Which Refrigerant is Used in Cold Storage?
Cold storage facilities, including warehouses, cold rooms, and refrigerated distribution centers, rely on refrigeration systems to maintain low temperatures essential for preserving perishable goods such as food, pharmaceuticals, and chemicals. The choice of refrigerant—the substance that absorbs and releases heat in these systems—plays a critical role in efficiency, safety, environmental impact, and regulatory compliance.
As of 2026, ammonia (R717) remains the most widely used refrigerant in industrial cold storage applications, particularly in large-scale facilities. Its exceptional thermodynamic properties provide superior heat absorption and energy efficiency compared to alternatives, resulting in lower operational costs over time. Ammonia has a global warming potential (GWP) of zero and does not deplete the ozone layer, making it environmentally favorable in terms of climate impact. In the United States, for instance, approximately 85% of public cold storage warehouses historically utilize ammonia-based systems, a trend that persists due to its proven reliability in medium- and large-sized operations.
Despite its advantages, ammonia presents safety considerations. It is toxic and mildly flammable, necessitating specialized handling, leak detection systems, and trained personnel. These factors often confine its use to industrial settings with dedicated machine rooms, away from populated areas.
A significant shift is underway toward carbon dioxide (CO2, R744) as a primary refrigerant, especially in newer installations. CO2 offers a GWP of 1, excellent safety profile (non-toxic and non-flammable), and improving energy efficiency through advancements in transcritical and booster systems. Technological progress has made full CO2 systems viable for both freezing and low-temperature warehousing. Driven by regulatory pressures, CO2 is rapidly gaining adoption in modern facilities seeking lower lifetime costs and reduced environmental footprint.
Historically, synthetic hydrofluorocarbons (HFCs) such as R404A and R507A dominated smaller and some existing cold storage systems due to their ease of use and compatibility with direct expansion setups. However, these refrigerants possess high GWPs—often exceeding 3,000—contributing substantially to greenhouse gas emissions.
Global regulations have accelerated their phase-out. The U.S. Environmental Protection Agency’s rules under the American Innovation and Manufacturing (AIM) Act, effective from January 1, 2026, impose strict GWP limits: 150 for cold storage warehouses with refrigerant charges of 200 pounds or more, and 300 for smaller charges. Similar restrictions apply internationally through the Kigali Amendment to the Montreal Protocol. Consequently, high-GWP HFCs are prohibited in new systems, rendering them unsuitable for future installations. Existing facilities may continue using them, but retrofits increasingly favor natural alternatives.
Emerging options include low-GWP hydrofluoroolefins (HFOs) and blends, such as R454C (GWP 148) or R471A, classified as mildly flammable (A2L). These provide transitional solutions for certain applications but are less common in large industrial cold storage due to scale and efficiency demands.
In summary, while ammonia continues to predominate in established large-scale cold storage for its efficiency and cost-effectiveness, carbon dioxide is emerging as the preferred choice for new and sustainable systems. This transition reflects a broader industry movement toward natural refrigerants that balance performance, safety, and environmental responsibility. Facility operators must evaluate specific needs—including size, location, and temperature requirements—when selecting or upgrading refrigeration systems to ensure long-term compliance and optimal operation.