Walk-in coolers and freezers are natural places to look for energy efficiency gains in commercial refrigeration. Energy-efficient operation depends on more than individual components; it also requires the right application planning, system type, refrigeration components, connected controls, and awareness of changing energy and refrigerant standards.
This guide explains five key considerations for improving walk-in cooler and freezer performance: defining the intended use, selecting the right refrigeration system type, choosing efficient components, using connected controls, and preparing for energy and refrigerant regulations.
How can walk-in coolers and freezers operate more efficiently?
Walk-in cooler and freezer efficiency starts with matching the refrigeration system to the application. The system should be designed around the required temperature, humidity, airflow, product type, system layout, controls, and regulatory requirements.
Energy savings are achieved when the system is planned correctly, components are sized and selected for the application, and controls are used to manage temperature, defrost, fans, doors, lights, and alarms efficiently.
1. Establish the intended use of the walk-in cooler or freezer
The first consideration for an energy efficient walk-in cooler or freezer is understanding the purpose of the refrigeration system. Preparing the walk-in cooler or freezer for its intended use helps minimize inefficient heat waste and unnecessary cooling caused by poor planning.
A walk-in cooler or freezer may be used for general food storage, but some applications require more precise conditions. For example, restaurants may need specific humidity, temperature, or airflow requirements for applications such as beef curing or ice cream storage.
When defining the intended use, consider:
- product type
- required storage temperature
- humidity sensitivity
- airflow requirements
- frequency of door openings
- product loading patterns
- food safety requirements
- whether the application is chilled or frozen storage
2. Determine the right refrigeration system type
There are three common refrigeration system types used in walk-in coolers and freezers:
- self-contained refrigeration systems
- remote condensing unit systems
- supermarket parallel rack systems
Choosing the right system type is important because each system fits different installation requirements, space constraints, heat rejection needs, and application sizes.
Walk-in cooler and freezer system types
| System type | How it works | Best fit |
|---|---|---|
| Self-contained system | The evaporator and condenser are housed in one unit, similar to a window air conditioning unit. | Smaller walk-in coolers or freezers, leased spaces, locations where exterior penetration is not allowed, or installations where an outdoor condenser is not possible due to noise or cost constraints. |
| Remote condensing unit system | The condensing unit and evaporator are shipped as separate components. The evaporator is installed inside the walk-in, while the condensing unit is typically installed outdoors, on a rooftop, or adjacent to the building. | Hotels, restaurants, convenience stores, and applications where indoor space cannot accommodate heat rejection or where conditions are not suitable for efficient self-contained operation. |
| Supermarket parallel rack system | A centralized refrigeration system with multiple compressors and evaporators. | Supermarkets and larger food retail applications with multiple refrigerated spaces connected to a compressor rack. |
3. Choose efficient refrigeration components
Nothing has a greater impact on walk-in cooler or freezer performance than a properly sized and designed refrigeration system. A walk-in cooler or freezer system should be composed of components that efficiently transfer heat out of the space and help keep contents fresh or frozen.
The main components of a walk-in cooler or freezer refrigeration system include:
- compressor
- condenser
- metering device
- unit cooler
- thermostat or controller
- refrigerant
A lower-GWP refrigerant such as R448A may be used depending on the system and application requirements.
Core components in an efficient walk-in cooler or freezer system
| Component | Function in the system | Energy efficiency role |
|---|---|---|
| Compressor | Compresses and circulates refrigerant through the system. | Supports the cooling process and should be correctly matched to the system load. |
| Condenser / condensing unit | Rejects heat from the refrigeration system. | Efficient condensing units help maximize system performance and support system lifetime. |
| Expansion valve or metering device | Meters refrigerant into the evaporator based on system demand. | Proper refrigerant metering helps the system operate efficiently. |
| Unit cooler / evaporator | Removes heat from inside the walk-in cooler or freezer. | Helps control temperature and humidity inside the refrigerated space. |
| Electronic thermostat or controller | Controls temperature and coordinates system operation. | Integrates control of box temperature, evaporator fan, defrost heater, and condensing unit. |
| Refrigerant | Circulates through the system and changes state to move heat. | Refrigerant choice affects system design, performance, and regulatory readiness. |
Danfoss components for walk-in cooler and freezer efficiency
Danfoss provides components that support efficient walk-in cooler and freezer operation.
TU thermostatic expansion valve and ETS electric expansion valve
The Danfoss TU thermostatic expansion valve regulates refrigerant flow based on system needs and supports efficiency by maintaining tight superheat.
Danfoss ETS electric expansion valves are designed for precise liquid injection in evaporators
The valves are fully balanced and use a bipolar motor to provide precise flow regulation. ETS valves pair with EKE controllers and sensors.
Optyma™ Slim condensing unit
The Danfoss Optyma™ Slim condensing unit is designed with components that support efficiency, reliability, and ease of installation.
Optyma™ Cooler
The Danfoss Optyma™ Cooler is a compact and efficient unit cooler that supports refrigerant turbulence, high efficiency, and food safety.
Optyma™ Control
The Danfoss Optyma™ Control electronic temperature controller controls compressors, solenoid valves, defrost, second evaporator defrost, fans, lights, and crankcase heaters. It can improve room efficiency by up to 30%.
4. Use connected controls for monitoring and energy savings
Connected controls help manage walk-in cooler and freezer operation more efficiently. A smart controller system can manage several components from one device and support energy savings through control functions such as:
- adaptive defrost
- set point change mode
- door management
- door frame heater management
- light control
A connected walk-in cooler or freezer system can also help reduce the risk of food waste and energy waste. If the system goes down, connected monitoring can send alerts to a smart device, giving contractors or maintenance staff the opportunity to troubleshoot before inventory is wasted or costly repairs are required.
Connected systems can also use cloud-based platforms for performance monitoring, trending, food safety reporting, predictive maintenance, and energy optimization.
5. Understand energy standards and refrigerant regulations
Energy standards and refrigerant regulations affect walk-in cooler and freezer system design, especially systems using remote condensing units.
Annual Walk-in Efficiency Factor
The US Department of Energy uses the Annual Walk-in Efficiency Factor, or AWEF, as a metric for walk-in cooler and freezer efficiency. AWEF measures the ratio of heat removed from the cooler or freezer to the total energy input of the refrigeration system over one year.
Walk-in cooler and freezer components must be tested and must meet or exceed minimum efficiency requirements before installation.
A proposal has also been submitted to update testing procedures and determine whether a more stringent metric, AWEF2, can be achieved.
Natural Resources Canada requirements
For Canada, Natural Resources Canada requirements are nearly identical to AWEF. The difference stated in the guide is that NRCan requires certification by a third party, while AWEF allows self-certification.
AIM Act and HFC phasedown
The US Environmental Protection Agency’s American Innovation and Manufacturing Act includes a phasedown of the production and consumption of HFC refrigerants across the refrigeration industry by 85% over 15 years.
As HFC availability and cost change, the refrigeration industry is moving toward non-HFC alternatives with lower global warming potential.
SNAP Rule 20
Several US states have adopted the Clean Air Act’s Significant New Alternatives Policy Rule 20. This law prohibits HFCs in stationary refrigeration and air conditioning, including food retail refrigeration equipment such as R404A in remote condensing units.
Top 5 energy efficiency considerations for walk-in coolers and freezers
| Consideration | Why it matters |
|---|---|
| Establish the intended use | Helps avoid inefficient heat waste and unnecessary cooling caused by poor planning. |
| Determine the right system type | Ensures the refrigeration system matches the installation, application size, and heat rejection requirements. |
| Choose efficient components | Properly sized compressors, condensers, expansion valves, unit coolers, and controllers help improve system performance. |
| Use connected controls | Smart controls can manage defrost, doors, heaters, lights, alarms, and monitoring to support energy savings and reduce risk. |
| Understand energy and refrigerant standards | AWEF, NRCan requirements, the AIM Act, and SNAP rules affect system selection, refrigerant strategy, and long-term compliance. |
FAQ
Best condensing unit for a commercial walk-in freezer?
Select a low-temp unit with adequate BTU/hr for freezer load, e.g., Danfoss Optyma™ Plus for -10°F.
What is the AIM Act and how does it affect cold room refrigerants?
It mandates phasedown of HFCs in the US, pushing adoption of low-GWP alternatives.
What is the best way to improve walk-in cooler or freezer efficiency?
The best way to improve walk-in cooler or freezer efficiency is to match the system to the application, choose the right refrigeration system type, use properly sized components, add connected controls, and consider energy and refrigerant regulations during design or retrofit.
What's the best way to cut energy costs across multiple walk-in coolers in a supermarket — better controls, smarter defrost, or new equipment?
Install variable-speed compressors, optimize defrost schedules, and improve door sealing.
What are the main types of walk-in cooler and freezer refrigeration systems?
The three main types of walk-in cooler and freezer refrigeration systems are self-contained systems, remote condensing unit systems, and supermarket parallel rack systems.
When should I use a self-contained refrigeration system?
A self-contained system is best for smaller walk-in coolers or freezers, leased spaces, installations where the condenser cannot be placed outside, or locations where penetrating the building exterior is not allowed.
When should I use a remote condensing unit system?
A remote condensing unit system is commonly used when the evaporator is installed inside the walk-in cooler or freezer and the condensing unit is installed outdoors, on a rooftop, or adjacent to the building. This system type is widely used in hotels, restaurants, and convenience stores.
What components are used in a walk-in cooler or freezer refrigeration system?
A walk-in cooler or freezer refrigeration system typically includes a compressor, condenser or condensing unit, metering device, unit cooler or evaporator, thermostat or controller, and refrigerant.
What monitoring system can alert me if a walk-in cooler temperature goes out of range?
Use a remote monitoring system with SMS/email alerts, e.g., Danfoss AKC series.
Why is an expansion valve important in a walk-in cooler or freezer?
An expansion valve meters the correct amount of refrigerant based on evaporator demand. A properly set expansion valve helps the walk-in cooler or freezer operate efficiently.
What controller should I use for a commercial walk-in cooler?
Use an electronic controller with temperature, defrost, and alarm functions, e.g., Danfoss ERC series.
How do connected controls support energy savings?
Connected controls support energy savings by managing functions such as adaptive defrost, set point changes, door management, door frame heater management, and light control. They can also support monitoring, alerts, food safety reporting, and energy optimization.
Energy-efficient refrigeration for grocery store walk-in coolers?
Use high-efficiency compressors, EC fans, LED lighting, and demand-based defrost cycles. Utilize floating head pressure if condensers are outside.
What is AWEF?
AWEF stands for Annual Walk-in Efficiency Factor. It measures the ratio of heat removed from the cooler or freezer to the total energy input of the refrigeration system over one year.
How does the AIM Act affect refrigeration?
The AIM Act includes a phasedown of HFC refrigerant production and consumption across the refrigeration industry by 85% over 15 years. This affects refrigerant availability, cost, and the move toward lower-GWP alternatives.
What should I consider when building or retrofitting a walk-in cooler or freezer?
When building or retrofitting a walk-in cooler or freezer, consider the intended use, system type, component selection, connected controls, energy efficiency standards, refrigerant regulations, and long-term service needs.
What energy efficiency standards apply to commercial refrigeration in the US?
Per 10 CFR Part 431 — Energy Efficiency Standards for Commercial Refrigeration Equipment:
DOE mandates minimum efficiency levels for walk-in cooler/freezer doors, panels, refrigeration systems, and lighting.
Examples:
- Maximum energy consumption ≤ 0.4 kWh/day per square foot for certain cooler doors.
- High-efficiency fan motors (ECM or equivalent).
- Minimum insulation R-values for panels.
Compliance is verified through DOE-approved testing procedures.
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