How to Choose a Sustainable Compressor

The HVAC&R (Heating, Ventilation, Air Conditioning, and Refrigeration) industry is undergoing a significant transition. As global temperatures rise and electricity demand continues to increase, regulators around the world are adopting more stringent environmental requirements. Regulatory developments such as the Kigali Amendment[1] and the revised EU F-gas Regulation (EU) 2024/573[2] are prompting manufacturers and system operators to re-evaluate heating and cooling systems.

Against this backdrop, one key question remains:

What makes a compressor sustainable?

Today, compressor sustainability is not defined solely by lower power consumption or the use of a low-GWP refrigerant. A broader perspective is often required—one that considers energy efficiency, refrigerant GWP (Global Warming Potential), and the environmental impact of equipment across its lifecycle. This article reviews several key criteria commonly used to evaluate sustainable compressors, including inverter technology, part-load efficiency, the transition to low-GWP refrigerants, and lifecycle assessment frameworks such as TEWI and LCCP.

The climate impact of an HVAC&R system can generally be considered in two categories. One is direct emissions, such as refrigerant leakage and end-of-life losses. The other is indirect emissions, associated with the electricity consumed during system operation.[3][6][7][8]

For this reason, evaluating a sustainable compressor may require more than reviewing refrigerant type alone. It may also involve consideration of real-world operating efficiency and total environmental impact across the lifecycle. This is why the industry commonly uses frameworks such as TEWI and LCCP.[6][7][8]

What Is TEWI?

TEWI (Total Equivalent Warming Impact) is a metric used to estimate the warming impact of a refrigeration or air-conditioning system over its lifetime by combining:
(1) the direct impact of refrigerant leakage and emissions, and
(2) the indirect impact associated with energy use during operation.[6]

A sustainable compressor may be understood as one designed to reduce both direct and indirect emissions while maintaining stable performance under actual cooling or heating conditions. One of the technologies often discussed in this context is the inverter, or variable-speed drive.

A conventional fixed-speed compressor typically operates at full output when needed and stops once the target condition is reached. Repeated On/Off control in this manner can create limitations under part-load conditions and may reduce the system’s flexibility in responding to changing demand.

An inverter compressor, by contrast, can adjust motor speed based on actual cooling or heating demand. Under lower load conditions, it can operate at a lower speed, which may allow more flexible load matching. In real operating environments, this characteristic may contribute to improved energy efficiency.[4][5]

One of the key concepts in compressor evaluation is part-load efficiency. This is because HVAC&R systems do not operate at 100% load all the time. Depending on weather conditions, occupancy, and time of day, they may spend a significant portion of operating hours under part-load conditions.[4]

Because of this, rated efficiency alone may not fully represent real-world performance. Systems may also need to be assessed based on efficiency under actual operating conditions rather than peak capacity alone. In particular, variable-speed systems are often evaluated under part-load and seasonal conditions, and related test and evaluation methods have evolved accordingly.[5]

If energy efficiency is one aspect of sustainability, refrigerant is another. For many years, the industry has widely relied on HFCs (Hydrofluorocarbons), and many of these refrigerants have relatively high GWP values and are increasingly subject to regulation.[1][2]

Today’s regulatory environment is encouraging a transition toward low-GWP refrigerants.[1][2] In this context, A2L refrigerants such as R-32 and R-454B, natural refrigerants such as R-290 (propane), and HFO-based alternatives are often discussed as possible options.[9][10][11]

This transition involves more than a refrigerant change alone. It may require broader changes in system design. Low-GWP refrigerants can have operating pressures and thermodynamic properties that differ from those of legacy refrigerants, and some A2L refrigerants are classified as mildly flammable.[10][11]

For this reason, a sustainable compressor may need to be designed not only for compatibility with low-GWP refrigerants, but also with relevant safety considerations in mind. Readiness for low-GWP refrigerants may therefore be associated not only with regulatory adaptation, but also with system-level suitability and safety.[1][2][10][12]

The transition to low-GWP refrigerants is not defined by environmental performance alone. Depending on refrigerant classification and flammability characteristics, system design, component configuration, leak mitigation, and safety devices may all need to be reviewed together.

ASHRAE provides reference materials on refrigerant designation and classification, while UNEP/ASHRAE resources help explain refrigerant safety classes.[10][11] IEC 60335-2-40 addresses product safety requirements for equipment such as heat pumps, air conditioners, and dehumidifiers, and UL materials also discuss the importance of refrigerant detection and related safety requirements.[12][13]

In other words, a sustainable compressor may be evaluated not only in terms of low-GWP refrigerant compatibility, but also in terms of alignment with relevant safety standards and technical requirements.

To assess sustainability more comprehensively, product specifications alone may not be sufficient. Engineers and related institutions commonly use TEWI and LCCP to evaluate the climate impact of HVAC&R systems.[6][7][8]

TEWI estimates both direct emissions from refrigerant leakage and disposal, and indirect emissions associated with the electricity required to operate the system.[6]

LCCP goes a step further by including the full lifecycle, from compressor manufacturing and transportation to refrigerant production, installation, maintenance, disposal, and recycling.[7][8]

One commonly cited observation from these frameworks is that, in many cases, indirect emissions from energy consumption can account for a substantial share of the total carbon impact of a system.[3][4][6][8] This suggests that sustainability may not be determined by low-GWP refrigerants alone; operating efficiency may also play a significant role.

Ultimately, a sustainable compressor may be evaluated from a system-level perspective that includes low-GWP refrigerant readiness, operating efficiency, leak management, and consideration of safety and technical standards.

The direction of HVAC&R technology transition is becoming increasingly clear. The EU F-gas Regulation is tightening restrictions on high-GWP equipment, while the global market is also moving toward low-GWP refrigerants and higher-efficiency systems.[1][2][4]

In this environment, compressor selection is no longer simply a component decision. For system operators, energy cost and maintenance efficiency may be important. For engineers, system performance and safety considerations may matter. For procurement teams and decision-makers, regulatory readiness and long-term investment value can be key evaluation factors.