Research-backed optimisation

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.

20+
peer-reviewed publications
10+ yrs
Empa / ETH research lineage
5+
energy carriers in one model
Concrete claims

What the research shows

Structured
design workflow

Platform-based design gives complex energy systems a structured design workflow, inspired by advanced engineering industries, to manage complexity and reduce project risk.

Sulzer et al., Applied Energy 2023
Public
Zurich district dataset

The platform-based design paper includes a public Modelica/Sympheny district dataset, giving technical reviewers a concrete reference implementation instead of only a conceptual framework.

LBNL Simulation Research Group GitHub dataset
10-100x
faster at city scale

Solving a whole city as one optimisation model quickly becomes intractable. Published multi-scale and rolling-horizon methods cut that solve time by 10 to 100 times while staying within about 1% of the optimal result.

Marquant et al., Applied Energy 2017; Procedia Computer Science 2015
40%
more renewables without grid upgrades

Grid-aware distributed energy optimisation can integrate substantially more renewables by coordinating system design and operation with electrical constraints.

Morvaj et al., Applied Energy 2016
18%
emissions reduction in operation

Including electrical grid constraints in operating schedules reduced emissions in the published test case while controlling voltage and current variation.

Morvaj et al., Applied Energy 2016
23%
lower emissions at same cost

A simultaneous MILP model for technology sizing, operation, and district-heating layout showed district heating could reduce emissions without increasing system cost in the case study.

Morvaj et al., Energy 2016
Open source
tool lineage

The Ehub Modeling Tool translated raw district data into executable optimisation code, establishing the software pattern behind today's product workflow.

Bollinger and Dorer, Energy Procedia 2017
5 tiers
security framework

Energy supply security can be quantified as a planning objective, helping teams evaluate resilience instead of treating it as a qualitative afterthought.

Sulzer et al., iScience 2025
4 cases
research-practice bridge

Applied case-study work showed that iterative stakeholder workflows, temporal decomposition, automation, and clear KPI visualisation are critical to bringing optimisation into real planning practice.

Bollinger, Marquant and Sulzer, IOP Conference Series 2019
Technical validation pack

Need to share the technical basis internally?

Download a concise source-linked pack with the key claims, research summaries, DOI links, open datasets, and access notes behind Sympheny's optimisation engine.

Download validation pack
Key research

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

multi-energy systems modelling review optimisation

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

structured design energy hub digital workflow

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

practice gap automation KPI workflow

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

MILP clustering multi-scale

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

rolling horizon energy hub solve time

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

district heating network layout CO2/cost

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

grid constraints renewables distributed energy

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

software automation energy hub

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

thermal networks model validation MILP

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

decarbonization workflow modelling

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

energy security resilience policy

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

port development sector coupling applied case

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

grid decarbonization district heating distribution grid

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

clustering district heating city scale

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 short version

This is not a static calculator.

Sympheny is not a reporting layer on top of spreadsheets. It is an optimisation workflow for multi-carrier energy systems, built around published methods for modelling networks, technologies, storage, and hourly operation in one decision process.

Multi-energy optimisation

Sympheny is built on the energy-hub formulation: electricity, heat, cooling, gas, hydrogen, storage, and conversion technologies are modelled together instead of as disconnected calculations.

So the platform can size technologies, schedule operation, and compare cost, CO2 and self-sufficiency on one consistent model.

Network-aware planning

The research does not stop at choosing equipment. It includes district heating layout, thermal network losses, grid constraints, and interactions between buildings.

That's what makes Sympheny work for districts, ports, campuses, utilities, and multi-owner energy communities.

Computational scaling

Peer-reviewed clustering and rolling-horizon methods reduce the computational burden of full-year, multi-building optimisation.

Planners can evaluate many more scenarios in the same project window, instead of shrinking the problem until it fits a spreadsheet.

Decision-grade evidence

The same research line has been applied in real energy concepts, city-wide roadmaps, industrial sites, campuses, and policy-adjacent modelling.

It's what turns the science into practical planning evidence: lower risk before capital is committed, clearer trade-offs, and more confidence in the investment.

From research to field evidence

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.

DoD ICES

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 ICES

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.

Commercial ICES

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.

Campus microgrid

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.

Heat network

Nanoverbund, Basel

A community thermal sharing network, live since 2023/24.

Field evidence for installation-community thermal coupling and shared local energy infrastructure.

Industrial ICES

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.

Industrial CCS

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.

Why it matters

Proof that supports technical and investment decisions

Technical confidence

Trust the model structure: the underlying methods are published and peer-reviewed, not hidden spreadsheet logic.

Model the real system: technologies, carriers, networks, storage, and hourly operation interact in one optimisation.

Explore more options: clustering and rolling-horizon methods make larger scenario sets practical.

Defend the recommendation: every scenario can be compared on cost, CO2, self-sufficiency, and network impact.

Investment confidence

Reduce investment risk before committing capital to infrastructure that will last decades.

Quantify trade-offs rather than picking a single vendor-led concept too early.

Find designs that improve carbon and cost together when the system allows it.

Give internal champions evidence they can take to budget holders, boards, and public stakeholders.

Bottom line

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.

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