Next Target: Net Zero Emissions

Buildings account for around a quarter of Switzerland's CO₂ emissions. If we want to achieve the 1.5° C target of the Paris Climate Agreement, these emissions must be drastically reduced. The institutions of the ETH Domain are all too aware of this. That's why they are researching modern energy concepts – and putting them into practice right away. At ETH Zurich, for example.

Here, 14 buildings on the Hönggerberg are already connected to the "anergy network," and seven more are to follow in the next two years. "Anergy heats and cools at a low temperature level," explains Wolfgang Seifert, energy officer at ETH Zurich, "it sounds unusual, but it's not rocket science." In winter, the heat is extracted from the ground 200 metres deep at 18 degrees Celsius. Heat pumps then raise the temperature to about 34 degrees. "That's what we use for heating. For that to work, of course, you need highly efficient plants and specially designed buildings." At Hönggerberg, anergy supply is standard for new buildings; old buildings are being renovated so that they can also be connected to the anergy network.

One example is the Physikturm, which is now Minergie-certified. "In winter, we heat with energy that we get for free right out of the ground; in summer, we channel excess heat into the ground to cool the buildings." In 2006, ETH Zurich set a goal to reduce CO₂ emissions from its buildings by 50 % by 2020. Seifert and his team have more than achieved this goal, receiving the Watt d'Or energy award for their efforts. "Currently, we are planning how to get to net zero as quickly as possible."

Waste heat storage in the ground

At ETH’s sister institution in Lausanne, the heat supply has also undergone major changes. EPFL's new heating plant, completed in 2021, has more powerful heat pumps than its predecessors, the facades and roof of the new building are completely covered with solar panels, and it is additionally able to use waste heat from the computer center housed in the same building. Already since 1986, heating and cooling have been largely based on water from Lake Geneva. "We take it at a constant temperature of seven degrees and heat it to about 50 degrees with the help of the heat pumps. This is how we operate the joint EPFL and University of Lausanne pumping station," explains Energy Project Manager David Gremaud. And his colleague Gianluca Paglia adds: "Soon we will  be using the waste heat from the servers. To do so, water will be fed through the specially designed doors of the computer racks. This will cool the servers and heat the water." In addition, a pilot area for scientific experiments is planned in one part of the building. This means, EPFL no longer relies on fossil fuels to heat and cool the buildings – and more projects are already planned for the future. "We still have about 15,000 m² of roof space available on which we can install photovoltaic systems," Gremaud explains. "This project is an integral part of EPFL's energy strategy to reduce CO₂ emissions."

Empa and Eawag are located on a joint campus in Dübendorf. A new building complex is currently under construction there, with a high-temperature ground probe storage tank below. The geothermal probes reach down to a depth of 100 metres. Over the next few years, the researchers will investigate how this system directly under their feet, which is used to heat the entire campus, can be further improved. "We use waste heat from refrigeration systems and research equipment," says Hannes Pichler, Head of Real Estate at Empa (which also manages the real estate of Eawag and WSL). "In summer, we conduct this waste heat via the probes directly into the ground  and thus 'charge' the 'battery' for the winter."

In addition, Empa and Eawag also operate a biogas cogeneration plant and produce electricity with photovoltaic systems. The data from the various plants are being analysed in detail. With the help of digitisation, they are to be further optimised in the coming years. "There is still a lot of potential to further increase efficiency," says Pichler, "our next target is net zero. We would like to achieve this as quickly as possible."

More knowledge per energy used

"Of course, we additionally have photovoltaic systems, charging stations for e-cars, we motivate our employees to come by public transport and we are connected to a district heating network that is powered by waste heat," explains Marcel Hofer, energy officer at the Paul Scherrer Institute. "However, our biggest challenge is not the heating systems or mobility at all, but our energy-intensive large-scale research facilities. We need very power-intensive amplifiers to accelerate parts, strong electromagnets to steer and bundle protons and electrons, or cryogenic liquefied helium to adjust the speed of neutrons. Today, we obtain 100 % of the energy for this from hydropower. And the waste heat we generate from our facilities covers more than half of our heating needs. Where we still see the highest potential, is in increasing efficiency. For example, we are currently working on increasing the electron beam brilliance of our Swiss Synchrotron Light Source (SLS) by a factor of 40. This means that we will then be able to perform tomographies a hundred times faster – at an about 20 % lower energy consumption. So, more knowledge per energy used, that's our goal."

The WSL Research Institute for Forests, Snow and Landscape is also present at several locations. "In Birmensdorf, we recently renovated two buildings from the 1950s," says Andreas Zurlinden, Environmental and Safety Officer. "Now the buildings meet the Minergie-A and P Eco standards, and the old oil heating only runs a few days a year when the chimney sweep services the woodchip heating system. At the Davos site, on the other hand, we have installed a heat pump that extracts heat from the groundwater. All in all, this makes us CO₂-neutral, so to speak, in terms of heating."

A new replacement building is currently being constructed in Davos – to SNBS Platinum standard. This goes far beyond the better-known Minergie label. "Minergie is about insulation and energy, SNBS also includes the construction process, the materials used, the quality of the workplaces for employees, the connection to public transport and much more." For a recent report, Zurlinden brought in an author who regularly writes environmental reports for companies. "She had tremendous pleasure because she was finally able to write for an institution that didn't just want a report in which they looked good, but actually lived the values of the environmental report."