Heat pump project to supply 15,000 Zürich homes with waste heat

3 September 2025

Zürich will begin using waste heat from a major incineration plant to provide low-carbon heating to thousands of homes, under a project involving Johnson Controls and the city’s municipal utility.

The scheme will see a new large-scale ammonia heat pump system installed at the city’s waste-to-energy facility, operated by Entsorgung & Recycling Zürich (ERZ). The technology is expected to come online in 2027 and will deliver heat to around 15,000 households through the district heating network.

Johnson Controls will supply the equipment. The company is designing a custom-built solution featuring six high-performance screw compressors, capable of producing a combined 42 megawatts of heat output. The pumps will draw low-temperature energy from flue gases and recycle it into the city’s heating grid. By pairing the units in series, the amount of energy needed to boost the heat to usable levels will be reduced, with efficiency improvements of up to 30% anticipated.

Waste-to-energy plants are already a major part of urban energy systems across Europe, but much of the residual heat from their operations has historically gone unused. Industry bodies say capturing this heat represents one of the largest untapped opportunities to reduce emissions from buildings, which remain the single biggest source of energy demand. The European Heat Pump Association has suggested that wasted heat across the EU could, in theory, provide all the bloc’s needs for central heating and hot water.

Officials in Zürich said the project will make an important contribution to the city’s climate strategy, which commits to reaching net zero emissions by 2040. By replacing gas-fired heating with recovered energy, they argue the system will not only lower carbon output but also make the city less dependent on fossil fuel imports.

“As one of the largest untapped sources of energy, excess heat represents huge potential for businesses to reduce operating costs and become more resilient while meeting decarbonisation targets,” says Richard Lek, Johnson Controls president, EMEA. “In 2024 alone, Johnson Controls helped cut customers’ expenses by 53% and reduce emissions by 60% compared to conventional natural gas boilers. We are proud to be partnering with ERZ on this innovative project and highlight the tremendous opportunity of waste heat sources – paving the way toward more energy-efficient and sustainable urban environments.”

Johnson Controls has previously worked on district heating projects in Germany, including with Hamburg Energy and Stadtwerke Rosenheim. It said the Zürich installation is one of the largest in Europe to employ ammonia, a refrigerant with zero global warming potential, in a heat pump application of this scale.

The project is expected to serve as a model for other municipalities seeking to expand renewable heating networks and integrate waste heat into their energy mix.