Door openings in real store trials far exceed those used in energy calculations for enclosed cabinet, making it ‘wholly impractical solution’ for high-traffic stores
Open deck technology specialist Applied Design & Engineering has weighed into the debate on doors on fridges, in the wake of the petition currently before the UK Parliament.
The petition calling for open front refrigerated display equipment to be banned in UK supermarkets has now received close to 28,000 signatures, and has triggered an official response from government department BEIS (see related story below)
AD&E’s managing director, Ian Wood, voiced support for the campaign to reduce the food retailing industry’s energy consumption, but pointed out that there is more than one way to achieve this objective.
He noted that while 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’.
He said that 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 with an opening/closing cycle of 15 seconds, but studies of real-store openings found that the figure can reach 60 per hour in supermarkets. In 2011, EPEE and Eurovent stated that some food retailers have registered up to 250 door openings per hour.
AD&E has conducted its own laboratory tests on the impact of door openings on energy and temperature in the cases.
During seven-day testing, temperatures within a cabinet with doors were measured,during 12 hour periods at 30 second intervals for various opening frequencies with an opening/closing cycle of 15 seconds. When tests were conducted at 30 openings per hour, the average test pack temperature rose by 5 deg C and the bandwidth was recorded at 8.5 deg C. The cabinet failed to recover to the operating temperature of -1 to +4 deg C, even after 12 hours with the doors closed, the firm found.
Significantly, the increased temperature in the cabinet increased the duty on the refrigeration plant with a consequent surge in energy consumption.
Ian Wood said: “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.”
The company noted that some retailers are retrofitting shelf edge technology to cabinets, but claimed ’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.’
The firm contended: ”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.”
AD&E has developed its own solution, called Aircell, for new cabinets, which works by dividing the refrigerated display case 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 firm says. ”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 per cent compared with conventional open front cabinets.”
The company went on to note that 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.’
The firm warned: ”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.”
Ian Wood concluded:“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.”