Four years ago, when too much snow made the roof collapse at the Gimo Arena in Osthammar, Sweden, the municipality had two options. Tear it down, or restore it. When they restored it, they did using C02 as both their primary and secondary refrigerant, marking the start of a revolution in the operations of ice rinks in Sweden.
For Lasse Karlsson, the Technical Contact for the Municipality of Osthammar, tearing what was left of the old barn down seemed evident — especially when considering the extent of the damage the collapsed section of roof had made. The roof would need replacing, but so would the concrete floor where the collapsed roof landed, and the refrigeration equipment below the pad. It looked like the 31-year-old rink’s days were over.
But the people of Osthamar had other plans.
The Gimo Arena was one of just two indoor single pads in this municipality, an hour’s drive or so north of Stockholm. Without it, the figure skaters and drop-ins would be in a bind, as would the couple dozen hockey teams that use the arena. And, like many northern countries, hockey is one of the few activities that makes the short days of winter a bit more bearable.
“We talked about not reconstructing it, but there was too much resistance to that politically,” Karlsson says. “So we decided that if we’re going to build it again, we really need to worry about the energy savings.”
“And then I called Jörgen.”
Jörgen Rogstam is the 48-year old Managing Director of EKA, an engineering firm with 15 years of C02 experience for projects in the automotive and supermarket industries. What Rogstam proposed, and Karlsson had to convince the Osthammar town council of, ended up being the first arena to use transcritical C02 refrigeration in Europe.
Essentially every ice rink could be heat independent if you’re able to take care of the recovered heat in a good way.
— Jörgen Rogstam
“We had to prove to them that more we had to invest, the more we would save,” Karlsson recalls. “Yes, it was a more expensive solution at the time. But we were able to prove that this is the way we have to do it because we have to save energy,”
When the Gimo Arena reopened three years ago, it was an anomaly on the Swedish indoor ice arena landscape, using carbon dioxide refrigerant for both the rink’s primary and secondary refrigeration functions. This fall, Gimo Arena will no longer stand alone: around 15 indoor ice arenas in Sweden will be running with C02 for the refrigeration machinery or the floor, or both.
Today, Rogstam’s company specializes in making ice arenas energy efficient. He sees that C02 is transforming the ice arena industry. Rogstam says much of that transformation is due to access: with C02 refrigeration applications blossoming in other industries — especially grocery stores — the costs are no longer restrictive. And, with more demand comes more skilled personnel. The barriers to entry are being torn down.
Heat Recovery: The Big Gain with C02
Rogstam says the big gain with C02 is on the heat recovery side “and that’s irregardless if you’re using it in the floor or not.” Gimo Ishall has been running on C02 for three years now, and by using the excess heat, they’ve been able to cover all the heating demands in the ice rink. In fact, 30% of the available heat is still available and that’s why Karlsson is busy with a new project which will port some of that reclaim heat for the swimming pool 150 metres up the road, and use it for heating the change rooms and the hot water for the showers for the Gimo football pitch.
One of the big differences between ice arenas in North America and ice arenas in Europe is in Europe, most arenas are powered by electricity only, not a blend of electricity and natural gas/propane/heating oil. Because of this, a typical single pad’s electricity consumption is around 1 million kWh/year. Karlsson has been tracking his arena’s energy spend, which has dropped to over half as much as what it was with the old ammonia system.
Rogstam, who co-authored a technical feature for ASHRAE called Cooling and Heating Ice Rinks with C02 says the crop of ice rinks moving to C02 marks a paradigm shift in the business.
“C02 is something very different with very different possibilities in terms of energy,” he says. “It’s nothing exotic that we use here, it’s a matter of knowing the technology, the possibilities and then doing it. And it’s going to happen more now because we can see what we’re going to save in money.”