Mibec are pleased to supply AWADUKT Thermo from REHAU. This solution is a ground-air heat exchanger system, also known as earth tubes, for pre-tempering ventilation air. The ventilation air is drawn through underground pipes buried at a depth of 1.5m, which pre-cools the air in the summer and pre-heats it in winter, using the near constant temperature of the ground (7-13°C). Experience has shown it is possible for a system to cool the air by 14°C in the summer and heat it by 9°C in the winter.

The system has been extensively used across the UK in commercial projects, mainly in the education sector. The system is ideally linked up with a mechanical ventilation unit with heat recovery (MVHR) to offer a full ventilation solution.


  • The ground’s ability to store energy is used to achieve an energy-efficient controlled ventilation solution
  • Low energy cooling system for buildings built to zero carbon / PassivHaus standards
  • Antimicrobial silver inner layer to prevent microbial growth inside the pipes
  • Thermally-optimised polypropylene material for improved heat transfer
  • Design software available to estimate energy savings for a project
  • Complete system available from air inlet tower to condensation chambers and wall seals
  • Solutions suitable for both residential and commercial applications

Domestic applications

The system requires a minimum of 40m of pipe for the optimum performance. This can be laid in a ring pattern around the house, a meander pattern or in a straight line away from the building.

REHAU have created 4 different domestic packages for different size properties, which include all key components such as pipe, fittings, condensation chamber, wall inlets and air inlet tower.



Commercial applications

For a commercial project, a Tichelmann grid is used. This is a self-balancing system to ensure the air can only travel the same distance through each heat transfer pipe. The heat transfer pipe is typically DN200-250 diameter. The system size is based on 3m/s maximum velocity through the heat transfer pipes. Tichelmann grid systems are often installed under grass areas or car parks, but in some cases, can alternatively be installed under buildings.


At Mibec we offer a full free of charge specification service covering the whole of the UK, designed to support architects, specifiers or contractors. We can give you knowledgeable, yet impartial advice on selecting the right solutions to meet your projects needs. Please feel free to email or call our support department on 01782 959170 (local call rate) where one of our trained advisers will be more than happy to help you.