Nearly 900 district energy professionals from 30 countries convened in Minneapolis, Minnesota, for the Annual IDEA District Energy Conference and Trade Show, held June 2–5, 2025, where the International Institute of All-Natural Refrigeration (IIAR) was invited to attend and contribute to IDEA’s business meeting.

The meeting with IIAR was organized to explore ways for IIAR members and equipment manufacturers to expand the use of natural refrigerants—particularly in heat pumps and chillers—across the district heating and cooling industry. While the broader discussions covered natural refrigerants in general, Robert Croghan, CEO of Cascara Energy, said he was especially pleased to see momentum building for CO₂ as a potential district energy vector fluid, offering an alternative to water in certain applications.

Organized under the theme “Aggregate, Integrate, Innovate,” the event showcased how centralized thermal systems are evolving to meet the demands of a decarbonizing, digitalizing, and increasingly electrified world.

“Aggregation, integration, and innovation are a combination of qualities that are unique to district energy,” said Rob Thornton, IDEA President and CEO. “Together, these three capabilities enable the technology’s ability to deliver resilient, efficient, reliable, and sustainable energy solutions for cities and communities worldwide.”

IIAR represented natural refrigerants on the IDEA exhibit hall floor, where Croghan noted that CO₂ heat pumps and chillers are rapidly gaining momentum across the refrigeration and HVAC industries. “We’re seeing adoption across all scales—from single-family homes to large-scale industrial systems of 50 MW and above,” he said.

“Everyone is coming out with a heat pump solution now, and CO₂ as a natural refrigerant is being adopted quickly,” Croghan continued. “We’re looking closely at how people are customizing CO₂ applications, and it’s an important area to focus on because the technology is rapidly maturing.”

Croghan added that the equipment and infrastructure needed to make CO₂ heat pump and chiller-based district energy systems feasible “is available now, whereas it wasn’t before,” thanks to the convergence of three trends: the widespread adoption of CO₂ in the heat pump and chiller markets, the growth of carbon capture and utilization projects, and the presence of established large-scale CO₂ pipeline networks already in operation.

“This combination means we now have both the technology and the transport infrastructure to enable large-scale CO₂ district energy systems. The environment for carbon capture, use, storage, and transport is well established, and CO₂ is already present within the property line of many customers, making it a far more practical and cost-effective option for district energy.”

“In the past, the cost of building dedicated CO₂ pipelines was prohibitive,” said Croghan. “Today, with established infrastructure, available equipment, largescale compressors, and the necessary pipe systems already in place—and with clear IIAR standards—the pathway to deployment is much more practical.”

Croghan said he was especially encouraged to see IIAR in attendance at the IDEA event because the regulations and standards that have been developed around CO₂ are accelerating the adoption of heat pumps and chillers using natural refrigerants.

“It’s encouraging to see IIAR at IDEA, as they are a leading resource for CO₂ standards and play a key role in establishing its credibility as a large-scale refrigerant.

Expanding education around CO₂ supports industry progress,” he said, adding, “Large-scale district cooling can benefit greatly from CO₂ based systems, given theirefficiency, environmental advantages, and growing regulatory support.”

Wayne Barnett, Head of Public Policy and External Affairs at Cordia Energy, who facilitated the business development meeting where IIAR representative Tony Lundell was invited to speak, said his interest in IIAR was in how the two organizations could collaborate to extend IIAR’s educational resources into new markets.

“We’ve had good conversations and follow up with IIAR and we’re having discussions around expanding this effort,” said Barnett. “Our core business is thermal district heating and cooling, which makes IIAR a natural partner. As a recognized part of the regulatory and standards framework, IIAR is well-positioned to extend its educational resources on CO₂ and other natural refrigerants into broader policy and commercial discussions and to build awareness among stakeholders well beyond the industry, supporting both best practices and decarbonization goals.”

Tony Lundell, IIAR’s Senior Director of Standards and Safety, said IIAR was able to bring information about natural refrigerants—such as challenges and best practices—to the IDEA conference, where many attendees were exploring the new possibilities presented by natural refrigerant use in district heating and cooling.

“This was an exciting event for IIAR because it was a chance for us to extend our years of rigorous standards development and natural refrigerant knowledge to a new audience,” said Lundell. “Now, as these new applications for natural refrigerants are emerging, it’s a good time to think about how we can work together and advocate together going forward.”

The integration of diverse energy sources, including renewables, waste heat, combined heat and power, and even data center
thermal loads, earned focus at the event. The District Thermal Energy Networks Workshop examined how utilities and municipalities are coupling thermal systems with electricity, natural gas, and wastewater networks to create flexible, low-carbon infrastructure.

Meanwhile, the District Energy and Data Centers Workshop explored the convergence of two rapidly growing sectors: digital infrastructure and urban thermal systems. With data centers proliferating to meet global demand, their need for firm power and constant cooling— and their production of massive volumes of low-grade heat—makes them ideal candidates for district energy integration, said IDEA in a statement.

Speakers from global data center operators and government agencies discussed heat export programs, co-location strategies, and regulatory frameworks for grid infrastructure. Technology providers showcased innovations in CHP, thermal storage, and energy optimization, positioning district energy as a key enabler of sustainable digital growth, said IDEA, adding “data centers and district energy go better together.”

The conference also featured plenary panels with CEOs from leading district energy companies, an Innovation Awards ceremony, and technical tours of Cordia’s Main Plant and District Energy in St. Paul, Minnesota. Keynote speaker Joseph Majkut of CSIS offered a perspective on energy security and climate resilience, framing district energy as critical infrastructure in an era of extreme weather and shifting federal mandates.