modelRadiantHeatingCooling_TRoom

Information

Model that uses EnergyPlus for the simulation of a building with one thermal zone that has a radiant ceiling, used for cooling, and a radiant floor, used for heating. The EnergyPlus model has one conditioned zone that is above ground. This conditioned zone has an unconditioned attic. The model is constructed by extending Buildings.ThermalZones.EnergyPlus_24_2_0.Examples.SingleFamilyHouse.HeatPumpRadiantHeatingGroundHeatTransfer and adding the radiant ceiling. For simplicity, this model provide heating with an idealized heater.

The next section explains how the radiant ceiling is configured.

Coupling of radiant ceiling to EnergyPlus model

The radiant ceiling is modeled in the instance slaCei at the top of the schematic model view, using the model Buildings.Fluid.HeatExchangers.RadiantSlabs.ParallelCircuitsSlab. This instance models the heat transfer from the surface of the attic floor to the ceiling of the living room. In this example, the construction is defined by the instance layCei. (See the Buildings.Fluid.HeatExchangers.RadiantSlabs.UsersGuide for how to configure a radiant slab.) In this example, the surfaces slaCei.surf_a (upward-facing) and slaCei.surf_a (downward-facing) are connected to the instance attFlo. Because attFlo models the floor of the attic, rather than the ceiling of the living room, the heat port slaCei.surf_a is connected to attFlo.heaPorFro, which is the front-facing surface, e.g., the floor. Similarly, slaCei.surf_b is connected to attFlo.heaPorBac, which is the back-facing surface, e.g., the ceiling of the living room.

The mass flow rate of the slab is constant if the cooling is operating. A P controller computes the control signal to track a set point for the room temperature. The controller uses a hysteresis to switch the mass flow rate on or off. The control signal is also used to set the set point for the water supply temperature to the slab. This temperature is limited by the dew point of the zone air to avoid condensation.

See also the model Buildings.ThermalZones.EnergyPlus_24_2_0.Examples.SingleFamilyHouse.RadiantHeatingCooling_TSurface which is controlled to track a set point for the surface temperature.

Coupling of radiant floor to EnergyPlus model

The radiant floor is modeled in the instance slaFlo at the bottom of the schematic model view, using the model Buildings.Fluid.HeatExchangers.RadiantSlabs.ParallelCircuitsSlab. This instance models the heat transfer from surface of the floor to the lower surface of the slab. In this example, the construction is defined by the instance layFloSoi. (See the Buildings.Fluid.HeatExchangers.RadiantSlabs.UsersGuide for how to configure a radiant slab.) In this example, the surfaces slaFlo.surf_a and slaFlo.surf_b are connected to the instance flo. In EnergyPlus, the surface flo.heaPorBac is connected to the boundary condition of the soil because this building has no basement.

Note that the floor construction is modeled with 2 m of soil because the soil temperature in EnergyPlus is assumed to be undisturbed.

Parameters

Components

Contents

Name	Description
MediumW	Water medium

Revisions

• March 13, 2024, by Michael Wetter:
  Updated idf file to add insulation, and resized system.
  This is for issue 3707.
• December 1, 2022, by Michael Wetter:
  Increased thickness of insulation of radiant slab and changed pipe spacing.
• March 30, 2021, by Michael Wetter:
  First implementation.