Sewage is an overlooked energy source, though, it carries away approximately 15% of the thermal energy provided to a conventional building and flows in cities where demand for heating and cooling is high. We recognize this at Thermowatt and have developed a unique solution that allows a heat pump to recycle this thermal energy even from raw sewage and use it to provide heating and cooling services in densely populated city centers. Our installations currently serve a hospital, conventional center, market hall, university and municipal and administrative buildings with a combined area of more than 110,000 square meters.