Johnson Controls will supply ammonia-based heat pumps to the city of Zürich as part of a waste heat recovery project led by municipal utility ERZ (Entsorgung & Recycling Zürich). The installation is scheduled to begin operations in 2027 and will contribute to Zürich’s district heating network, providing additional heat to approximately 15,000 homes.
The project involves the expansion of a waste-to-energy facility with a third process line and recovery of heat from flue gases. Johnson Controls will deliver a customized heat pump solution comprising six high-performance screw compressors with a total system output of 42 MW. The units will extract low-temperature heat from the flue gases and return it to the district heating grid.
To optimize energy efficiency, the heat pumps will be configured as three pairs operating in series, minimizing the temperature lift required. This design is expected to improve system efficiency by up to 30%. The heat pumps will be the first in a chain of multiple heat sources, ensuring optimal thermal conditions for the overall process.
This installation is among the largest in Europe to use ammonia—a refrigerant with zero Global Warming Potential (GWP)—in a heat pump application of this scale.
“The City of Zürich is actively committed to achieve net carbon neutrality by 2040 and a major part of this is the increase of carbon free supply of heat. By teaming up with Johnson Controls, we’re further driving momentum in the heat transition and paving the way toward a more sustainable future,” said Jürg Bruder, ERZ.
