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Energy from wastewater
Use wastewater heat for heating, cooling and hot water!

Energy from wastewater for heating and cooling buildings!

Technologies for using energy from wastewater are economical, efficient and innovative solutions - absolutely in tune with the times! Over 50% of the world's energy requirements are used for heating and cooling, including hot water preparation. With wastewater heat, we have a huge energy potential at our disposal, which can be used for this purpose using state-of-the-art heat exchanger and heat pump technology. As part of our membership of act4.energy and the Thermaflex Green Energy Lab as well as well-known associations and networks, we develop innovative solutions for industry, commerce and local authorities.

Sewer waste heat heats and cools buildings

If office and residential buildings, hospitals or shopping centers are located near sewers with a wastewater flow rate of at least 10 liters per second, these buildings can be heated and cooled in a particularly economical and environmentally friendly way using energy from the wastewater. Innovative heat exchanger systems and efficient heat pumps are used here, which significantly reduce energy costs andCO2 emissions for systems with an output of 100 kW or more.

With our proven technologies, we provide you with a solution that meets your requirements:

Channel heat exchanger with dry weather channel

  • Suitable for all duct shapes, quick installation
  • Optimum heat utilization, as the entire surface is overflowed even in dry weather
  • Flow and return pipes are laid underneath the heat exchanger to ensure easy maintenance of the duct by the operator

External heat exchanger

  • For large projects from approx. 500 kW output
  • Waste water is pumped out of the sewer via a shaft and pre-cleaned using a mechanical filter
  • Extremely high efficiency levels (COP 7 to 8) can be achieved using externally mounted heat exchanger bundles and heat pumps

Further information on the use of energy from wastewater for heating and cooling buildings can be found here.

Building technology of the future - with hot water preparation

Every day, a considerable amount of wastewater is produced in buildings. With innovative, self-cleaning heat exchangers, it is possible to recover up to two thirds of the heat from the wastewater and use it efficiently to heat water. The result: lower energy consumption, lower costs, lowerCO2 emissions.

Rabmer supplies innovative heat exchanger systems for this purpose:

Heat tower - static system

  • The waste water is collected in the shell of the tower and heats the fresh water in the inner tank.
  • The heated water is taken from the upper part of the inner tank and fed to the existing hot water preparation system as preheated fresh water.

Plate heat exchanger - continuous flow system

  • The pre-cleaned waste water flows through the counterflow heat exchanger and heats the incoming fresh water.
  • A cleaning scraper removes dirt from the heat exchanger surface every day, ensuring optimum heat transfer.

Basic requirements

  • Waste water volume: at least 2m3 per day
  • Residential buildings: Greywater pipe separate from faecal wastewater; central water heating available
  • Spatial proximity of the waste water pipe to the central water heating system


  • Swimming pools, sports facilities
  • Hotel industry, wellness parks
  • Commercial kitchens, hospitals
  • Food processing industry
  • Laundries
  • Residential complexes
  • Retirement homes
  • and much more ...


As part of our membership of act4.energy and the Thermaflex Green Energy Lab, as well as well-known associations and networks, we develop innovative solutions for industry, commerce and local authorities.

Our services for you:

  • We look for the best technology for your project.
  • We carry out a feasibility analysis for you and calculate the cost-effectiveness.
  • We take care of the implementation including delivery and installation with our partners.
  • If required, we can also take over the maintenance and operation of the system.

We are happy to advise you

Please contact us:

Dr. Rainer Wiedemann
Head of Energy from Wastewater
+43 664 88 30 90 43