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Doored cabinet testing reveals huge energy saving potential for retailer

Previous tender regime would have resulted in ‘wrong buying decision’ says retailer

Central England Co-operative has proclaimed the success of its new benchmarking process for refrigerated display cases, saying that the bespoke testing programme has resulted in a specification that it simply wouldn’t have made under its previous tendering regime.

Central England Co-operative Facilities & Administration Manager Kevin Collins said that given the major capital investment that display case specification demands – in addition to the carbon footprint and ongoing operating costs – the existing tender process needed to be revised.

The retailer has over 400 trading outlets across 16 counties, with a turnover of £927m last year.

Mr Collins said: “We decided that procurement of refrigerated display cases warranted a more vigorous process than was previously being conducted.”

A test programme was devised in collaboration with independent consultant Mistral Technical Services to benchmark a 2500mm medium temperature display case fitted with wardrobe-style doors to the retailer’s specification from four shortlisted case providers.

The supplier shortlist was drawn up according to traditional metrics, the retailer said: capital cost; ability to deliver to the store development programme; and energy figures, based upon the manufacturer’s published data, in line with the testing methods in ISO23953:2014 Climate Class 3 (25ceg C/60% RH).

Mr Collins said he was keen to understand the energy performance in a real store environment, so a comparison of how four cases compared under the same conditions against a consistent baseline was undertaken in a portioned off non-trading section of a store for a one-month test period during last summer. The four cases were each piped to independent condensing units from the same manufacture and model. Performance was logged using an energy monitoring system with factory-fitted case probes, supplemented with a product probe installed in the identical position in each case.

The retailer then monitored factors such as energy monitoring; air-flow; insulation; and structural integrity. Retail colleagues were invited to assess any merchandising issues and to score the cases.

The testing results arrived at one clear winner, Mr Collins said, with the best-performing case a huge 43 per cent more energy efficient than the worst. He said: “The winning case was the sole model that was designed specifically for operation with doors, with a corresponding evaporator coil design - all the other cases were designed for open application and then fitted with doors.” The coil design also led to a 25 per cent reduction in refrigerant charge compared to the other cases – a factor that will prove particularly beneficial in reducing the retailer’s direct carbon emissions, he noted.

The retailer’s smoke testing revealed that the adapted designs suffered from excessive air spillage upon door openings – and some with the doors closed. This was confirmed in thermal imaging of the cases, which also showed the superior insulation properties of the best performing case - the only one designed for dual carcass.

The testing also blew apart the widely accepted belief that with open cases, the larger the total display area, the larger the penalty in energy performance. The trials showed that best performing case on energy consumption also had the largest total display area ‘by a significant distance’ the retailer said, thanks to its reduced evaporator coil design and the fact it had been designed for doored use from ‘the ground up’.

According Mr Collins, the new benchmarking process has revealed a host of significant new findings:

  • The traditional tendering approach would have arrived at the wrong buying decision, with the historical approach prioritising initial capital expenditure
  • Any retailer standardising on a selection of medium temperature cases with doors should investigate to ensure they are buying equipment designed specifically for doored applications
  • The best energy performer needs to be judged against air flow efficiency, evaporator design, component selection and thermal integrity
  • Whilst ISO23953:2014 Climate Class 3 data is an invaluable benchmark tool and not in dispute, it is also important to test against typical store conditions (such as ISO23953:2014 Climate Class 0 (20 deg C/50%RH) to optimise on capital spend and energy usage.

Mr Collins said he is happy to elaborate further his experience of the testing programme and its findings, in a bid to help the retail sector reduce its carbon footprint.

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