Comparing Synthetic vs. Natural Refrigerants: A Comprehensive Guide for Lab Managers

Authored by: Dr. Dirk Frese, VP of Sales, Marketing & Service

Thinking about switching your lab’s temperature control systems to natural refrigerants?

As regulations evolve and more organizations prioritize long-term efficiency and environmental responsibility, many labs are reassessing the refrigerants used in their equipment. This guide compares synthetic and natural refrigerants, highlights performance and safety differences, and outlines what to consider when planning your next upgrade.

Introduction

Temperature regulation has evolved dramatically in laboratory environments. In the past, Bunsen burners heated water, oil, or sand baths, and heating mantles encased glass vessels—an approach that often introduced safety risks depending on the chemicals in use. Cooling methods were equally rudimentary: running tap water through condensers, ice-filled buckets, dry ice, or liquid nitrogen provided makeshift thermal control, albeit with limited precision and no programmability.

Today, laboratory professionals have access to advanced thermal regulation systems. Precision heaters, chillers, and circulators offer broad temperature ranges from -100 °C to +350 °C, with exceptional stability (±0.01 °C). These systems are equipped with intelligent electronics and software that enable automated ramp profiles, real-time compensation for exothermic or endothermic reactions, and remote data logging and transfer.

Laboratories are increasingly aligning with global environmental goals by adopting sustainable practices. Labs are inherently resource-intensive, consuming high volumes of energy and water and generating significant single-use waste.

Factors driving this transition include:

Environmental Accountability
Regulatory Mandates
Economic Incentives

Particularly in the pharmaceutical and biotech sectors, organizations are committing to net-zero carbon targets and seeking instruments that reflect their ESG (Environmental, Social and Governance) values.

In response to climate change, refrigerants with high Global Warming Potential (GWP) or Ozone Depletion Potential (ODP) are being phased out. This transition affects laboratory chillers and circulators, which traditionally used synthetic refrigerants like hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs).

Today’s alternatives include:

Natural refrigerants, such as hydrocarbons, carbon dioxide, and ammonia
Alternative cooling technologies, like Peltier-based thermoelectric systems

This guide focuses on natural refrigerants, highlighting their performance, sustainability impact, and regulatory implications.

Types of Refrigerants:

Synthetic Refrigerants

Hydrofluorocarbons (HFCs)

Though they replaced ozone-depleting CFCs and HCFCs, HFCs have high Global Warming Potential (GWP) and contribute to climate change by trapping heat in the troposphere (up to 12 km), where weather systems occur. This layer is isolated from higher atmospheric layers like the stratosphere (12–50 km) and mesosphere (50–85 km), causing heat to accumulate and intensify the greenhouse effect.

Hydrofluoroolefins (HFOs)

HFOs are unsaturated HFCs containing at least one double bond. This makes them more reactive, resulting in shorter atmospheric lifespans and zero ODP.

Common Examples of HFO Refrigerants:

R-134a: Moderate GWP, widely used
R-410A: High-pressure blend of R-32 and R-125
R-32: Often used as a component in blends

In addition to refrigeration, HFCs are also used in insulating foams, aerosol propellants, solvents, and fire suppression systems.

Natural Refrigerants

Natural refrigerants come from naturally occurring environmental substances, such as ammonia, carbon dioxide, and hydrocarbons. They are characterized by zero ODP and very low GWP.

Ammonia (R-717)

Ammonia, also known as R-717, is a highly efficient natural refrigerant with zero Global Warming Potential (GWP) and zero Ozone Depletion Potential (ODP). While environmentally ideal, it poses safety challenges: it is toxic, corrosive, and mildly flammable, requiring strict precautions.

Due to these risks, ammonia is primarily used in industrial refrigeration systems and is generally unsuitable for precision lab environments, where safety and compact design are essential.

Carbon Dioxide (R-744)

Carbon dioxide, or R-744, is a non-flammable and non-toxic natural refrigerant with a Global Warming Potential GWP of 1, making it the baseline reference for environmental impact assessments. It is safe and environmentally benign, but operates under very high pressures, which introduces added complexity in system design, cost, and safety considerations.

While it performs well in many applications, CO₂ systems have a lower temperature limit of -40 °C, which can restrict their use in ultra-low temperature environments.

Common Examples of Hydrocarbons (HCs):

Propane (R-290)
Isobutane (R-600a)
Propylene (R-1270)
Ethane (R-170)

Hydrocarbons are highly efficient, with zero ODP and low GWP values. Because they are flammable, they require specific safety measures and training for technicians working on these units. To ensure gas concentrations stay below the lower explosive limit (LEL) in the event of a leak, the room must be large enough to safely accommodate the refrigerant in use.

The table below shows these requirements for JULABO instruments running on natural refrigerants:

These refrigerants are ideal for precision laboratory cooling, as seen in JULABO’s VALEGRO series:

Environmental Impact of Refrigerant Choices

Environmental metrics such as Global Warming Potential (GWP) and Ozone Depletion Potential (ODP) are key when evaluating refrigerants for lab applications. GWP compares a substance’s heat-trapping effect to that of CO₂, which is assigned a baseline value of 1 over a 100-year period. Older HFCs like R-134a can reach GWPs as high as 4,700, while newer HFOs often fall below 1. Natural refrigerants, such as hydrocarbons and CO₂, remain at or near the baseline, offering a significant climate advantage.

ODP measures a substance’s potential to damage the ozone layer. While HFCs have minimal but measurable ODP, HFOs and natural refrigerants have zero ozone impact, making them ideal for environmentally conscious labs.
Atmospheric lifespan also matters. HFCs persist for decades, whereas HFOs degrade within days. Natural refrigerants such as CO₂ and hydrocarbons either break down quickly or are already part of the natural cycle, resulting in minimal environmental burden.

These advantages make natural refrigerants a compelling choice for labs aiming to reduce their environmental footprint while preparing for stricter regulatory landscapes.

Performance Comparison

Natural refrigerant-based systems demonstrate strong performance metrics that make them highly competitive with—and often superior to—their synthetic counterparts. One of the most significant advantages is energy efficiency. Systems using natural refrigerants can deliver up to 15% greater energy efficiency, resulting in lower power consumption and reduced operating costs over time.

Cooling capacity is another area where these systems excel. For instance, the JULABO DYNEO DD-1201F model offers up to a 25% improvement in cooling output compared to previous-generation systems using synthetic refrigerants. This enhancement ensures that even the most temperature-sensitive applications are supported with greater precision and responsiveness.
Temperature flexibility is also a key benefit. Natural refrigerant systems in JULABO’s product lineup are engineered to achieve a broad thermal range from -93 °C to 350 °C, making them suitable for a wide array of laboratory applications, from botanical extractions to high-temperature chemical reactions.

When it comes to safety parameters, toxicity levels of natural refrigerants range from low to moderate, depending on the specific compound in use. Hydrocarbons such as propane and isobutane, for example, are classified as low-toxicity but present high flammability risks, necessitating appropriate safety measures in equipment design and handling.
Carbon dioxide systems, while non-flammable and non-toxic, operate at significantly higher pressures than conventional refrigerants.This requires robust, pressure-resistant components and careful system engineering to ensure safety and long-term reliability.

Regulatory Landscape

Global and Federal Regulations

Regulations change and differ in various geographies. Below is a list of applicable rules and regulations that define how and when synthetic refrigerants are being phased out.

For example, Section 2 of California regulation SB1206 adds Section 39735 to the state’s Health and Safety Code. It mandates that refrigerants must not exceed a GWP of 2200 as of January 1, 2025; 1500 by January 1, 2030; and 750 by January 1, 2033.

Montreal Protocol (1987) – Phased out ODP substances like CFCs and HCFCs
Kigali Amendment (2016) – Mandated gradual phase-down of HFCs worldwide
U.S. Regulations (EPA):
AIM Act: Phase down HFCs by 85% by 2036
SNAP Program: Lists acceptable/unacceptable alternatives
EPA Section 608: Requires handling and recovery standards
40 CFR Parts 705 & 82: Regulatory framework for PFAS and natural refrigerants

State-Level Mandates:

California – Title 17
New York – Part 494
Washington – CR 102
Oregon – SNAP plus state-specific rules
Canada – Governed by Environment and Climate Change Canada (ECCC)
Compliance Impacts:
Charge limits (≤150g per unit)
Sales/import restrictions
Virgin vs. reclaimed refrigerants
Labeling and transport guidelines
Applicability based on manufacturing date and equipment classification
Interpretation Challenges

Laboratory equipment often falls outside the standard HVAC and appliance frameworks, requiring case-by-case evaluation.

Green Lab Certification

Achieving Green Lab Certification has become an important step for laboratories committed to sustainability. Programs like My Green Lab assess lab practices, including refrigeration, to encourage reductions in environmental impact.

One major requirement is the use of low-GWP refrigerants or thermoelectric cooling systems. These technologies help minimize greenhouse gas emissions and align with decarbonization goals. Additionally, labs must consider the full lifecycle of equipment, especially end-of-life management, where proper refrigerant recovery and disposal are crucial to prevent atmospheric release. JULABO offers special decommissioning services to support proper refrigerant handling and disposal.

Partnering with manufacturers that provide transparent refrigerant data and support sustainable system design, such as JULABO, can greatly ease compliance. Integrating these technologies supports certification efforts and helps strengthen a laboratory’s reputation for environmental responsibility.

Cost Analysis

When considering the adoption of natural refrigerants in laboratory equipment, it’s essential to examine both the upfront and ongoing costs. Fortunately, the initial investment for natural refrigerant systems is generally comparable to that of systems that rely on synthetic alternatives. One exception is carbon dioxide systems, which often require specialized, pressure-resistant components due to CO₂’s high operating pressures. These added requirements can increase initial equipment costs.
From an operational standpoint, natural refrigerants present an attractive value proposition. These systems typically consume up to 15% less energy than their synthetic counterparts. For laboratories that operate temperature control systems continuously or frequently, this energy efficiency translates into substantial savings over time, particularly in regions with high electricity costs.

Another cost-related advantage lies in the refrigerants themselves. When systems require recharging, due to maintenance or a leak, natural refrigerants are significantly less expensive, often costing up to three times less than synthetic options. While the day-to-day impact may be small, the long-term savings can be substantial, especially in large facilities managing multiple systems.

Implementation Challenges

Implementing natural refrigerants in laboratory environments, while beneficial, comes with its own set of challenges. One of the most common concerns is equipment compatibility. Fortunately, natural refrigerant-based systems such as those offered by JULABO are designed for seamless integration. No modifications are needed to existing application setups, fluid lines, or temperature bath contents. Fluids such as water, ethylene glycol, or silicone oils used in temperature baths remain fully compatible with these systems.

Retrofitting existing synthetic refrigerant systems to use natural refrigerants is generally not feasible. This is due to fundamental differences in refrigerant characteristics, such as bubble points and lubricant compatibility, which require completely redesigning internal components like compressors and valves. As a result, adopting natural refrigerants typically means purchasing new systems rather than upgrading existing ones.

Training is another important consideration. While end users do not require any specialized training to operate natural refrigerant-based units, maintenance personnel and service technicians should receive supplementary instruction. In particular, the flammability of hydrocarbon refrigerants requires awareness of additional safety protocols. Certification requirements for handling these refrigerants vary across jurisdictions, so it is advisable to consult local regulatory authorities when developing technician training programs.

Conclusion

In summary, transitioning from synthetic to natural refrigerants is both a practical and responsible choice for modern laboratories. Natural refrigerants offer significant environmental advantages, including zero ozone depletion and dramatically lower global warming potential. They are also energy efficient, often improving performance metrics like cooling capacity and operational cost.

While regulations continue to evolve, the direction is clear: institutions that act now will benefit from systems that meet or exceed emerging compliance standards. For laboratories pursuing Green Lab Certification or carbon neutrality, natural refrigerant systems are a vital piece of the solution.

Lab managers are encouraged to evaluate their existing infrastructure and consider integrating equipment that supports long-term sustainability goals. Companies like JULABO are actively innovating in this space, offering advanced solutions that balance performance, safety, and compliance. The path forward is clear: natural refrigerants are not just a viable alternative—they are a superior choice for a cleaner, more efficient future in scientific research.