Integrated district energy assessment by simulation (IDEAS)

Increasingly more buildings and building districts combine several energy sources, both renewable and fossil, with different energy carriers such as electricity and heat. As a result, the integration and interactions of these different sources and carriers become more interwoven. EnergyVille developed its Integrated District Energy Assessment by Simulation library (IDEAS) to effectively evaluate the functionality of these complex energy systems in all its facets. This comprehensive Modelica library allows to model individual buildings and neighbourhoods for energy and thermal comfort simulations.

With IDEAS, the integration, interaction, control and feedback of buildings, district systems and multidisciplinary energy systems, can be assessed in one single simulation model and solver, taking into account building physics aspects, electrical systems, thermal heating, ventilation and air conditioning systems,… IDEAS enables a flexible use of the different models. They can be separately simulated in their respective domains and they can be combined for energy system integration.

Key benefits

  • Multidisciplinary assessments of energy systems in buildings and districts/neighbourhoods
  • User-friendly: documented models, examples available, parameter studies
  • Post processing and reporting possible in simulation environment (s.a. Dymola) or other tools (s.a. Python and Matlab)
  • Data available in the library based on scientific literature or data sheets. User can overwrite or add new data
  • Detailed models available
  • Granularity: output time scale can be chosen; input data with different time scales can be handled

A schematic overview of the IDEAS tool (R. Baetens, R. De Coninck, J. Van Roy, B. Verbruggen, J. Driesen, L. Helsen, and D. Saelens, “Assessing electrical bottlenecks at feeder level for residential net zero-energy buildings by integrated system simulation,” Applied Energy, vol. 96, pp. 74–83, Aug. 2012.)

IDEAS contains three different domains which can be simulated separately or can be used for energy system integration:

  • Transient building response: simulate the energy demand for heating and cooling, and thermal energy flows in a multi-zone building.
  • Thermal building systems: simulate the thermal energy production (boiler, heat pump, ideal heating,…), domestic hot water production, ventilation systems, the thermal energy distribution, thermal energy storage and heat emission (radiator, floor heating,…).
  • Electricity system: simulate consumption, renewable photovoltaic production, electrical energy storage and distribution (unbalanced three-phase grids) of electricity in buildings and districts.


    • Design of multi-domain energy systems: buildings and district
      • Analyse, optimise and control of subsystems and combined energy systems
      • Custom case studies
    • Distribution grid impact assessments of multidomain energy systems
      • Grid impact assessment and control of appliances with grid variables
      • Custom case studies
    • Open-source library, incl. support
      • Library development: custom-made models
      • Validation of f.e. appliance measurements with custom-made models


  • Building project developers
  • Engineering offices: building designers, thermal and electrical engineering
  • Researchers
  • Distribution grid operators
  • Energy advisers
  • Manufacturers for thermal and electrical systems


The IDEAS library is implemented in the Modelica modelling language, which is open-source, object-oriented and equation-based. Modelica is well-suited for physical modelling and offers an easy integration of different domains in a single model. IDEAS is available as an open-source library; IDEAS v1.0 and other development versions are available online at: (link is external)

A large part of the library is already well-documented, and a manual is available describing the specifications, model descriptions, validation and verification results. Various scientific publications describe the different libraries and models. The developers of IDEAS are also linked to the IEA EBC Annex 60 regarding “New generation computational tools for building and community energy systems based on the Modelica and Functional Mockup Interface standards”.

Want to know how the IDEAS Library can support you? Feel free to contact one of our experts.

Dirk Saelens, Professor Building Physics at EnergyVille/KU Leuven

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