Geothermal Tunnel Lining

Geothermal Energy

REHAU are experts in the use of Geothermal Technology to utilise the abundance of Ground-source energy, a renewable and sustainable source of energy that can be used for heating and cooling a variety of different construction projects. Over the past few years, architects, consultants and clients have realised that renewable energy is the future. 

At 1.5m deep, the ground temperature is around 8-12ºC and below 15m deep it is a constant 10ºC. Ground-source energy can be exploited throughout the whole year and provides significant reductions in carbon dioxide emissions and energy costs


Geothermal Tunnel Lining is a great example of REHAU’s ability to apply the benefits of its various intelligent solution concepts and products to enhance an existing engineering application. REHAU has successfully installed its Geothermal Tunnel Lining technology in projects across Europe, ensuring that contractors make the most of both the Geothermal Energy available at such depths and the heat generated by tunnel traffic. 

By using REHAU’s Geothermal Tunnel Lining as part of the tunnel construction, the tunnels themselves generate a source of renewable energy for the surrounding commercial and domestic needs. 

When included at the very first stages of tunnel project development, Geothermal Tunnel Lining is both simple and cost effective.

REHAU’s complete solution has been designed to fit within the existing tunnel fabrication rather than it being an addition to what are already complex, precision projects. REHAU offers complete project solutions that ensure the desired result is achieved economically both in time and cost.

Segment Construction

REHAU RAUWAY pipe assembled to a steel mesh or cage forms a module. These modules are inserted into the segment moulds before concrete is poured. Once a segment has been constructed, it forms part of a ring.

Tunnel Lining Construction

From the tunnel boring machine (TBM) the pre-fabricated concrete segments are installed. Typically 7 segments and a keystone complete a ring. The absorber pipes in each segment are connected at radial and circumferential joints to create a continuous loop using REHAU EVERLOCTM fittings. Robustness and speed of installation is ideal for tunnel construction applications.


Hot Tunnel Applications:

  • Deep/long rail and road tunnels or service tunnels (power, sewer)
  • Tunnel air temperature higher than ground temperature
  • Extracted energy mainly from tunnel
  • Energy used for space heating and hot water demand above ground
  • Significant cooling effect for the tunnel

Cold Tunnel Applications:

  • Short rail and road tunnels
  • Tunnel air temperature similar to ground temperature
  • Extracted energy mainly from soil mass around the tunnel (ground-source application)
  • Provides heating and cooling for buildings above ground

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