Constantly restocking your chilled displays with room temperature cans, bottles and snacks means they have to work harder to bring them down to sales temperature, and this creates warm air, which heats your aisles. That makes it harder to cool the drinks... so you have the perfect cycle of rising temperatures and spiralling energy bills.
Last month Londis retailer Ramesh Shingadia told C-Store how two of his refrigerated cabinets had broken down, unable to cope with July's soaring temperatures. As well as risking disappointing his customers, he lost his frozen stock and had to put in an emergency call to an engineer to come and fix the problem. "Drinks and chilled snacks need to be at the front of the shop, but when the shop door is open hot air is constantly coming through and the compressor has to work extra hard to keep food and drink cool," he says. Unfortunately, that extra work was not only wearing out components it would have had the electricity meter spinning as well.
"Refrigeration is the largest energy load in your store, and at about 2,000 kWh for every square metre of sales area, it accounts for nearly 60% of your electricity consumption," says Judith Evans of Refrigeration Developments and Testing (RD&T), a company which advises on the design of refrigerated cabinets.
"The equipment you use is crucial to keeping costs under control. You need to make sure you buy the best cabinet in the first place, that you use it correctly and look after it, and that the environment in your store gives it a fair chance to do its job efficiently."
As any c-store retailer knows, the cheapest option is not always the best. This is just as true with your own purchase decisions with store equipment it's essential to consider not only the initial capital cost, but the lifetime running costs of the unit.
An open chilled display might seem an obvious option, but consider this. "A chilled multi-deck costs far more to run than a cabinet with a glass door, but it is on average about 2.5m long whereas a single-door cabinet is usually 1m," says Evans. "But using three glass door cabinets would on average cost £720 a year to run against £1,439 for a multi-deck half the price.
"Over the average nine-year life of a cabinet the energy saving is £6,471." So the investment is certainly worthwhile.
l 72% of convenience shoppers buy beer and cider from the chiller l 80% of chilled drinks are consumed within two hours of purchase l 75% of lager drinkers say they would pay more for a chilled drink l Only 10% of supermarkets offer cold beer l The optimum temperature for beer is 4°C on 60% of occasions shoppers say it's not cold enough l Overchilling by 1°C add 2% to your power consumption.
"The best temperature classification for most drinks is likely to be what is termed M2 (from -1 to 7°C), so look on the manufacturers' brochure for a cabinet termed 3M2 which is the climate class and temperature performance," Evans adds.
"Ask if the cabinet has ECA (Enhanced Capital Allowance) accreditation. This means the cabinet meets certain temperature and energy requirements and its performance has been independently checked."
ECA approval means you can also claim a capital allowance which has a small financial benefit, but a far bigger win is in the energy you will save. A list of ECA-accredited equipment can be found at www.eca.gov.uk.
Geoff Smyth of the Carbon Trust recommends buying the best: "While improved shop-keeping will yield good energy savings, it also makes sense to spend to save even more particularly if you can use a Carbon Trust interest-free Energy Efficiency Loan," he says.
"We recommend projects that pay back in less than three years, but some will give a return within a year."
With the price of electricity likely to climb again, now is a good time to look at what you can do to prevent overloads and keep bills as reasonable as you can.
Regular checks will cut energy use and prevent leakage of environmentally nasty refrigerants, something which can earn you a hefty fine as well as reduce the efficiency of your equipment. Energy use goes up by as much as 15% when the charge becomes critically low, and losing gas will cause damage to the cooling system, which will eventually break down.
"Ideally, your cabinet needs a yearly MOT," Evans says. "Although this does cost money it can save energy as the callout charge of a good refrigeration engineer is substantially less than the cost of using 15% more energy. You can also carry out some maintenance yourself. By keeping the condenser clean and making sure the air grilles are clear you can make sure your cabinet operates as it should."
Get an engineer to regularly clean condensers and evaporators, replace split door gaskets and seals, and check for leaks. Dirt and debris can build up on heat exchanger surfaces and can have a dramatic effect on heat transfer if not removed.
How hot is your store?
Most cabinets in small stores are integral 'plug in' units where all the heat extracted is discharged by fans into the store. This is the last thing you need on a hot day, although it might be useful and save heating costs in winter.
Tests carried out by RD&T show that cabinets operated in an ambient temperature of 30°C can use double the energy of those at 25°C. Even if this went on for just a few months it could raise energy costs by almost £1,500 a year. On top of that, neither your customers nor your chocolate bars are going to be too happy in that kind of temperature.
So you could consider installing air conditioning in the store, but this also requires energy to operate. Another alternative is to operate the cabinets using an external refrigeration plant, so that all the heat from the refrigeration system can be disposed of outside the store. An installation like this requires a total change to the store and new cabinets, so would be part of a major refurbishment.
A more ambitious step would be to go for something like the Daikin Conveni-pack which provides heating, cooling and refrigeration using heat recovery a system which the manufacturer claims can reduce annual energy consumption by up to 50%. The purchase and installation costs of this are eye-watering for a small business, however.
In small stores with just a few cabinets, integral units are likely to remain the economic choice but don't forget to follow the siting and operating advice offered in the panel (right)
l Cabinets near natural lighting perform worse due to radiation, and cabinets near the street are affected by outside temperatures, humidity, dust and wind. Air from an air-conditioning unit can interfere with the air curtain of some open refrigerated cabinets. RD&T has found that drafts disturbing this air curtain can almost double the energy used.
l Make sure to use a night blind Used for 12 hours a day, these can save 20-25% of the energy, equating to £288 per year on an average cabinet. If not already fitted, they are relatively cheap to buy.
l Make sure that the cabinet is loaded correctly. Most open displays have an air curtain that runs from the top of the cabinet to the base at the front of the shelves. If this becomes disrupted by either cans, promotional posters or shelf-edge labels, air from the store can be pulled through the curtain.
This warm air then has to be cooled by the cabinet, raising the energy used. Do not place cans or packs on the air grille at the base of the multi-deck cabinets as this will block the cabinet air flow and increase energy use.
l Load to the front of each shelf. This helps to maintain the cabinet air curtain. If there are large gaps on shelves the air curtain tends to be drawn into the cabinet and brings in warmer air, which raises energy used.
l Consider keeping drinks chilled in the store room. It's far more efficient to use a small cold store or even a catering fridge to do the cooling, then put them pre-chilled into your shop floor cabinets which simply maintain that temperature. This will extend the lifetime of the display cabinets, too.
Source: RD&T (firstname.lastname@example.org.)