Research-backed optimisation for complex energy planning.
Sympheny's optimisation engine is built on a decade of Empa and ETH Domain research in multi-energy system modelling: MILP optimisation, district heating layout, grid constraints, clustering, and decision-grade scenario comparison.
The papers behind the optimisation engine
These are the papers most useful for understanding why Sympheny's modelling approach is credible, inspectable, and practical for real planning work.
Ten questions concerning modeling of distributed multi-energy systems
Georgios Mavromatidis, Kristina Orehounig, L. Andrew Bollinger, Marc Hohmann, Julien F. Marquant, Somil Miglani, Jan Carmeliet | Building and Environment, 2019
A field-defining review co-written by two Sympheny founders and the wider Empa group. It sets out the core modelling questions for distributed multi-energy systems - technology choice, temporal and spatial resolution, uncertainty, and optimisation - and is one of the most-cited references for why this class of problem needs a structured optimisation approach rather than a spreadsheet.
Platform-based design for energy systems
Matthias Sulzer, Michael Wetter, Robin Mutschler, Alberto Sangiovanni-Vincentelli | Applied Energy, 2023
Primary reference for the structured-design argument: energy systems need reusable, digital, multi-layer workflows because sector coupling and distributed resources make manual planning too complex. The paper includes a public Modelica/Sympheny district dataset.
Optimization-based planning of local energy systems - bridging the research-practice gap
Andrew Bollinger, Julien Marquant, Matthias Sulzer | IOP Conference Series: Earth and Environmental Science, 2019
Foundational practice paper for Sympheny's product logic. It identifies iterative stakeholder workflows, temporal decomposition, automation, and KPI visualisation as the missing link between mature optimisation research and real planning adoption.
A holarchic approach for multi-scale distributed energy system optimisation
Julien Marquant, Andrew Bollinger, Ralph Evins, Jan Carmeliet | Applied Energy, 2017
Core scaling paper behind city and district optimisation. It connects building-level detail to larger district models and reports 10-100x computational speed improvements with minimal accuracy loss.
Reducing computation time with a rolling horizon approach
Julien Marquant, Ralph Evins, Jan Carmeliet | Procedia Computer Science, 2015
Shows how full-year operating strategy optimisation can be solved faster without relying only on typical-period shortcuts.
Optimising urban energy systems: simultaneous system sizing, operation and district heating network layout
Boran Morvaj, Ralph Evins, Jan Carmeliet | Energy, 2016
Combines technology sizing, hourly operation, and district heating network layout in one optimisation model. The case study found a 23% emissions reduction at the same cost.
Optimization framework for distributed energy systems with integrated electrical grid constraints
Boran Morvaj, Ralph Evins, Jan Carmeliet | Applied Energy, 2016
Adds electrical grid constraints to distributed energy system optimisation, showing that grid-aware design and operation can reduce emissions and defer grid upgrades.
The Ehub Modeling Tool
Andrew Bollinger, Viktor Dorer | Energy Procedia, 2017
Open-source precursor showing how raw district descriptions can be translated into executable optimisation models and interpretable outputs.
Advancing the thermal network representation for optimal design
Danhong Wang, Xiang Li, Julien Marquant, Jan Carmeliet, Kristina Orehounig | Frontiers in Energy Research, 2021
Compares MILP thermal-network approximations with thermal-hydraulic simulation, clarifying where simplified optimisation is reliable and where extra constraints improve design quality.
A call to action for building energy system modelling in the age of decarbonization
Michael Wetter, Matthias Sulzer | Journal of Building Performance Simulation, 2024
Explains why decarbonised, digitalised energy systems require a jump toward more holistic modelling, simulation, and optimisation workflows.
The energy supply security pyramid
Matthias Sulzer, Georgios Mavromatidis, Alejandro Nunez-Jimenez, Michael Wetter | iScience, 2025
Turns energy supply security into a quantitative planning framework, useful for policy, resilience, and infrastructure investment decisions.
Integrated energy solutions for sustainable port development
Elimar Frank, Thomas Franz, Felix Rost, Andrew Bollinger, Laura Jakobeit, Michael Schüller, Martina Heer | ISEC - 4th International Sustainable Energy Conference, 2026
A direct Sympheny application: the Swiss Rhine port of Basel-Kleinhüningen modelled as a multi-hub integrated energy system. Using hourly MILP optimisation, the 2035 concepts cut greenhouse-gas emissions by 82-97% and energy imports by 39-44% at comparable annual cost - published evidence of the platform on a live infrastructure decision.
Decarbonizing the electricity grid: the impact on urban energy systems, distribution grids and district heating potential
Boran Morvaj, Ralph Evins, Jan Carmeliet | Applied Energy, 2017
Links the design of local energy systems to a decarbonising grid above them, using linearised AC power flow and grid-upgrade options. It shows how the cost-optimal mix of district heating and distributed technologies shifts as the surrounding electricity grid gets cleaner - the kind of forward-looking question utilities and cities actually face.
A new combined clustering method to analyse the potential of district heating networks at large-scale
Julien F. Marquant, L. Andrew Bollinger, Ralph Evins, Jan Carmeliet | Energy, 2018
Extends the multi-scale method: a clustering schema that estimates where district heating networks pay off across a whole city, based on building characteristics. It is the bridge between building-level detail and city-scale screening that lets planners find network opportunities without modelling every building by hand.
These 14 are a selection from 20+ peer-reviewed publications in the Empa and ETH Zürich research line. The full source-linked list, with DOIs, is in the technical validation pack.
The science has been applied to real infrastructure decisions
The research proves the method works; the projects show teams can use it under real constraints: multiple owners, networks, tariffs, carbon targets, resilience requirements, and capital decisions.
Joint Base Andrews - Thermal Network, USA
First DoD platform-based design application; thermal network design completed.
Field evidence for defense-grade installation energy planning and resilient thermal-network design, grounded in the same structured design and energy-hub logic described by Sulzer, Wetter, Mutschler, and Sangiovanni-Vincentelli.
Industrial Harbor Energy Community, Basel (IWB)
20-25% energy cost reduction across a multi-stakeholder industrial and utility site.
Closest analog to multi-owner port, industrial, and community energy systems where governance and infrastructure decisions overlap.
Net-Zero Commercial Park, Gossau, Switzerland
75% CO2 reduction and 20% lower lifecycle cost versus reference.
Strong cost-benefit benchmark for low-carbon commercial campus and district planning.
Energy Self-Sufficient Campus, Birr, Switzerland
Full self-sufficiency design using PV, hydrogen, biogas CHP, and batteries.
Validates islanding, seasonal storage, and hydrogen carrier logic in a practical planning workflow.
Nanoverbund, Basel
A community thermal sharing network, live since 2023/24.
Field evidence for installation-community thermal coupling and shared local energy infrastructure.
Zurich Industrial Site Strategic Energy Plan
65% CO2 reduction at lifecycle cost parity.
Demonstrates multi-carrier planning across waste heat, heat pumps, PV, industrial loads, and cost constraints.
GEVAG Waste Incineration Plant, Trimmis (Graubünden)
54–65 CHF/tonne CO2 lifecycle cost. Amine washing optimal under high electricity-price scenarios.
Carbon-capture feasibility study: modelled energy flows (steam at 400 °C / 230 °C, hot water at 120 °C, electricity) and compared amine washing vs. hot potassium cycle. Sub-contracted by Empa. Tags: industrial · CCS · decarbonisation.
Sympheny helps teams make better energy infrastructure decisions because the optimisation method has already been stress-tested.
The commercial claim is simple: more credible scenarios, faster iteration, and clearer investment trade-offs for complex energy systems.
Using Sympheny for a university course or research project? See our academic programme.