No Closure in the Debate on Doors for Refrigerated Display Cases

October 13, 2019

 A petition calling for open front refrigerated display equipment to be banned in UK supermarkets has once again brought to the fore the issue of retailers’ energy usage and the need for measures to reduce their demand for electricity. The motion, tabled by Dr Jonathan Golding, was posted on the UK Parliament e-petitions’ website in June and by the first week of August it had received over 27,700 signatures. Should the number of signatories reach 100,000 the petition will be considered for debate in Parliament. The flames have been further fanned by a raft of related articles in regional and national newspapers. Applied Design & Engineering’s Managing Director, Ian Wood, has voiced the company’s support for the campaign to reduce the food retailing industry’s energy consumption, pointing out that there is more than one way to achieve this objective.

For decades retailers and shoppers have preferred the open front multi deck cabinet as the solution for the display of chilled goods. It provides high visibility of merchandise, as well as free and unfettered access for browsing, shopping and restocking. The main problem associated with conventional open front chillers is that dense cold air spills from the cabinet into the store aisle. This factor, combined with warm air infiltration, means that greater duty is placed on the refrigeration plant to maintain operating temperature, resulting in increased energy consumption.

Equipment manufacturers and grocery retailers have been working together to address cold air spillage and several solutions have been developed. Some retailers are retrofitting shelf edge technology to cabinets, but this solution does not deliver the level of energy savings which will be required to make a significant impact on the retail industry’s electricity consumption, nor does it address the issue of accurate holding temperatures for food quality and safety. A number of manufacturers, retailers and lobby groups have latched onto hinged or sliding doors as a panacea, but the fact that they have not been widely adopted in supermarkets suggests that doors are not always the best solution, especially in high footfall stores. Although used elsewhere in the world, plastic strip curtains are seldom used in the UK.

Applied Design & Engineering has adopted a more radical approach to the problem of cold air spillage with the development Aircell®, which has been designed to be incorporated within newly built equipment. It works by dividing the refrigerated display case’s merchandising envelope into separate air flow managed cells with low pressure air columns. Each cell has its own air curtain, which is more efficient than a full case height air curtain on a conventional multi deck case. The net result is less pressure on the air curtain of each cell and a substantial reduction in cold air spillage, creating energy savings of over 30% compared with conventional open front cabinets. Aircell® also maintains accurate operating temperatures, within a tighter bandwidth, to keep food at optimum appearance, safety and quality over extended periods. All this is achieved whilst maintaining the preferred open front format.

Whilst doors may be an effective solution for low footfall stores with infrequent door openings, there is evidence to suggest that they are not so effective in busy supermarkets and convenience stores. The industry standard for the testing of refrigerated retail display cabinets, BS EN ISO 23953, states that tests on cabinets with glass doors should be conducted with 10 door openings per hour (every six minutes) with an opening/closing cycle of 15 seconds, but Orlandi et al (2013) claimed that the figure can reach 60 per hour in supermarkets and in 2011 EPEE and EUROVENT stated that some food retailers have registered up to 250 door openings per hour.

To investigate the impact of frequent door openings, Adande has conducted laboratory trials under BS EN ISO 23953 conditions. During 7 day testing, temperatures within a cabinet with doors were measured, during 12 hour periods at 30 second intervals, for various opening frequencies with opening/closing cycle of 15 seconds. Having established baseline data for door openings of 10 per hour, tests were conducted at 30 openings per hour. The results demonstrated that the average test pack temperature rose by 5°C and the bandwidth was recorded at 8.5°C. The cabinet failed to recover to the operating temperature of -1 to +4°C, even after twelve hours with the doors closed. The increased temperature in the cabinet increased the duty on the refrigeration plant with a consequent surge in energy consumption.

Ian Wood, explained:

“Understandably, many OEMs have engineered glass door cabinets to meet the BS EN ISO 23953 specification of 10 door openings per hour. However, the evaporators specified are not capable of dealing with the higher infiltration loads associated with more frequent door openings. This results in iced evaporators and a loss of temperature control or more frequent and harsher defrost cycles with increased energy consumption. Our tests clearly demonstrate that glass doors cabinets, designed for 10 openings per hour, experience significant loss of temperature control at an opening frequency of 30 openings per hour or more.”

Doors on cabinets are regarded by some as visual and physical barriers to shoppers, acting as deterrent to browsing and impulse purchases. There are also cleaning and maintenance costs associated with doors, which add to retailers’ overheads. Furthermore, in the grab & go sector, where stores are typically smaller and operators depend on the high visibility of merchandise and fast service, doors are a wholly impractical solution.

Ian Wood added that the issue of doors is just the tip of the iceberg when it comes to the overall debate on supermarket refrigeration:

“Refrigeration is a key element of the food chain, maintaining food at optimum quality and appearance. As an industry, we need to be developing technology, which demonstrates more accurate and stable holding temperatures, for longer product shelf life and a reduction in food wastage, which has become a major issue for environmental campaign groups.”

There are other factors, which are going to drive the development of more efficient refrigerated displays, with more accurate and stable temperatures. Pressure on retailers to limit or eliminate the use of plastic packaging is having a negative impact on the quality, safety and shelf life of perishable goods. Similarly, the health lobby is continuing to push for a reduction in food additives, including salt and sugar, which will also compromise the longevity of foodstuffs, unless stored and held at accurate and stable temperatures.

Forthcoming Ecodesign regulations will see the introduction of compulsory labelling on retail refrigerated displays, making the energy efficiency of such equipment more transparent and manufacturers more accountable. However, it seems unlikely that these regulations will call for doors on supermarket refrigeration equipment. In response to the public petition and recent press coverage, the Department for Business, Energy and Industrial Strategy (BEIS) maintains that the government is taking action to implement energy saving initiatives, but is not necessarily advocating the use of doors. It stated: 

“Our minimum performance standards remove inefficient products from the market and labelling raises awareness of the best ones. Minimum energy performance standards, otherwise known as Ecodesign regulations, are technology neutral so do not prescribe that manufacturers should increase efficiency by putting doors on appliances. Rather they set a minimum energy efficiency limit that all manufacturers placing products on the market must meet.”

Ian Wood believes that the current debate on supermarket display equipment offers considerable opportunities for the UK refrigeration industry:

“The holy grail for retailers is an open front cabinet for high visibility of merchandise and ease of browsing and shopping, combined with significant energy savings and accurate and stable temperature control. Cabinets with doors do not meet these criteria and shelf edge technology does not deliver sufficient energy savings or meet the needs for accurate control of operating temperature. In my opinion the only technology, currently available, which fits the bill Is the Aircell® air management system. We will continue to support the drive for the development of disruptive technology, which lowers energy consumption and reduces food waste.”

For further information ontact: Applied Design & Engineering Limited, 45 Pinbush Road, South Lowestoft Industrial Estate, Lowestoft, Suffolk NR33 7NL, UK

Tel: + 44 (0) 844 376 0023     Fax:  + 44 (0) 1502 533794

Email: info@adande.com   www.adandeaircell.com

 

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