recordRadiantSlabChar

Record containing all parameters for a given thermally activated building system (TABS) or a floor heating system.

Extends from Modelica.Icons.Record (Icon for records).

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.

Parameters

Type	Name	Default	Description
Boolean	tabs	true	= true, if the model is used for TABS (assuming no insulation layer below the slab).
Modelica.Units.SI.Length	T	0.2	Pipe spacing, limits imposed by EN 15377-3 p22
Modelica.Units.SI.Length	d_a	0.02	External diameter of the pipe
Modelica.Units.SI.Length	s_r	0.0025	Thickness of the pipe wall
Modelica.Units.SI.ThermalConductivity	lambda_r	0.35	Thermal conductivity of the material of the pipe
Modelica.Units.SI.Length	S_1	0.1	Thickness of the concrete/screed ABOVE the pipe layer
Modelica.Units.SI.Length	S_2	0.1	Thickness of the concrete/screed UNDER the pipe layer
Modelica.Units.SI.ThermalConductivity	lambda_b	1.8	Thermal conductivity of the concrete or screed layer
Modelica.Units.SI.SpecificHeatCapacity	c_b	840	Thermal capacity of the concrete/screed material
Modelica.Units.SI.Density	rho_b	2100	Density of the concrete/screed layer
Integer	n1	3	Number of discrete capacities in upper layer
Integer	n2	3	Number of discrete capacities in lower layer
Integer	nParCir	1	number of circuit in parallel
Modelica.Units.SI.ThermalConductivity	lambda_i	0.036	Heat conductivity of the insulation
Modelica.Units.SI.Length	d_i	0.05	Thickness of the insulation
Modelica.Units.SI.CoefficientOfHeatTransfer	alp1	3	Convective heat transfer coefficient between the floor layer and the room above
Modelica.Units.SI.CoefficientOfHeatTransfer	alp2	if tabs then 0.3 else lambda_i/d_i	Convective heat transfer coefficient between the floor layer and the room below. In case of a floor heating system, this variable is set equal to the ratio of the heat conductivity and thickness of the insulation

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.