The Stift Heiligenkreuz abbey is a beautiful and living Cistercian monastery. It is located in the middle of the “Wienerwald” (the Vienna woods) and serves as the the oldest active and inhabited Cisterian monastery in the world, now full of young vocations. St. Leopold III from the House of Babenberg founded it in 1133, so it has quite a history. That also goes for its district heating network, which was smartly refitted with Flexalen for the local community, using biomass energy from the local sawmill, based on woodchips. This was one of the first projects where Flexalen could prove its worth and propriety for these solutions.
Over 30 years of reliable performance for Heiligenkreuz
Heiligenkreuz, Austria
Flexalen pipes
3 years
75 customers satisfied
3,600 m of Flexalen pipes more than 30 years successfully in service
0 € network maintenance costs and up to 10,000 m³ of re-used bark and sawing wastes
One of the first Flexalen projects in Austria
Goals
The objective was to replace the oil boiler in the diocese, and use bark and sawmill biowastes in a biomass installation for the local heat supply. The use of clean, sustainable energy for the heat supply for the Heiligenkreuz village was the focus, but there was also a desire to achieve an improvement in the air quality.
Main challenges:
- Installation of main line, 3 m deep and near the stream bed,
- High groundwater table,
- Highway crossing,
- Connection of single-family houses with minimal damage to the gardens,
- Overall planning and selection of pumps, home stations, etc.
Project Process
The first construction phase in 1983 saw the installation of the main line from the sawmill to the Abbey Heiligenkreuz. The connections were done using butt-welding by trained welders. The Forestry Commission organized the drainage.
In 1984 the connection of the community buildings (including the town hall, fire department, kindergarten, etc) was realized. One year later, single family houses could be connected to the district heating network too, securing reliable and affordable heat for all connected users.
Results
75 clients including residences, a school, and a kindergarten were connected from the network. Due the flexibility and easy weldability of the material, this could be realized with minimal disturbance to the existing environment and its users. The network’s total length is 3.6 km with heat losses of less than 1°C of the main temperature. The boiler power is 3 Mw + 0.8 Mw biomass, and the nominal power is 2.2 Mw for heating and 2 Mw for wood drying. For the heat supply, up to 10.000 m³ of bark and sawing waste is used. So far, there have been no network maintenance costs, despite the high ground water table. That’s because Flexalen is sustainably resistant to water and mechanical damage, and corrosion-free.
Additional Info
Organisations:
Forstverwaltung Heiligenkreuz (forest management)
Stift Heiligenkreuz (Abbey Heiligenkreuz)
