The Modelica Buildings library 4.0.0 has been released on March 29, 2017.

Version 4.0.0 is a major new release. It is the first release that is based on the Modelica IBPSA Library ( All models simulate with Dymola 2017 FD01 and with JModelica, and the results of these simulators have been cross-compared and are equal within the expected tolerance.

The following major changes have been done:

  • It no longer uses the Modelica_StateGraph2 library. Instead, it uses Modelica.StateGraph which is part of the Modelica Standard Library.
  • The models in Buildings.Fluid.Movers have been refactored to increase the numerical robustness at very low speed when the fans or pumps are switched on or off.
  • The following new packages have been added:
    • Buildings.Experimental.DistrictHeatingCooling with models for district heating and cooling with bi-directional flow in the distribution pipes.
    • Buildings.Fluid.FMI.Adaptors and Buildings.Fluid.FMI.ExportContainers, which allow export of HVAC systems and of thermal zones as Functional Mockup Units.
    • Buildings.Fluid.HeatExchangers.ActiveBeams, with active beams for cooling and heating.
    • Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled, with water-cooled direct expansion cooling coils.
    • Buildings.ThermalZones.ReducedOrder, with reduced order models of thermal zones based on VDI 6007 that are suitable for district energy simulation.
  • The package Buildings.Rooms has been renamed to Buildings.ThermalZones.Detailed. This was done because of the introduction of Buildings.ThermalZones.ReducedOrder, which is from the Annex60 library, in order for thermal zones to be in the same top-level package.
    For Dymola, the conversion script will update models that use any model of the package Buildings.Rooms.
  • The model Buildings.Fluid.FixedResistances.FixedResistanceDpM has been refactored. Now, if the hydraulic diameter is not yet known, one can use the simpler model Buildings.Fluid.FixedResistances.PressureDrop, otherwise the model Buildings.Fluid.FixedResistances.HydraulicDiameter may be used. With this refactoring, also the model Buildings.Fluid.FixedResistances.SplitterFixedResistanceDpM has been renamed to Buildings.Fluid.FixedResistances.Junction and parameters that use the hydraulic diameter have been removed.
  • The models Buildings.HeatTransfer.Conduction.SingleLayer, Buildings.HeatTransfer.Conduction.MultiLayer, and Buildings.HeatTransfer.Windows.Window have been refactored to add the option to place a state at the surface of a construction. This leads in many examples that use the room model to a smaller number of non-linear system of equations and a 20% to 40% faster simulation.
  • The models Buildings.Fluid.HeatPumps.ReciprocatingWaterToWater and Buildings.Fluid.HeatPumps.ScrollWaterToWater have been added. Parameters to these models rely on calibration with tabulated heat pump performance data. Python scripts for the calibration of the heat pump models are in Buildings/Resources/src/fluid/heatpumps/calibration.