FTE or ETE? Choosing The Smart Path to Better CO2 Refrigeration Efficiency
CO2 refrigeration has reached the point where the question is no longer whether it can work in demanding food retail environments, because we already know it can. The better question is how to make it work as efficiently as possible for the store, the climate, the load profile, and the operator’s long-term goals.
And that is exactly where technologies like FTE and ETE matter.
Both are designed to support better CO2 transcritical refrigeration performance. Both can help retailers move toward natural commercial refrigeration. Both speak to the same big issue: modern stores need refrigeration systems that are cleaner, smarter, and more efficient without becoming a maintenance headache.
They solve the same problem in different ways, so choosing the right path starts with understanding what each technology is built to do.
CO2 Refrigeration Is Strong, But Conditions Matter
CO2, or R-744, is a natural refrigerant with a lower environmental impact than many legacy refrigerants. That makes CO2 systems a strong fit for retailers planning around sustainability, compliance, and future refrigerant strategy.
CO2 transcritical systems also respond differently depending on operating conditions, and that is the tension. CO2 can be a cleaner refrigerant path, but the system still needs smart engineering to run efficiently, especially under tougher conditions.
This is where FTE and ETE come in.
FTE Focuses on Year-Round Efficiency
FTE stands for Full Transcritical Efficiency. The core value is its ability to improve CO2 system efficiency by increasing medium-temperature suction pressure, which reduces compressor power consumption.
In an independent case study, FTE was chosen by Lunds & Byerlys for the first U.S. installation in a cold-climate location. One reason it stood out was relative simplicity compared with other options like ejectors and parallel compression. Another was the opportunity for year-round energy savings, while many booster CO2 system efficiency options mainly help during hot weather.
That makes FTE a strong fit for operators who want CO2 efficiency gains across a broader portion of the calendar.
FTE’s year-round savings come from flooding evaporators in coolers, which allows medium-temperature suction pressure to increase throughout the year and reduces compressor power use.
In real store monitoring, the results were clear. CEE monitored the Lunds & Byerlys Highland Bridge system through October 2023, switching FTE on and off during the first year to compare operation. The analysis verified statistically significant measurable energy savings. Applied to typical weather data, FTE provided annual energy savings of 7.9% of rack and gas cooler energy use, equal to 35,395 kWh per year for that store.
That gives FTE a strong case for new stores and projects where year-round rack efficiency is a priority.
ETE Focuses on High-Ambient Performance
ETE stands for Extreme Temperature Efficiency. Its job is more focused on high-ambient operation.
ETE is a patented Epta Group technology developed to improve energy efficiency in standard CO2 transcritical systems under high ambient conditions. It works by reducing flash gas formation after the high-pressure valve via an embedded mechanical gas-cooling system within the CO2 transcritical booster system.
In warmer conditions, gas cooler outlet temperature can rise. ETE helps cool the gas leaving the main gas cooler before it enters the high-pressure valve. The ETE system uses a dedicated compressor and a heat exchanger installed after the main gas cooler. This cooling lowers the temperature of the gas entering the high-pressure valve, which results in a liquid-vapor mix with less vapor and more liquid available to feed display cases.
In simple terms, ETE helps the system keep more useful liquid refrigerant available when heat would normally make that harder.
For retailers in hot climates or stores with demanding high-ambient operating conditions, that can be a major advantage.
FTE Is Broad, ETE Is Targeted
FTE and ETE both support energy-efficient refrigeration systems, but they are not interchangeable.
FTE is about improving efficiency throughout the year by enhancing evaporator performance and raising the medium-temperature suction pressure. It can be especially compelling when the retailer wants measurable annual savings from a CO2 system and is planning the piping and system layout early enough to accommodate it.
ETE is about protecting efficiency under high ambient conditions by reducing flash gas and improving the quality of the refrigerant feeding the cases. It is especially relevant when hot weather performance is a primary concern.
Think of it this way:
- FTE helps the system work smarter across normal operation.
- ETE helps the system handle heat stress more effectively.
Some projects may call for one, while others may benefit from a deeper discussion about both. The right answer depends on climate, store design, energy goals, operating conditions, budget, and how the refrigeration system is being configured from the start.
Efficiency Choices Need Planning
Neither technology should be treated as a last-minute add-on.
The Highland Bridge project required separate medium-temperature and low-temperature liquid lines, and that specific store also required two separate groups of medium-temperature suction lines. That does not weaken the case for FTE, but simply shows why early planning matters.
The same is true for ETE. Since ETE includes components such as a dedicated compressor, heat exchanger, electronic expansion valve, motorized valves, sensors, pressure transducers, and control logic, it should be planned as part of the system strategy rather than tacked on after design decisions are already locked in.
Smart CO2 refrigeration design starts with the load, the climate, the store layout, and the operator’s goals. Then the technology conversation begins with a full understanding of the needs.
Better CO2 Efficiency Supports Better Stores
A grocery store refrigeration system has to do multiple jobs simultaneously:
- It has to protect product temperature.
- It has to support food quality.
- It has to run reliably.
- It has to help manage energy use.
- It has to fit into sustainability plans.
- It has to fit into your budget.
That is why FTE and ETE are worth discussing together.
They offer retailers various ways to improve CO2 transcritical performance without sacrificing the benefits of natural refrigerants. Together, FTE and ETE show how far CO2 refrigeration has moved from being a simple refrigerant choice to a full system-performance strategy.
Don’t choose a technology because it sounds impressive - the smart path is choosing the system approach that fits the store.
Kysor Warren works with retailers across supermarkets, convenience stores, foodservice, and mass-merchant environments to develop refrigeration solutions tailored to real operating needs. For stores considering CO2 natural commercial refrigeration, FTE and ETE give operators stronger options for efficiency, reliability, and long-term performance.
To explore the right CO2 refrigeration strategy for your store, connect with Kysor Warren and learn how FTE, ETE, and energy-efficient refrigeration systems can support your next project.