.IDEAS.Fluid.HeatExchangers.RadiantSlab.BaseClasses.RadiantSlabChar

Information

Record containing the properties of a thermally activated building system (TABS) or floor heating system. The terminology from EN 15377 is followed, while the EmbeddedPipe model itself is based on the model of Koschenz and Lehmann.

Note that this record contains parameters that are related to the building envelope, i.e. construction layer thicknesses and material properties. The user is responsible to use consistent parameters for the building envelope components and the embedded pipe model. When filling in the parameters, take into account that:

• the insulation parameters (lambda_i, d_i) only need to be provided if you model a floor heating system (if tabs=false)
• the convective heat transfer coefficients (alp1 and alp2) only need to be provided if S_1 and/or S_2 are smaller or equal to 0.3 times the pipe spacing (T).
• the floor layer thicknesses (S_1, S_2) and pipe diameter (d_a) are subject to some constraints, which are checked in the EmbeddedPipe model, i.e.:
  • d_a ≥ S_1+S_2
  • if tabs=false, then alp2 ≥ 1.212
  • if tabs=false, then d_a/2 ≥ S_2

The default values of convective heat transfer coefficients alp1 and alp2 (in case of tabs=true) are determined using the interior convection correlations as provided in the documentation of IDEAS.Buildings.Components.BaseClasses.ConvectiveHeatTransfer.InteriorConvection, for a room of 25 m² and a temperature difference between the slab and the room of 5°C. If tabs=false, alp2 is set equal to λ_i / d_i, which is a valid assumption since the conductive thermal resistance of the floor heating's insulation is significantly higher than the convective thermal resistance between the slab's surface and the room.

References

EN 15377, Heating systems in buildings – Design of embedded water-based surface heating and cooling systems, 2008.

M. Koschenz and B. Lehmann, Thermoaktive Bauteilsysteme tabs. Dübendorf, Switzerland: EMPA Energyiesysteme/Haustechnik, 2000, ISBN: 9783905594195.

Revisions

• August 12, 2025, by Jelger Jansen:
  Add convective heat transfer coefficient alp1, update default value of alp2, and update documentation.
  See #1381.
• May, 2013, by Roel De Coninck:
  Add documentation.
• June, 2011, by Roel De Coninck:
  First implementation.