Homes and offices exchange heat and coolth in smart energy system
Local energy systems where different buildings can share their energy surplus make up an important part of the smart and efficient energy systems of the future. Such a system has already been demonstrated on the campus of Chalmers University of Technology in Gothenburg. Now the local system has expanded and connected a nearby apartment complex to an office building on campus to exchange heat and coolth.
Housing Association Brf Viva was inaugurated in 2019 with the ambition to become Sweden's most innovative and sustainable housing project, based on Riksbyggen's interdisciplinary collaboration platform Positive Footprint Housing. The new energy exchange system, connected to Chalmersfastigheter's property Chalmers Teknikpark, is one of several components that aim to create a flexible energy system with smart management control. For example, used batteries from electric buses that store energy from solar cells on the roofs have also been installed.
“The cooling connection will mean that Brf Viva's geothermal heating facility runs more efficiently and thus draws less electricity. The conditions are special here in that Brf Viva is so close to an office building, which has a greater need for cooling, especially in summer, says Matilda Kjellander,” project manager for Brf Viva at Riksbyggen.
In practice, the energy exchange system means that pipes are laid between the housing association's boreholes and Chalmers Teknikpark, which is located about 200 meters away. Teknikparken's cooling system can fetch cold water from the boreholes, which saves the building's own heat pumps. When this water circulates in the building, to cool the indoor temperature, it in turn absorbs heat and the water temperature rises a few degrees before it is sent back up to Viva's borehole.
It is enough that the water from Teknikparken keeps 10-15 ° C to heat the boreholes and deliver warm water to the radiators and faucets of the apartments, while sparing the system's heat pumps. In other words, the excess heat from the offices is transferred to Brf Viva and recharges the boreholes instead of being lost in an energy-intensive cooling system. Both buildings save electricity as their heat pumps need to work less to heat and cool water.
“For us at Chalmersfastigheter, it is interesting to see how this will work and how much heat and coolth you can transfer between the houses. If we get a lot of coolth, we don’t need to run our heat pumps. Connecting Brf Viva to the campus area, also contributes to expanding the existing test bed operations for innovative energy solutions, that we hope will eventually be scaled up and implemented in other areas,” says Bengt Bergsten, energy strategist at Chalmersfastigheter.
This type of collaborations between different property owners, in this case Chalmersfastigheter and Housing Association Viva, are still unusual, but they are increasingly being presented as an important part of a more energy-efficient society. By taking advantage of the different needs of heating and cooling of two nearby buildings, synergetic relationships can be established between them, so that they meet their needs without straining the city-wide network.
“If this solution works as we believe it will, it could reduce the office building's cooling needs and increase the efficiency of the residential building's geothermal system, and thus reduce both the amount of purchased district heating and electricity from each network, but above all reduce the peak power requirements, which is where the greatest climate benefit lies,” says Peter Selberg from Johanneberg Science Park, who coordinates the project within the framework of the EU collaboration IRIS Smart Cities.
IRIS Smart Cities
The energy exchange system has been financed by the EU project IRIS Smart Cities with the ambition that it will be demonstrated, evaluated and communicated for the Swedish and European markets. IRIS Smart Cities is a five-year project where Gothenburg is one of three so-called Lighthouse cities that develop and test new solutions for urban development in energy, mobility and ICT. A total of 43 players from 9 countries collaborate. In Gothenburg, Johanneberg Science Park coordinates the project on behalf of the City of Gothenburg. Other project partners are Riksbyggen, Akademiska Hus, Chalmers, HSB, Trivector and Tyréns.