As environmental regulations tighten and energy efficiency becomes a top priority, many commercial and industrial refrigeration operations are turning to CO₂ refrigeration systems as a modern, eco-friendly alternative. But CO₂ systems aren’t just a drop-in replacement for traditional refrigerants—they come with a unique set of considerations that can impact performance, reliability, and long-term ROI.
In this blog, we’ll break down the basics of CO₂ (carbon dioxide) refrigeration in clear, practical terms. Whether you’re upgrading equipment, building a new facility, or exploring sustainable refrigeration options, this guide will help you understand what makes CO₂ systems different—and how to maximize their potential in your operation.
Why Choose CO₂ as a Refrigerant?
CO₂, also known as refrigerant R-744, is gaining momentum in the refrigeration industry for good reason:
- Low Environmental Impact: CO₂ has a Global Warming Potential (GWP) of just 1—compared to traditional refrigerants like R-404A, which has a GWP over 3,900.
- High Energy Efficiency: In the right conditions, CO₂ systems can outperform conventional refrigeration systems, particularly in cooler climates.
- Regulatory Compliance: CO₂ systems future-proof your facility by aligning with evolving environmental and refrigerant phase-down regulations.
However, CO₂ is not without its challenges—especially in terms of system design, pressure management, and climate adaptability.
Key Differences: How CO₂ Systems Operate
CO₂ refrigeration systems function differently than traditional systems, and understanding these differences is key for informed decision-making.
- Higher Operating Pressures
- CO₂ operates at much higher pressures than other refrigerants. While this might sound alarming, today’s systems are built with specialized components designed to handle these conditions safely and reliably. Proper engineering and installation are essential.
- Two Modes of Operation: Subcritical and Transcritical
- Subcritical Mode: In cooler climates or during colder months, CO₂ behaves like traditional refrigerants—operating at manageable pressures with efficient heat exchange.
- Transcritical Mode: In warmer environments, CO₂ enters a supercritical state, where it no longer behaves as a typical liquid or gas. This mode requires more advanced system controls and heat rejection strategies to maintain efficiency.
- Unique Thermodynamic Properties
- CO₂ has a triple point and critical point that impact system design. These characteristics influence how heat is removed and how pressure is managed across the system, particularly in variable climates.
- Triple Point: The temperature and pressure where CO₂ can exist as a solid, liquid, and gas.
- Critical Point: The temperature where CO₂ becomes a supercritical fluid.
The American Innovation and Manufacturing (AIM) Act, enacted in December 2020, has brought significant changes to the refrigeration industry. As we navigate through 2025, the first set of restrictions under the AIM Act are now in effect, aiming to phase down the production and consumption of hydrofluorocarbons (HFCs) by 85% by 2036. These regulations are crucial for reducing greenhouse gas emissions and transitioning to more environmentally friendly refrigerants.
One of the key aspects of the AIM Act is the Technology Transition Rule. It impacts the repair and servicing of refrigerated display cases. The rule specifies that repairs are permissible unless they result in the creation of a new system. This means that while existing display cases can continue to operate and be serviced, certain extensive repairs may be restricted. For instance, assembling a system for the first time from used or new components, increasing the cooling capacity of an existing system, or replacing 75% or more of evaporators and 100% of the compressor racks, condensers, and connected evaporator loads are considered new installation
Understanding these repair restrictions is essential for businesses to ensure compliance and avoid potential penalties. As we move forward, staying informed and adapting to these regulations will be key to maintaining operational efficiency and environmental responsibility. This blog will help navigate the repair restrictions of refrigerated display cases.
Last month, we discussed the ways in which industrial and commercial refrigeration systems can achieve greater energy efficiency using modern components. This month, we will delve into the advancements in commercial reach-in freezers and coolers, commonly known as refrigerated display cases within the industry. We will explore how these units have been optimized for efficiency and effective cooling with the integration of the latest refrigeration technology.
As energy costs rise, regulations evolve, and consumer demand for environmentally friendly solutions increases, evaluating your current commercial or industrial refrigeration system for a potential upgrade increases in importance. When considering an upgrade, several factors – such as the current condition of your equipment, maintenance costs, energy efficiency, and refrigerant type must be evaluated. Each of these factors play a role in determining the cost effectiveness of an upgrade.
Now that we have crossed into 2025, the first restrictions of the American Innovation and Manufacturing (AIM) Act are now in effect. The AIM Act of 2020 allows the EPA to restrict the production, import, and use of hydrofluorocarbons (HFCs). HFC refrigerants have a high global warming potential (GWP) and are being phased down by 85% through 2035.
The Refrigerants allowed by the AIM Act are not direct substitutes for HFC refrigerants. Refrigeration systems require different components, piping and programming with each refrigerant. The performance of refrigeration systems is influenced by the external ambient temperatures.
Equipment installed before restrictions go into effect are allowed to maintain operation throughout their useful life. This includes service, parts, and refrigerant. However, the availability of each is dependent on the manufacturer.
Retrofitted equipment and new installations have their own regulations and definitions. Retrofitted equipment, replacing at least 75% or more of the evaporators and 100% of the compressor racks, condensers, and connected evaporator loads of an existing system, will need to follow the restrictions for a new installation. For more information on the AIM Act and state regulations, visit our Refrigerant Regulations webpage.
On June 8, 1961, George Johnson, Duke Wegner, and K. Hirata founded Zero Zone in a rented barn in Pewaukee, Wisconsin. Their dedication to customer satisfaction, through personalized support and customizable options, has fostered a legacy of trust over six decades. Today, we remain committed to upholding these values as we continue to serve our community.
At Zero Zone, one of our core values is the care and support of our family. We recognize the importance of people; support and empathy for everyone we engage with are central to our culture. Whether you are an employee, customer, or partner, Zero Zone is committed to being responsive to your needs.
As the American workforce ages and new technologies arrive in the industrial and commercial refrigeration industries, training a new generation of workers becomes essential. For that reason, Zero Zone collaborated with Apprentice Now to create an apprenticeship program to train new technicians. The 14 candidates that were selected finished their 10-week program on December 3. Although they have graduated from the program, these students will continue their hands-on education in their careers.
Zero Zone helped train these technicians without the expectation that students would take a position with us. They will have the opportunity to apply for a position with Zero Zone or other companies within the industry. Apprentice Now aids the new technicians with placement in open roles throughout the industry. Recognizing the demand for technicians in the industrial and commercial refrigeration industry, we see this partnership as a proactive step.
Sustainable business practices are rapidly gaining priority as rising energy costs, evolving regulations and increasing consumer demand for environmentally friendly solutions drive change. In the refrigeration industry, the choice of refrigerant directly affects both energy costs and regulatory compliance. This blog will explore the advantages and disadvantages of low-global warming potential (GWP) refrigerants; Natural and Hydrofluoroolefin (HFO).
In 2002, a severe drought agonized 33% of the contiguous United States. Crops and pastures were ruined, wells ran dry, and reservoirs were drained. In Colorado, over 3 million people lost their water security. Water restrictions were put in place. Outdoor lawn watering, accounting for half of annual residential water use, could only be done once a week and was scheduled by address numbers. Swimming pools could not be filled during one of the warmest summers on record. After the drought broke, planning for the next one became a priority. An expansion project began on Colorado’s Gross Reservoir Dam, located in Boulder County, to prevent water scarcity in the future.
The dam is going to be raised by 131 feet (totaling 471 feet) to increase the reservoir’s capacity by 25 billion gallons of water. After the dam’s expansion, it will be 3 times its current size and the tallest concrete dam in Colorado. Although this project has many challenges, one in particular caught the attention of Zero Zone: the heat concrete produces as it cures.
The Hybrid™ merchandiser provides the flexibility of a self-contained display case while maintaining the durability and sales capability of those in large supermarkets. Each Hybrid™ merchandiser inherits the traits of its remote counterpart and has all the necessary refrigeration components mounted on top of the display case. These cases require minimal effort to install. After connecting the remote condensing unit to the display case, they are ready to be energized for operation. With medium- and low-temperature options, you can display beverage, bakery, dairy, deli, floral, frozen food, meat, produce, or seafood products in an environment that will keep them fresh.
Zero Zone Hybrid™ merchandisers provide benefits for a store of any size. They allow small format stores to effectively and efficiently use their floorspace for merchandising products rather than taking up valuable real estate for the refrigeration system. Large format retailers can add a Hybrid™ merchandiser to the sales floor without increasing the installed system’s load or the need for additional refrigeration piping.