ecoRegeneration: Development of a "Merit-Order" in order to assess regeneration heat for geothermal probes within urban residential neighbourhoods

In urban residential areas there are not enough active-cooled usages, to use the waste heat of the cooling process as required regeneration heat for geothermal probes; free cooling of the apartments is not sufficient. The project is developing various options (waste heat from commercial uses in the ground floor zones of residential buildings, by using waste heat of data centres, additional installation of heat generation systems for regeneration) within the urban settlement area, business models and is calculating life-cycle-costs of all solutions. The result should be a kind of "merit order" for regeneration heat.

Short Description

Starting Point

Larger Austrian cities are confronted with the necessity to develop new districts. This process includes the development of new energy supply systems. The objectives in terms of reducing greenhouse gas emissions require an extended use of local, renewable energy resources. Promising heat supply concepts contain the components of heat pumps and borehole heat exchangers for seasonal storage. In urban settlements for apartments heat demand is significantly higher than cooling demand. In this case, a field of borehole heat exchangers must be thermally regenerated, so that the temperature of the soil does not constantly decrease and deteriorate the efficiency of the system. Urban residential areas have too little cooling demand to regenerate the borehole heat exchangers, therefore additional solutions are required. Waste heat is an option which can be used to regenerate borehole heat exchangers.

Contents and Objectives

The aim of the project was the development of a technical and economical basis for regeneration heat in urban residential areas. This included a detailed technical examination, determination of cost data, development of business models and the calculation of the "Merit-Order" for the following solutions of regeneration heat:

  • Use of waste heat of industrial enterprises in the ground floor areas of residential buildings (e.g. supermarket)
  • Use of waste heat resources from data centers right next to urban settlements
  • Technical assessment and economic evaluation of additional heat supply systems, such as hybrid collectors and solar absorbers.
  • Know-how transfer and stakeholder process for the integration of asphalt collectors


The economic viability of possible solutions for the thermal regeneration of borehole heat exchangers was based on different scenarios regarding the size of the buildings and the regeneration possibilities. Based on elaborated technical concepts for thermal regeneration, cost data for the initial investment as well as for operation were determined. With these data and the assumptions of calculation parameters a calculation of economic efficiency according to OeNORM M 7140 was realized. The technical concepts were discussed with stakeholders or used in real feasibility studies and evaluated during the planning process.

Results and Conclusions

Results of the project are application guidelines for the optimal early involvement of cost-effective regeneration heat in the planning and building of urban residential areas. The guideline is directed at municipalities as well as project developers and planners. This information is intended to promote easier implementation of renewable heat supply concepts in urban residential areas.


In addition to the economic aspects, organizational questions will increasingly arise in the future. At present, it is difficult to implement geothermal heat exchanger fields for several buildings with different owners within the framework of a cross-building heating network. In addition to the higher investment costs at the beginning, the installation work must also be carried out at a very early stage, even before the construction work for the buildings begins. This poses a challenge for installers and operators of heating networks to make greater use of these systems. Here, the support of local authorities should help to set requirements for property developers in order to be able to implement these concepts more easily and to appoint a coordinated, independent authority which is able to control the greater coordination effort right from the very beginning of the planning of the urban development area.

Project Partners

Project management

e7 Energie Markt Analyse GmbH

Project or cooperation partners

  • Institute of Building Research & Innovation ZT-GmbH
  • TINA Vienna GmbH (Energy Center)
  • VASKO+PARTNER INGENIEURE Ziviltechniker für Bauwesen und Verfahrenstechnik GesmbH

Contact Address

DI Gerhard Hofer
Walcherstraße 11/43
A-1020 Wien
Tel.: +43 (1) 907 80 26