Basically, energy can be obtained from wastewater at three points. Firstly, “in-house”, secondly from the public sewer network and thirdly at sewage treatment plants. With the UHRIG Therm-Liner, we extract energy mostly from the public sewer network, as the volumes of energy are large here and there are many possible energy users nearby. The quantities of energy that can be recovered in an individual building from the wastewater are very small and so extraction would generally be uneconomical. The quantities of energy at sewage treatment plants are very large but after they have been extracted, they need to be taken to potential users. The concept of recovering energy from the sewer network is therefore a decentralised approach that aims to bring source and users together directly. This is the approach we pursue.