The heating and cooling requirements of properties in Zurich’s city centre are enormous. In the increasingly hot summer months, air conditioning systems will be used more and more frequently in the future. Our potential analysis revealed a demand of 100.5 GWh of heating and 34.6 GWh of cooling. This makes CoolCity one of the largest lake heat networks in Switzerland. To provide this energy in an environmentally and climate-friendly manner, we developed this long-term project.
The heart of an energy network is the energy centre. Due to the size and energy volumes, CoolCity requires spaces offering 4,000 m² and a room height of 5 metres. After an intensive analysis, existing ewz substation in Selnau was determined as the location. The substation offers outstanding architectural conditions and an ideal location for the future distribution of heating and cooling.
The perimeter covers the area between the main station and Bürkliplatz as well as between Lindenhof and Schanzengraben. The aim is to cover the high heating and cooling requirements of the numerous office and retail spaces with a connected grid fed with renewable energy from Lake Zurich.
The supply temperatures on the customer side are approx. 67 °C (district heating) and approx. 12 °C (district cooling). In the City Anergy supply area, we supply the properties with energy directly from the lake water intermediate circuit (operating temperatures -1 °C to 17 °C). Heat pumps or cooling machines are necessary to bring temperatures to the required level.
Functioning of a lake heat network
Buildings that are connected to a network are supplied with heating and cooling via lines from the central system or have their own heating system. The lake water is collected with a sieve and transported to the central lake water system using pumps. In winter, we use a heat exchanger to extract heat from the water circulating in a primary circuit. This heat serves as an energy source for the heat pump. This raises the carrier medium to the required temperature level (approximately 40 to 65°C). Distribution in the buildings takes place via a secondary circuit. In summer, the system works in reverse: ‘free cooling’ allows the lake water to be used directly for room cooling instead of electricity-powered air-conditioning systems, ensuring comfortable temperatures. At the end, the lake water removed is returned to the lake or the Limmat river without any chemical changes, and the cycle begins over again.
Where and when can a connection be made?
All properties within the network area can be connected to the network. Building-specific information about the energy network can be found here (in German).
Connection is voluntary and gives you the advantage of heating your property sustainably and using local energy, thus already meeting the requirements of future energy legislation.
Your property will be connected to the district heating pipeline for heating and cooling. This primary circuit feeds the energy into your building, where it is prepared for use in the building in the transfer station. ewz takes care of all the work for you up to and including the transfer station. From there, the energy is in your hands. You are responsible for the further use/supply to the property.
Subsidies for collaborative projects
If you switch your heating to a district heating connection, you can apply for subsidies. The application must be submitted no more than two years before the measures are taken and must be submitted before the conversion of the in-house heating system. You can find further information and submit an application here (in German).
If Switzerland wants to meet its climate targets in the coming years, there is no alternative but to focus even more on renewable energy for heating and cooling. Innovative lake heat networks will play an increasingly important role in supplying towns, cities and municipalities close to water.
Energy supply
By connecting to an energy network, you benefit from environmentally friendly heating and cooling produced from renewable energy and no longer need to worry about procuring and operating heating and air conditioning.
Preparing for the connection
We lay a supply line into your property/properties for a one-off fee and with no further obligation. Our energy supply does not begin until the time of your choosing. For example, if you need a replacement heating system.
Temporary solution
If properties require a replacement heating system before being connected, we offer an interim solution starting from a connected load of 100 kW.
- Planning, implementation, financing
- Heating and cooling solution with lake water as a sustainable energy source
- Operation of the energy systems
- 100.5 GWh of heat required per year
- 34.6 GWh of cooling required per year
- 22,700 tonnes of CO₂ saved per year
- 100% carbon-free
No risk for you: We take on the investments and bear financial and technical responsibility. You pay only for the volume of energy purchased and the output power. The costs of planning, construction and operation are borne by us.
The supply to your property/properties is monitored around the clock. Any faults are taken care of at no further cost to you.
Together with us, you will contribute to the sustainable development of lakeside Zurich and bring the city one huge step closer to achieving its 2000-watt goals. By connecting your property/properties, you are investing in climate protection and are now already meeting future energy policy requirements.
