The food retail industry is one of the biggest global contributors of carbon emissions driving climate change. Grocery stores are incredibly energy-intensive operations, averaging 50 kWh per square foot per year, with small markets and convenience stores using almost double this amount. Almost 90% of this energy use is attributed to refrigeration, HVAC and lighting.
While energy consumption alone produces over 1300 metric tonnes a year for the average grocery store in the US, the Environmental Protection Agency (EPA) also reports an average of 1,500 metric tonnes of CO2 equivalents due to refrigerant leaks. With about 38,000 supermarkets in the US, this results in at least 112 million metric tonnes in direct emissions, not including indirect impacts such as food waste sent to landfills.
Hotter Summers Leading to Increased Energy Demand
With this multitude of factors, the realization of rising temperatures is putting traditional HVAC and refrigeration (HVACR) systems at risk. A 2°C (3.6°F) increase in average summer temperature raises refrigeration energy demand by 6%. During the 2018 UK heatwave, researchers from Imperial College surveyed energy usage at stores of a major supermarket chain.
They found that the HVACR equipment was being used more heavily, needing 5-11% more energy than the previous summer. They also saw an influx in complete breakdowns of refrigerated units, leading to rising costs for energy and maintenance services. This also greatly increased the potential for food waste if the product was not removed from failing coolers and freezers swiftly. These types of unusually warm days are expected to continue in parts of the UK and across the northern hemisphere.
Refrigeration Remedies for Hot Temperatures
To battle rising summer temperatures, experts have several suggestions, ranging from simple fixes to equipment upgrades and overhauls. Extensive maintenance of refrigeration units should be performed before hot summer temperatures set in, and preparations made for expedited repairs during the summer months. Some simple but significant enhancements that are recommended include installing doors or utilizing night blinds on refrigerated cabinets to keep cool air contained and warm air out.
Refrigeration in Traditionally Warm Climate Regions
For many areas of the world, extremely hot outdoor temperatures are nothing new. Refrigeration systems in warm climatic regions have long required innovative solutions to maintain efficiency and keep food cool as ambient temperatures rise. While these strategies are mostly borne out of necessity due to immediate high temperatures, they can also have a lasting impact on the efforts to curb climate change and reach net zero.
To reduce the high level of carbon emissions, a move to natural refrigerants is recommended. The eventual phasing out of hydrofluorocarbons (HFC’s) will vastly reduce the carbon footprint of supermarkets. Alternative refrigerants such as carbon dioxide (R744), ammonia (NH3) and propane (R290) have low global warming potential (GWP) and could all but eliminate the portion of emissions due to refrigerant leaks.
CO2 has emerged as the most popular alternative for large-scale refrigeration. The number of installations globally is growing rapidly and it is expected to become the industry standard. A transcritical CO2 system can have challenges in warmer weather, but certain system designs and equipment allow for efficient use of the refrigerant even as outdoor temperatures rise. These include the use of adiabatic coolers, parallel compression, ejectors, and sub-cooling.
For areas with even higher ambient temperatures, a cascade system may be preferred. Cascade systems combine a CO2 loop with an HFC refrigerant loop, resulting in reduced HFC charge and significantly lower carbon emissions. However, these systems introduce a level of complexity and can be costly for smaller operations.
The Relevance and Flexibility of RDM Controls
Taking into account all of these strategies and system architectures, an advanced and flexible controls system can help stores combine various approaches to different equipment into one central dashboard. The RDM line of controllers and its IP networked system provides tools to accomplish all the wide-ranging suggested best practices for refrigeration in extremely warm climates.
The following simple suggestions can be implemented efficiently and maintained using the RDM system. Robust energy-saving software features are available on the system front-end DMTouch, including a check for night-blind deployment, case performance monitoring, and trim (anti-sweat) door heater control. Other energy savings can be achieved through features such as Case off with Lights, turning off or reducing refrigeration for cases with non-perishable foods such as beverages when stores are closed.
The system can also play an important role in the crucial aspect of equipment maintenance. Remote visibility, performance monitoring, and alarm forwarding allow for predictive maintenance, the practice of vigilant monitoring where potential issues can be spotted early, saving on maintenance costs and leading to increased efficiency. Additionally, the remote monitoring service ActiveFM™ helps facility managers keep track of hundreds of sites via an online dashboard, with the option of using the 24/7 RDM Monitoring Team to notify store staff of critical alarms.
More advanced solutions are supported by the RDM system as well. The Intuitive Transcritical Superpack controller features complex parameter-based control strategies for CO2 systems, including support for technology like parallel compression. Sub-cooling can be operated with the Plate Heat Exchanger controller. Temperature and pressure control of refrigerated units is performed by Mercury controllers, and any other custom control needs can be accomplished with Intuitive or Mini Intuitive TDB controllers, RDM’s PLC platform featuring free programming software.
Energy Efficiency Benefits Everyone
As the threat of climate change becomes more real and immediate, food retail, cold storage, and similar facilities must adapt to changing temperatures. Energy-saving strategies not only help the efficiency and performance of equipment in warm climates, they also significantly lower operating costs. The RDM control system can manage the innovative strategies required in warm climates, while also providing additional energy savings that will benefit store owners, staff, patrons, and the environment alike.
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