ECR Energy City Graz - subproject 3: +ERS - Plus Energy Network Reininghaus Süd

The multifunctional neighbourhood "+ERS - Plus Energy Network Reininghaus Süd" was realized within the urban planning area of Graz-Reininghaus. The project aims to optimize the energy concept of the single buildings as well as of the building cluster in order to achieve a plus-energy standard within the residential neighbourhood.



Short Description

This project is a sub project of the flagship project "ECR Energy City Graz - Reininghaus".


Starting point

The “Plus Energy Network Reininghaus Süd” is an integrative part of the Building of Tomorrow Flag-ship project “Energy City Graz-Reininghaus (ECR), which is an important part of the greater urban development framework of the City of Graz. The side of the “Plus Energy Network Reininghaus Süd” is situated between Gollweg and Grazerfeldstraße on the south joint of the new city development area ECR. In order to find the best concept and exemplary architecture the “WEGRAZ” (a project development association) as owner of the property called for an architectural competition together with the city of Graz. The office “Nussmüller Architekten ZT” won the competitive tender and was appointed as general planner. The new multi-functional neighborhood is split into two parts: the front building complex consists of office- and commercial premises with a supermarket and apartments for elderly people on the first floor. The front building complex forms a row along Peter-Rossegger-Straße and  shelter for the twelve residential multi- family houses behind. The front building complex is realized by “WEGRAZ” in summer 2012. The second building complex consists of 12 houses with 162 flats and is constructed by “Aktiv Klimahaus Süd GmbH” (a real estate) within the research project “Plus Energy Network Reininghaus Süd”. A combination of energy efficiency measures, energy production on side and energy transport to the building complex in front enables a Plus Energy Network.

The plus energy approach of the housing complex is based on synergies within a multifunctional  assembly. In a first step single buildings are optimised, in a second step the residual energy demand is covered by energy production on site and in a last step synergies within the whole building assembly provide further energetic optimisation, turning the housing complex from energy consumer to energy producer.

With the “Plus Energy Network Reininghaus Süd”, a demonstration building project showing that economical, technical and organisational innovative solutions for plus energy concepts  the future are possible, has been realised.

Contents and Objectives

Main objective was the realization of a settlement, achieving a positive energy balance through an innovative bundle of measures.

Contents and objective of the research project are:

  • Optimization of the plus energy assembly of the twelve housing buildings of construction stage BA 02
  • Optimization of the plus energy network by using synergies between the  housing buildings of BA 02 and the office and shopping complex of building part BA 01 in front.
  • Long-term management of the innovative concept and the quality of the demonstration project to reach targets of “Building of Tomorrow”.
  • Verification of targets reached and workmen ship defined by TQ-B (ÖGNB).
  • Monitoring and evaluation of the building performance
  • Providing information for target groups, publication and dissemination, optimized integration in “Building of the Tomorrow” flagship project „Energy City Reininghaus (ECR)“.
  • Preparation of results for follow-up projects and presentation of results on national and international level.
  • Usability of results for follow-up projects.


The project is divided into 7 working packages:

  • WP 1 – Scientific project management, coordination and documentation
  • WP 2 – Optimization of the Plus Energy Concept
  • WP 3 – Quality management, TQ-B audit
  • WP 4 – General planning
  • WP 5 – Construction
  • WP 6 – Monitoring
  • WP 7 - Dissemination


The project ERS demonstrated, that energy networks in the building sector are an important contribution to reach energetic and climate change policy targets. Enlarging the energetic system borders from single buildings to multifunctional building assemblies opens new possibilities for the increase of energy efficiency in the building sector. Due to different use- and load profiles of multifunctional building assemblies numerous energetic synergetic effects, with low investment cost can be generated. The realization of the plus energy network Reininghaus Süd demonstrated that in the near future economical, technical and organizational  for plus energy networks are possible. A successful implementation has to be done  a package of measures like reduction of the heating and cooling energy demand, electricity demand for HVAC systems and households, energy efficient HVAC systems, energy production on site and the energetic network of buildings with different use and load profiles (in the case of ERS office and residential buildings). Technologies installed in the project ERS (geothermal energy, solar thermal plants, PV, balanced ventilation with heat recovery) are well established systems, in general causing marginal problems in implementation. As there are no practicable tools and experiences with the simulation of energy networks, a big challenge turned out to be the planning (simulation) of the energetic network with all components.

Furthermore first monitoring results and the supervision in operation phase showed, that an energetic optimized operation of the energy network requires a competent facility management.

The complexity of energy networks requires special knowledge for operation, control and monitoring of all components. In the project ERS it turned out, that landlords and property managers within their core business have severe problems to install and handle energy . To overcome these hurdles in future an additional purchase of knowledge or the outsourcing of the operation of energy networks to experts should be done. Contracting models are worth to think of.

The project ERS showed, that besides technological challenges for design and operation of energetic building assemblies, especially on organizational and legal level a lot of openended question are remaining. The development of innovative business models and legal conditions will support landlords, property developers, planers and municipalities  implement energy networks in the future.

Prospects / Suggestions for future research

Up till now optimization of energy concepts mainly have been forced within the system border of single buildings. On demand side the passive house standard has reached its technical and economical limit, optimization of this standard (e.g. by increased thermal insulation measures) offers only low potentials for further energy reduction. Furthermore energy supply by energy sources on side (like geothermal and solar energy) from technical and economical point of view often turns out hard to realize. Expanding the system borders from the single object to building assemblies, new possibilities of energy efficiency increase can be found.

Due to their different use and load profile multifunctional building assemblies (consisting of buildings with different use) offer numerous synergy effects. In case of this future energy concepts for the urban area have to focus on the intelligent crosslinking of buildings, building assemblies or city districts.

The construction of the Plus Energy Network Reininghaus Süd created an exemplary role model, demonstrating the economic and technical feasibility of plus energy networks between buildings with different user profiles. Project results on technical, organizational and administrative level provides valuable findings for the design of future energy networks in the building sector.

Large interest on national and international level for the results of the ERS project, shows the actuality of the topics dealt with. The experiences with the “ ERS” and the “Energy City Graz-Reininghaus” projects have served as catalyzers for seeking paramount objectives in the city. Currently, Graz is focusing on becoming a “Smart City”, with a detailed summary of objectives and measures included in its plan “I live Graz” and the resulting project “Smart Project Graz”. These plans started with the high objectives in energy matter of “Energy City Graz-Reininghaus” and ERS, developing from there to include many other aspects, such as mobility, ecology, and society. The knowledge gained from this project regarding energy networks between buildings will be used in further research projects.

On technical side future research activities should focus on adequate, practicable tools to calculate energy networks of settlements within the whole design process (preliminary design to implementation planning). Aim should be a continuous tool for all planning stages, getting more and more precise with the progress of the planning process. Furthermore the integration of monitoring results to optimize the running energy network has to be forced.

As a project like +ECR involves a significant number of actors (different landlords, energy service companies, properties management, etc.) an amount of confidence and mutual trust is needed for the successful completion of the project. As there is a lot of unclarity concerning legal issues (e.g. design of energy service contracts, responsibilities for the control of the network, energy bills) clarification of the legal framework is an important task.


Project Partners

Project management

Aktiv Klimahaus GmbH

Project coordination

AEE Institut für Nachhaltige Technologien (AEE INTEC)

Project and cooperation partners

Nussmüller Architekten ZT GmbH

Contact Address

Aktiv Klimahaus GmbH
8282 Ilz 92