CarbonZero4IMS

The Inge-Morath residential neighbourhood in Graz is currently supplied with heat by central gas boilers and decentralised gas heating systems. Where central gas boilers are used, domestic hot water is produced locally using electricity. A shared energy supply concept is needed to replace fossil fuels and provide moderate cooling during summer. Connecting the entire neighbourhood to district heating is not economically feasible, while air-source heat pumps have been ruled out due to expected noise emissions. The existing underfloor heating systems favour a heat pump solution.

However, implementation requires clarification of land availability, property rights and permits for the borehole field and PVT system. In addition, five owners’ associations must reach the necessary majorities for decision-making. Key challenges include the cost-effective sizing and long-term regeneration of the borehole heat exchangers, as well as coordinating heat sources, building thermal mass and domestic hot water production with their different response times. Thermal comfort, energy costs and grid constraints must also be taken into account.

Objectives of the CarbonZero4IMS project

The aim of CarbonZero4IMS is to develop and demonstrate a fully renewable heating and cooling system for an existing residential neighbourhood as a transferable alternative to fossil fuel-based energy supply systems. Heat pumps, geothermal boreholes and photovoltaic-thermal (PVT) collectors will be connected via an anergy network and optimised in terms of energy efficiency and cost-effectiveness using a digital twin and predictive control. Key objectives include involving property owners in decision-making, designing a climate-resilient system and optimising its components, implementing the energy supply concept and validating its performance under real operating conditions. The project aims to replace natural gas, reduce CO₂ emissions, improve efficiency and occupant comfort, and lower investment costs through optimised system sizing. In the long term, it seeks to establish a scalable approach to decarbonising existing residential neighbourhoods and developing renewable energy contracting solutions.

Approach and methodology of the CarbonZero4IMS project

StadtLABOR supports property owners in the decision-making process through workshops and surveys. Energie Steiermark clarifies the technical and legal framework conditions and implements the energy supply concept as the energy provider.
Based on heating, cooling and electricity load profiles, AEE INTEC develops a digital twin for the simulation-based design of heat pumps, geothermal boreholes, the PVT system and the anergy network. GREENoneTEC supports the design and integration of the PVT system. The digital twin is combined with dynamic annual simulations and optimisation algorithms to optimise the system configuration, components, storage capacities and borehole layout under technical, economic and climatic constraints. Based on this, load forecasts using machine learning and control strategies that exploit the thermal inertia of the system are developed. Measurement data, weather forecasts, energy prices and individual comfort requirements are incorporated. Evon GmbH integrates the algorithms with the building automation system via XAMControl and a cloud-based data platform. During real-world operation, the models are validated, while efficiency, costs and comfort are evaluated using defined performance indicators.

Demonstration and pilot applications of the CarbonZero4IMS project

The demonstration is planned for the Inge-Morath residential neighbourhood in Graz. Three central heating plants will be connected via an anergy network, with a geothermal borehole field and a PVT system serving as heat sources. The decentralised gas heating systems are to be replaced by individual heat pumps. The demonstration will test heating, moderate space cooling and load shifting through the use of thermal storage capacities in the network and buildings. Predictive control will be integrated with the existing building automation system and tested under real operating conditions. Operational data from buildings and technical systems will be used to assess energy efficiency, control performance and occupant comfort, as well as to validate and continuously refine the models. Implementation will require agreement among the owners’ associations, suitable areas for geothermal boreholes and PVT collectors, business models for providing thermal source energy, and clarification of property rights and permits.

Expected results of the CarbonZero4IMS project

The main expected project results and model solutions include a transferable concept for renewable heating and cooling supply in existing residential neighbourhoods and a digital twin for optimised system design (evaluation of components under technical, economic and climatic constraints) as well as for predictive, self-learning system operation. In addition, MPC, MHE and ML methods will be integrated with real-time data and building automation and validated under real operating conditions.

Benefits and impact of the CarbonZero4IMS project

The project establishes a transferable approach to decarbonising existing gas-supplied residential neighbourhoods, combining renewable heating and cooling with intelligent system operation and cross-sector optimisation. Benefits for the energy system include reduced fossil fuel consumption, grid-supportive use of flexibility and more efficient system sizing and operation. From an economic perspective, operators and residents can benefit from lower energy costs, optimised investments and new contracting and service models. Based on a projected 80 implementations by 2045 and savings of approximately 150 tonnes of CO₂ equivalent per implementation, the potential annual reduction amounts to around 12,000 tonnes of CO₂ equivalent. At the same time, approximately 8,000 households could be reached. Early involvement of property owners and residents strengthens acceptance and feasibility and supports replication in comparable residential neighbourhoods.

This project is funded by the “Leuchttürme der Wärmewende (Flagship Projects for the Heating Transition)” program by the Austrian Climate and Energy Fund with funds from the Federal Ministry for Innovation, Mobility and Infrastructure and is being carried out as part of the Alliance for Green Heating and Cooling Innovation Lab.