The display refrigeration equipment in grocery shops, convenience stores, and restaurants will typically account for 25% to 60% of the electricity used. Modern equipment has seen many advances in refrigeration technology which are both cost effective and improve product quality.
The size and type of your business will determine the type of refrigeration equipment used.
Central refrigeration systems consist of refrigerated spaces connected to a remote condenser. These systems have the advantage of emitting waste heat outside of the conditioned space through the condenser.
Stand-alone refrigeration systems, often called merchandisers, usually have the case, evaporator and condenser packaged in a single unit, similar to a home refrigerator. These stand-alone units are commonly used in smaller facilities where a central refrigeration system is not justified.
There are many tips to consider when maintaining your equipment but the most common advice is to clean cooling coils regularly to ensure proper airflow and heat transfer.
The US website http://fpl.bizenergyadvisor.com/grocery-stores states that energy costs account for 15% of a grocery store’s operating budget.
Because grocery stores’ profit margins are so thin, approximately 1%, every £1.00 in energy savings is equivalent to increasing sales by £59.00.
If refrigeration comprises 50 % or more of the electricity costs for grocery and convenience stores it is likely that lighting will account for 20% whilst cooling and ventilation both average about 13 %. Any energy saving strategy that reduces these costs will increase floor space profitability and improve the operating margins of your business.
In “A Cool Display” published in the March 14 copy of The Grocery Trader we stated that: “Thermal Engineering suggests that the UK’s retail food outlets are responsible for approximately 3% of total electrical energy consumption. Refrigeration accounts for a major percentage of in-store electricity demand ranging from 25% – 30% for larger hypermarkets to over 60% for food-dominant convenience stores. The report concludes that if those stores with above average energy usage reduced their consumption to industry-wide average levels through implementing energy conservation measures, then an additional 10% electrical energy savings could be achieved. This represents around 840 GWh of electricity and a reduction of 355,000 tonnes of CO2 emissions if applied to all the stores of the major retail food chains in the UK”.
Obviously, grocery and convenience stores have long hours of operation and are open most days of the week. Some equipment is on and running constantly even when the store is closed. Energy costs can add up even more when equipment is old and inefficient.
During a recent visit to a factory in Stoke we were able to view new display refrigeration cabinets using the latest technology to reduce the energy consumed. This company also refurbish old units and we saw many that had been returned for repair (see figure 1).
Typically the reason for system failure was caused by the clogged or compacted coils which increase the head pressure and cause the compressor motors to fail (see figure 2). Although this repair can be completed by a competent mobile service engineer many of the major retailers simply remove the unit for offsite repair so that the floor space can continue working with a replacement.
In all air movement equipment it is imperative that the resistance is kept at a minimum. On large air handlers you will typically have a pre-filter followed by secondary and even tertiary filters depending upon the application.
In refrigeration equipment, including remote condensers, the coils are unprotected and so all airborne debris is drawn into the coil section and lodges between the fins.
1mm of dirt will cause a 21% drop in efficiency and can increase refrigeration energy use by 35%.
Clean equipment runs more efficiently and so condenser and evaporative coils need to be kept as clean as possible.
That is why the use of a PreVent Equipment Filter (see figure 3) is slowly being recognised by the food industry as a cost effective upgrade to existing and new equipment. The filter sits on the outside of the air intake louvre which allows retail staff to remove and clean them as part of their daily cleaning schedule.
There are approximately 800,000 retail display units running in the UK with more being added everyday as the number of convenience stores grow. There is a lot of energy to be saved if these units can be kept running as efficiently as possible which equates to more profit for the retailers.
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