In response to growing demand for accessible, technically sound guidance, the International Institute of All-Natural Refrigeration (IIAR) has released a new CO₂ Refrigeration Fact Sheet—a concise overview of the use of CO₂, including safety considerations, system guidelines, and design considerations. Additional fact sheets for ammonia and hydrocarbons will follow.

IIAR Marketing Committee Chair, Stephanie Smith, said her committee was responsible for producing the fact sheets to help business owners choose which natural refrigerant applications may fit best for them.

“With more information available, it’s more important than ever to be able to summarize and keep it simple,” said Smith. “These IIAR fact sheets come with easy and basic information that IIAR is uniquely suited to provide to end users who are trying to make a decision, or to the general public who are trying to learn more about natural refrigerants.”

IIAR’s first goal, as always, is the creation of safety standards that promote more widespread adoption of ammonia, CO₂, and hydrocarbons. But with an extensive library of standards and technical handbooks, refrigerant-specific fact sheets can help experts and laypeople quickly compare refrigerants.

“IIAR decided to develop these fact sheets because there’s a need for a broader understanding of IIAR standards, with the increased use of hydrocarbons and CO₂, especially,” said Smith. “Highlighting the benefits of each refrigerant in a one-pager is a great resource. It gives anyone who’s interested quick, easier access to IIAR’s wealth of information.”

Carbon dioxide has long been recognized for its environmental advantages—zero ozone depletion potential and a global warming potential of just 1. But its adoption has been slowed by the absence of unified safety standards and building code recognition.

The inclusion of IIAR’s CO₂ standard into the ICBC framework changes that equation. The ANSI/IIAR CO₂-2021 Safety Standard for closed circuit carbon dioxide refrigeration systems was formally integrated into the International Code Council’s Building Codes (ICBC) in 2024 – a move that signals growing institutional support for low-GWP refrigerants and the infrastructure needed to deploy them safely.

Now, architects, engineers, contractors, and code officials have a clear, codified reference for designing and inspecting CO₂ systems. This reduces regulatory ambiguity and accelerates adoption across commercial and industrial sectors. But it has also broadened the interest in CO₂ generally, beyond the industrial refrigeration industry into applications like district heating and cooling, where the wealth of IIAR standards and information may prove useful.

And within the world of industrial refrigeration, CO₂ is growing more attractive for factors like its lower energy consumption, said Smith. “The next step is getting this information, like the energy efficiency payoff of CO₂, into an easier format to use and then provide it to others.”

“IIAR’s fact sheets are a good place to start if you don’t know where to start and you need basic information on refrigerants,” she added. The release of IIAR’s fact sheet is a timely addition to IIAR’s resources, said Smith. With regulatory pressure mounting, industry professionals are seeking natural refrigerants that balance performance, safety, and sustainability. CO₂ fits the bill, but its unique thermodynamic profile and operating characteristics require specialized knowledge.

IIAR’s fact sheet bridges the gap between technical depth and practical accessibility. It’s tailored for engineers, technicians, facility managers, and policymakers who need a reliable snapshot of CO₂’s capabilities and constraints—without wading through dense standards or textbooks.

Here’s what readers will find most useful:

Refrigerant Profile

• Chemical name: Carbon Dioxide (CO₂)

• ASHRAE designation: R-744

• Ozone Depletion Potential (ODP): 0

• Global Warming Potential (GWP): 1
(benchmark value)

• Safety classification: A1 (non-toxic, nonflammable)

• Thermodynamic Characteristics

• Operates at high pressures, especially in
transcritical systems

• Excellent heat transfer properties,
enabling compact system designs

• Requires specialized components rated for
CO₂ pressures

System Types

• Subcritical systems (often cascade with
ammonia or HFCs)

• Transcritical systems (common in
supermarkets and heat pumps)

• Secondary loop systems (CO₂ as a fluid in
indirect systems)

Advantages

• Environmentally benign: no ozone
depletion, negligible climate impact

• Readily available and inexpensive

• High volumetric cooling capacity
Challenges

• High operating pressures demand robust
system design

• Efficiency can drop in warm climates
without proper optimization

• Requires training and familiarity with CO₂-
specific safety protocols

The fact sheet also references IIAR’s CO₂ Safety Standard, the first of its kind, which outlines best practices for system design, installation, and operation. This standard complements the fact sheet by offering deeper guidance for facilities transitioning to CO₂ or expanding its use.

The fact sheet is more than a technical summary, said Smith, it’s more of a strategic tool. As CO₂ adoption accelerates across food retail, cold storage, and industrial processing, stakeholders need clear, credible information to guide investment and training. IIAR’s fact sheet helps normalize CO₂ as a mainstream refrigerant, reinforcing its role in a low-GWP future.

IIAR said the organization will release the CO2 fact sheet along with the new Ammonia and Hydrocarbons fact sheets in September 2025.