Open with care

The energy-saving benefits of doors on chillers are well documented: up to 40% with a retrofit and a whopping 60% reduction possible if old open cases are replaced with new door cabinets and plant.

Take independent retailer Jatinder Sahota, for example. He’s already saving £300 a month following the installation of new Delta Total Vision acrylic door multidecks, and an update of the store’s existing Delta & Arneg multidecks with Total Vision doors just seven months ago. The change, which was carried out as part of a significant store refurbishment, also saw him double the amount of refrigeration - yet despite this extra capacity his first energy bill in March 2015 showed “no increase at all.”

With case studies like that it’s hardly surprising then that about 45% of convenience stores are now thought to feature doors on some, or all of their chillers (ACS Local Shops Report 2014), or that a growing number of retailers are planning to invest in new chillers with doors or retrofit projects in 2015 and beyond.

However, before they do, retailers should take note of this important warning: doors do not always represent an open and shut case for slashing energy bills.

While the right type of door, in the right type of store, fitted by a reputable supplier and maintained properly, can result in significant savings, those retailers who get this complex mix wrong risk not only closing the door on energy reduction, but could alienate customers and even lose sales.

A store’s location and footfall, for example, can have a direct impact on just how significant any energy savings can be.

Ian Wood, managing director of Adande Refrigeration, explains: “Obviously, as physical barriers doors will prevent the spillage of cold air from refrigerated cabinets when the doors are closed. However, doors are a less-effective solution in high-traffic stores with frequent door openings.

“The frequency and duration of door openings, particularly in high-traffic convenience stores with a large proportion of chilled sales, are the determining factors in the efficiency of glass doors in reducing energy consumption.”

The Carbon Trust draws a similar conclusion in its Refrigeration Road Map report, produced with the Institute of Refrigeration and British Refrigeration Association. “Cabinets with doors undergoing higher usage have been shown to save little energy when compared with an open-fronted cabinet,” it says.

In fact, a 2011 report from the European Partnership for Energy and the Environment and industry association Eurovent asserts that once a frequency of 60 door openings per hour is exceeded then there is no advantage in fitting cabinets with doors.

Savings can also be directly affected by the type of door that you choose. The door itself can be made of acrylic or glass, and have single, double, and triple glazing.

There are pros and cons for each, as Simon Robinson, managing director of Delta Refrigeration, explains: “There are now many options to choose from. Acrylic double-glazed offer the best solution for vision and usability as they are light and open 60 degrees to merchandise. Double-glazed glass doors are a good-value solution, but are heavier so make sure that the installer is reputable and can make sure the cabinet can take the extra weight as some cases could tip forward,” he says.

Stuart Johnson, retail controller at Landmark Wholesale, also has a few words of warning: “Glass can be prone to condensation as well as there being the potential of shattering. Acrylic, meanwhile, has the potential to be scratched and marked.”

Condensation, as Johnson mentions, can be an issue for some glass doors, and it’s not one to be taken lightly. Condensation not only prevents shoppers from being able to view products properly, but can also create a bad impression - doors dripping with condensation don’t exactly shout freshness.

Serge Kremer, owner and chief executive of Husky.co.uk, explains: “Condensation happens when there is a difference in temperature. So when fridge doors are opened and closed, any water or moisture in the air that touches a cold surface (such as the fridge doors) will cause droplets to appear on the glass. “There are, however, ways to deal with this problem. With glass doors you need to redirect the heat generated by the fridge and create a forced air curtain, pushing the hot air up in front of the glass. A thicker glass will mean there is less chance of condensation.”

Anti-sweat heaters (ASHs) can also be used to help reduce, or stop, condensation forming on glass door cabinets. These work by heating the glass doors to prevent condensation. Controls can also be used to reduce or turn off ASHs based on the amount of condensation formed on the door.

Alternatively, they can sense the relative humidity in the air outside of the display case and reduce or turn off the glass door and frame ASHs in response to the level of humidity in the store.

There are also doors available that prevent condensation from occurring within the frame assembly.

Helpful extras

Other fixtures and fittings to look out for when purchasing doors for a retrofit or new cabinets are reflective low E glass and spring-loaded doors for self-closing, Kremer adds.

Low E coatings will minimize the amount of ultraviolet and infrared light that can pass through glass without compromising the amount of visible light that is transmitted, while spring-loaded doors will ensure that cabinets close should shoppers or staff forget.

How the doors open (sliding or hinged) is also thought to have an impact on energy efficiency. A recent study by the Institute of Refrigeration states that during opening and closing, hinged doors push in about 17% more warm outside air than sliding doors - potentially making them slightly less energy efficient. “This would seem logical as hinged doors tend to drag air from the cabinet when opened and push air into the cabinet when closing. Sliding doors have less impact on the cabinet air curtain and therefore would be expected to have lower infiltration (warm air entering a chiller) during door openings,” it said.

However, the study also notes that sliding doors are more difficult to seal than hinged and could therefore be more susceptible to infiltration when closed.

Ultimately, the final decision on whether to opt for slide or hinge opening should probably be cast with your store layout in mind. Sliding doors are more practical in small stores or narrow aisles so as not to cause congestion.

Johnson at Landmark Wholesale elaborates: “There are a number of store layouts where chillers with doors wouldn’t work well,” he says .

“Opening and closing chiller doors limits the number of people that can shop the cabinet at any given time and if one customer is standing with a door held open, they create a barrier to other shoppers.

“I would suggest that retailers should carefully consider which cabinets should have doors and which should not,” he adds.

It’s also important to note that fitting doors alone will not always result in the significant energy savings you had hoped for. “Unless the refrigerated equipment is re-commissioned and the cabinet temperatures are adjusted the plant will still run too much and that is where the bulk of the electricity is being used,” Delta’s Robinson adds.

Tony Wright, divisional director at energy efficient fan and motor manufacturer ebm-papst, agrees: “Upgrading the fans and fan motors in refrigeration systems can provide substantial energy and financial savings,” he says. “Many chiller cabinets still work with conventional shaded-pole motors, consuming considerable energy. There are energy-saving motors that have an efficiency of more than 70% and require only about a tenth of the power, so installing these motors in refrigeration systems can result in substantial savings for convenience stores,” he adds.

And there are, of course, a growing number of compelling alternatives to chiller doors. Adande’s Aircell system is one example. The air-flow management system segments chiller cabinets into a series of air-flow managed cells with shorter air curtains which reduce cold air spillage - resulting in energy savings of up to 30%, according to the company.

The product is enjoying growing popularity in the retail space and is already used by a number of Tesco supermarkets.

“The traction is being driven by retail merchandisers, who are concerned that glass doors act as physical barriers, discouraging browsing and reducing sales,” Adande’s Wood says.

The capital cost of incorporating Aircell within a retail refrigerated cabinet is comparable to that of fitting doors. However, Wood adds: “When cleaning and maintenance are taken into account, Aircell is more cost effective than glass doors in terms of life cycle investment.”

Enviroglow’s ChillScoop and Aerofoil technology is another interesting solution, and one which a number of retailers including members of Premier, Costcutter and Bargain Booze are turning to.

The two technologies work together to scoop up and retain the cold air from inside the chiller without creating a physical barrier between shoppers and the product. Energy savings can be as high as 43% on existing open-deck chiller consumption, according to Enviroglow.

No barriers

Premier Whitstone Stores owner Dan Cocks, from Holsworthy in Devon, is saving about £150 a month on his refrigeration costs since having ChillScoops fitted. “I recently attended an ACS study tour and all five of the stores we visited featured chillers with doors. While there is no denying that doors can look really stunning, there is also no denying that they are more expensive to fit, and the savings that I have achieved with scoops are almost, if not as good,” he says.

While doors on chillers cost on average between £700 and £1,200 per metre, ChillScoops and Aerofoil cost £240 per metre and up.

Other benefits besides energy reduction include next to no wear and tear, as unlike doors with hinges, scoops have no moving parts. There is also little extra cleaning required - unlike doors which need to be kept clean and smudge-free so as not to deter shoppers. The regular cleaning of doors does, of course, necessitate a bit of extra work. But as Londis retailer Roli Ranger attests: “It shouldn’t be too onerous if you already have high standards of cleanliness and good disciplines in place.”

Roli recently decided to fit double-glazed acrylic doors on all of the chillers at his new Londis store in Sunninghill, Berkshire.

“I chose acrylic as it is much lighter than glass to open and close. The large cut-out handles add to this ease of opening and closing, and I’m expecting to save about 30% on my refrigeration costs,” he says.

He was swayed not just by the promise of energy reductions, but also by the litany of other benefits that doors on chillers are thought to offer, such as warmer aisles, lower heating bills and reduced shrinkage. Roli is also a firm believer that the combination of doors on chillers and LEDs improves product appearance, particularly that of fresh produce.

And he’s a firm believer that doors do not act as a barrier to sales. “That might have been true a few years ago, but shoppers are used to seeing doors now. If anything I would say that they can boost sales as I think products look even better than before. The doors look smart and boost the perception of freshness and quality,” he adds.

Doors have also helped Surrey retailer Dean Holborn reduce shoplifting. New glass door multidecks from Delta were fitted as part of his recent Redhill store development and Dean says that he has noticed a “vast reduction in theft from the BWS chillers”.

“It’s now a two-handed operation to steal bottles and cans, which is deterring people from trying to steal,” he explains.

“Since the store was refitted, my weekly store takings have increased on average by 18%. Although this cannot be directly attributed to just the refrigeration it’s still a good indicator as to how the new cabinets have contributed towards a successful and profitable store refit,” he adds.

Vic Grewal of Simply Fresh in Thames Ditton, Surrey, agrees: “I would never open a new store or embark on a refit without having doors on chillers,” he says. “The right doors for your store make it warmer and the energy savings are undeniable. Another fringe benefit is that they stop dust and dirt from the road outside from getting in and covering your shelves and products.”

“The question for most convenience retailers is no longer ‘Do I fit doors or not?’. It’s ‘Which type and where?,” he adds.