SIGNIFICANT savings in electricity costs were achieved during the first 48 days of new Daikin Conveni-pack combined refrigeration, air conditioning and heating technology, applied to a Co-op Welcome convenience store in Sneinton Dale, Notts.
The savings were made in comparison with the running costs of the store’s previous conventional system during the same period in 2005.
From the middle of August, weekly electrical consumption has been a steady 5000kWh/week compared with 6000kWh/week last year.
It is significant that during the monitored period, which included three weeks of this summer’s higher than average ambient temperatures, no cabinet breakdowns or head pressure problems were recorded.
With lower ambient temperatures anticipated in the autumn and winter seasons, figures for in-store electrical consumption are expected to improve still further.
The sales floor of the Sneinton Dale store occupies approximately 23m x 12m with warehouse, office, kitchen and cooking area forming an L-shape at the rear and leading into the goods delivery yard. Chilled sandwich, fruit and veg, dairy produce and ready meals are located along one side with freezer cabinets at the rear and chilled wines and beers etc along the other side. Central display islands held a varied selection of non-chilled tinned and packaged produce. The Conveni-pack installation was carried out by WR, Leicester and commissioned in June by Daikin Airconditioning UK.
As well as achieving savings in electrical costs, the project, carried out by Daikin in association with the Co-operative Group, has solved a number of issues, mainly concerning in store temperatures. Foremost among these was the not uncommon convenience store problem of “cold aisles”. An unpleasant temperature gradient of around 40C at knee level and 120C at head level (at an ambient temperature of 270C) gave rise to a number of customer and staff complaints. Efforts to alleviate the problem by positioning infra-red heaters above the chilled case aisles areas were largely unsatisfactory and in any case only led to further electrical consumption.
As the store is in a residential area, the Co-op was also keen to reduce the noise generated by the fairly large and unsightly external plant. Also, the space occupied by the plant itself often hampered deliveries.
Commenting on the new Conveni-pack installation Bill Watson, technical consultant – refrigeration, Co-operative Group, states: “The system was chosen because of several constraints both within and outside the store. These included the cold store effect, which certainly appears to have been solved and energy consumption, which is down and all additional heating has now been removed.
Also, the new equipment has created more space in the delivery areas and its low footprint has enabled us to overcome all planning issues as well as noise sensitivities. Although it is still early days the system has clearly solved the problems that were initially identified and appears to be a resounding
The new outdoor units are smaller- and quieter
Daikin’s solution was based around the use of three Conveni-pack systems sized to deliver 40kW of refrigeration at -100C. Two ceiling recessed FXM fan coil units blow heat recovered air into canvas ducting, mounted at about 2.25m above floor level in areas adjacent to the freezer cabinets, chilled aisles and central store dry produce displays. Gentle and even warm air displacement ventilation is delivered to these areas at an angle of 60 degrees via jet nozzles fixed in the ducting.
One FXF 4-way blow ceiling cassette fan coil unit supplies conditioned air to the till and chilled wind and beer area, a further FXM ceiling concealed unit acting as an overhead entrance door heater. This new system maintains a pleasant temperature throughout the store of 200C ± 10C. Two 3-pipe outdoor condensers look after the store’s refrigeration, air conditioning and heating requirements – the third 2-pipe system supplies the chilled display cabinets.
Based around the use of Daikin DC inverter-driven variable refrigerant control, Conveni-pack provides constant liquid pressure and even refrigerant distribution throughout a single refrigerant circuit common to all functions. Variable refrigerant control, however, provides a number of other benefits, particularly during winter. Since it utilises exhaust heat from freezers and refrigerators, a100% heat recovery facility is available for heating the premises. Highly efficient operation results from an integral non de-frost feature, combining heat recovery heating and “free” heat extracted from the outside air.
Massive increases in electricity charges, rising overhead costs and increasingly stringent legislation against noise in residential areas now confront operators of convenience stores, small supermarkets and petrol stations etc. Conveni-pack represents a timely and much needed solution to these problems.
Conveni-pack offers users reduced energy costs plus the benefits and economies of combined freezing, refrigeration and efficient heat pump air conditioning and qualifies its owners for government’s Enhanced Capital Allowance (ECA) tax rebate.