Motivation and research question

Many small and medium-sized municipalities face the task of decarbonising their building stock and adapting their public spaces to the consequences of climate change, yet they have only limited personnel and financial resources to do so. The exploratory project MaDoKli investigated how previously unused local water resources in the town of Mannersdorf am Leithagebirge can be made usable simultaneously for the heat supply of municipal buildings, for the careful use of drinking water, and for the climate-responsive design of the town centre.

Initial situation and status quo

Mannersdorf am Leithagebirge has two thermal springs, the Kapellenquelle and the Badquelle, which feed the stream known locally as the Warmbach. In the town centre this stream is largely culverted and only surfaces outside the centre. At the start of the project the municipal buildings were heated predominantly with fossil fuels, the secondary school with heating oil and further buildings with natural gas. The entire municipal water demand, including low-grade uses such as irrigation or street cleaning, was met from the drinking water network. The culverted Warmbach at the square known as the 22er Platz remained unused as a design-related and microclimatic asset.

Project contents and objectives

The project created the foundations for a subsequent implementation undertaking. Three interconnected fields of action were examined: the thermal use of spring and stream water for heating municipal buildings; a use-oriented water management approach that reserves high-quality drinking water for human use and meets low-grade uses from alternative resources; and the reopening of a culverted stream section at the 22er Platz as blue-green infrastructure. The aim was to activate local renewable resources, to gradually free the municipal heat supply from fossil fuels, and at the same time to create a climate-resilient public space with a high quality of stay.

Methodical procedure

The work was carried out in several thematic work packages. The available heat sources and the potential heat consumers were surveyed and consolidated in a building matrix created within the project, which served as the common basis for calculation. A monitoring campaign from July 2025 to February 2026 recorded the temperature regime, water level and flow velocity of the Warmbach using a network of around 21 sensors over a flow distance of approximately seven kilometres. Pumping tests at the Kapellenquelle served to assess the extraction capacity and the effects of withdrawal on neighbouring water rights. In addition, the alternative water resources were assessed quantitatively and qualitatively, technical supply variants were developed, the CO₂ reduction potential was estimated, and several design variants including preliminary dimensioning and a rough cost estimate were prepared for the stream opening. The concepts were reflected upon in guided interviews with key municipal stakeholders and in deliberations of the town council and the municipal council.

Results and conclusions

The investigations confirm the technical feasibility of the thermal use of the springs. The water temperatures of the two springs remained almost constant over the entire measurement period at around 22.8 and 22.6 degrees Celsius respectively, providing the precondition for year-round reliable use. The secondary school has a heating load of around 350 kilowatts, against which an extraction capacity of around 300 kilowatts can be obtained from the Kapellenquelle; combined with a heat pump with a coefficient of performance of 4, this yields a heating output of around 390 kilowatts, which can cover the demand. A full conversion of five municipal buildings results in a savings potential of around 344 tonnes of CO₂ equivalent per year, corresponding to a reduction of about 90 percent compared with the fossil-fuelled stock. As a first binding step, the heating conversion of the secondary school was decided and submitted for water-law approval; with a projected saving of around 113 tonnes of CO₂ equivalent per year, it constitutes the first expansion stage.

From a quantitative perspective, the spring and stream water is by far the most significant alternative water resource and is sufficient to cover the municipal service-water uses.
For the stream opening at the 22er Platz, design variants of differing flow lengths were developed with a rough cost estimate in the range of about 350,000 to 500,000 euros.

The central transferable insight of the project, however, lies less in the technical than in the organisational sphere: the main obstacles are the strongly person-bound and insuffi-ciently documented practical knowledge, overlapping responsibilities between the town municipality and the school municipality, and the strained municipal budget situation.

Outlook

The results were presented to the municipal bodies as a basis for decision-making and were translated into a concrete implementation scenario. The heating conversion of the secondary school is already being implemented; for the climate-responsive redesign of the 22er Platz a feasibility study is being commissioned, on the basis of which funding advice will follow. The project gives rise to further research needs, in particular regarding the framework conditions for implementations within the municipalities' own sphere of action and the interplay between thermal use and the summer cooling function of an open stream, which can be mutually opposed. With the implementation already initiated, an illustrative example with a role-model effect for comparable rural municipalities in the region is emerging.

Project management

Institute of Building Research & Innovation

Project or cooperation partners

• Universität für Bodenkultur Wien, Institut für Ingenieursbiologie und Landschaftsbau
• Regionalentwicklungsverein Römerland Carnuntum
• Stadtgemeinde Mannersdorf am Leithagebirge
• Universität für Bodenkultur Wien, Institut für Ingenieursbiologie und Landschaftsbau
• Regionalentwicklungsverein Römerland Carnuntum
• Stadtgemeinde Mannersdorf am Leithagebirge
• KLAR! Am Leithaberge (cooperation partner)
• Amt der Niederösterreichischen Landesregierung Gruppe Wasser Abteilung Wasserbau (cooperation partner)

Institute of Building Research & Innovation
Philipp Stern
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A-1010 Vienna
Tel.: +43 (1) 5811 319 810
E-mail: office@building-research.at
Web: building-research.at