry of Meteofile). The external incident flows FluxAbs can come from the solar boundary conditions model SolarBC.

The internal incident flows FluxAbsInt can come from occupants, heating systems but also from the redistribution of solar flux within a room (models from BoundaryConditions.Radiation package).

Known limits / Use precautions

Warning, default values of convective coefficients are indicative only, and should not be taken as real values in all cases.

The given exchange coefficients can be either global coefficients (sum of convective and radiative), or purely convective exchanges if radiative exchanges are treated elsewhere.

• If GLOext = True, then hs_ext is a purely convective coefficient
• 5,15 W/m².K outside and 5.71 W:m².K inside can be removed from the value of the recommended global exchange coefficient.

Some indications :

• Vertical surfaces: hs_int = 7.69, hs_ext = 25
• Horizontal surfaces: hs_int = 10, hs_ext = 25

Validations

Validated model - Gilles Plessis 03/2012

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Licensed by EDF under a 3-clause BSD-license
Copyright © EDF 2009 - 2023
BuildSysPro version 3.6.0
Author : Gilles PLESSIS, EDF (2012)
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Revisions

Amy Lindsay 03/2014 : changement des FluxSolInput en RealInput pour les flux absorbés intérieur pour éviter les confusions (ces flux absorbés en GLO ou en CLO peuvent non seulement provenir du soleil, mais aussi d'autres sources radiatives)

Mathias Bouquerel 07/2019 : the calculation of the wall U-value is added (takes into account the wall composition and heat transfer coefficients).