The energy grid of Raksila Sports Centre will halve the carbon emissions from buildings

Sweco prepared an energy vision for Raksila Sports Centre in Oulu. The resulting energy grid made up by the ice hall, swimming hall and Oulu Hall, all owned by the City of Oulu, will recycle condensation heat, which will reduce the area’s carbon emissions by half and save up to 200,000 euros each year.

Oulu is involved in the Energy Wise Cities project, which seeks local means of reducing carbon emissions. The site with the largest potential for this in Oulu is Raksila Sports Centre. “The ice and swimming halls are the two City facilities that consume the most energy,” says the City of Oulu’s energy specialist Johanna Mäkelä. When the third City-owned facility, Oulu Hall, is counted in, the buildings consume as much energy as 10 residential blocks. “The energy-saving measures taken in Raksila have a huge impact on the City’s climate goals.”

The swimming hall and ice hall are a perfect match

The City of Oulu commissioned Sweco to prepare an energy vision for Raksila Sports Centre, with the aim of determining the area’s energy flows and opportunities for recycling them. “Our first step was to review the operation, energy consumption and energy waste of the area’s buildings,” says Timo Heikkilä, Sweco’s specialist in sustainable and smart construction. “Only after familiarising ourselves with the details of each building can we form an overview of the energy economy.”

The hourly energy consumption of the buildings was linked to other data, such as weather data. After this, the three-building complex was examined hour by hour. “We explored three different options, the first of which was directing the ice hall’s condensation heat into the district heating network,” says Heikkilä. However, this solution proved to be economically challenging compared to the other options.

On the other hand, a heating and cooling grid shared by the three buildings worked like a dream. “The ice hall and the swimming hall are a perfect match, since one needs constant cooling while the other needs constant heating,” Heikkilä says. With heat pump technology, condensation heat from the ice hall warms up the swimming hall for most of the year, and even Oulu Hall gets its share of the heating.

The energy vision revealed that the benefits of the three-building energy grid could be further increased by updating the ice hall’s aged building services. In addition to this, the vision explored the potential of solar power. “Instead of on the buildings themselves, solar panels could be placed in the Raksila park area, which is visited annually by over a million people. Doing so would also benefit the city’s image,” Mäkelä says.

Purchased heating energy to be reduced by 90%

Mäkelä was pleasantly surprised by both the results of the energy vision and the process itself. “The energy vision was prepared very quickly and conveniently from the perspective of the City. All I had to do was submit the order and listen to the results, which were much better than I was expecting.”

According to the energy vision, the three-building energy grid will reduce the amount of heating energy purchased by up to 90 per cent. For the swimming hall, this means annual savings of 120,000 euros, and for the entire area, 200,000 euros. The condensation heat will produce almost seven gigawatt-hours of energy, thanks to which only one gigawatt-hour of district heating will be needed. “The energy grid will thus reduce the buildings’ carbon footprint by half,” Heikkilä says.

It was crucial for the City’s decision-making that the pay-off period of the energy grid’s implementation is only six years. “A pay-off period of less than 10 years is a clear cut-off point in terms of whether measures will garner support,” Mäkelä states. “All of the measures suggested in the vision have already been integrated into the project plan for the renovation of Raksila swimming hall.”

The plan is to also apply the solution model to other swimming halls in Oulu. “One new swimming hall is currently in the project planning stage, and we have already been in contact with the energy plant about developing a similar energy grid for it,” Mäkelä says.

Potential for many cities and municipalities

The Raksila energy vision has garnered a great deal of interest among Finnish cities and interest organisations. “The results have positively surprised many municipalities,” Mäkelä says.

Heikkilä sees the City of Oulu as a pioneer, but other cities also show potential in areas where a single operator owns multiple properties. “In many cases, one building needs heating and another needs cooling, so this point of view should be expanded from an individual plot to the block level.”

Usually, area-specific energy analyses do not face challenges with technology or lack of knowledge, but with the ownership of the buildings. “Contract-wise, it is much more complicated to plan a solution with multiple property owners,” Heikkilä says. “Then again, energy grids provide opportunities for cooperation and synergy benefits, even between multiple operators.”