Refrigeration (cooled storage)
Food retailers rely on refrigeration to preserve and extend the shelf life of perishable goods. Cooled storage refers to a wide range of commercial refrigeration equipment, including open shelf displays, doored shelf displays and sub-ambient or frozen storage. Units are generally powered by electricity and employ refrigerants (also called working fluids) to exchange heat.
There are two key elements to consider with regards to emissions from cold storage and refrigeration:
1. The energy consumption and efficiency of the refrigeration equipment.
2. Fugitive emissions caused by refrigerant leaks.
Although refrigeration falls into second place for energy consumption across the retail sector, food retail stores that require refrigeration have on average up to 50% higher energy usage than other retail buildings per square metre of floor area. Refrigeration covers a range of different applications within retail, from in-store display and storage through to cold store warehouses. Each refrigeration end use has a number of variables that can affect the overall contribution to retail emissions, including:
- Efficiency of technology – age of the unit and inclusion of energy saving options impact overall energy use.
- Maintenance – infrequent cleaning and commissioning can lead to condensation build-up, mechanical faults, heat leakage and overall inefficiencies in temperature control.
- Refrigerator type – open shelved systems leak significantly more heat than doored systems.
- Stocking behaviours – overstocking displays and stocking products that have warmed in transit both reduce cooling efficiency.
Refrigerants are the working fluid in refrigeration equipment that absorb, transport and reject heat to achieve cooling. Unfortunately, cold storage systems regularly leak refrigerants from joints, valves, fittings and pipes. Infrequent maintenance, large changes in temperature and vibration from machinery can all cause small leaks. Given the high global warming potential of many refrigerants, these small leaks can build up into a significant source of emissions.
Leaks of hydrofluorocarbons (HFCs) (or ‘F-gases’) are a major component of refrigeration emissions. These leaks are estimated to contribute around 25% of the total emissions from cold storage, although the proportion varies considerably by store. Industry data suggests that some retailers suffer far higher levels of leakage and associated emissions.
HFCs are currently used as replacements of hydrochlorofluorocarbons (HCFCs) and chlorofluorocarbons (CFCs), because HFCs do not deplete the ozone layer. However, given the high global warming potential of HFCs, the Kigali Amendment to the Montreal Protocol aims for the phase-down of HFCs by cutting their production and consumption. Ratified by 65 countries, the amendment entered into force on 1 January 2019, with the goal to achieve over 80% reduction in HFC consumption by 2047.
F-gas emissions accounted for 3% of UK greenhouse gas emissions in 2017. Abatement technologies at halocarbon production plants have cut F-gas leakage by over 99%, so the largest source of emissions is now the refrigeration, air conditioning and heat pump (RACHP) sector, where emissions are released due to refrigerant leakage from appliances.
Emissions are reported as scope 2 for the energy consumption associated with the refrigeration and scope 1 for the fugitive emissions associated with the release of refrigeration gasses.
Routes to decarbonisation for refrigeration
Energy consumption from refrigeration can be reduced through efficiency measures. Installing efficient support technologies can yield major per unit energy savings. For example, adding transparent doors to open display systems typically results in 20-50% energy savings, and simple changes like LED canopy lights typically result in 5-10% energy savings. Regular maintenance is another crucial, and inexpensive, way to ensure energy performance. Cleaning and commissioning allow for better temperature management and more precise control over power draw. Good habits, like properly stocking displays, turning off lights during off hours and covering units during off hours also reduce energy demands.
Over time, as the electricity grid decarbonises the emissions from refrigeration will reduce accordingly.
For fugitive emissions, one key action is to transition away from refrigeration gasses with high global warming potential to systems that utilise low (<150) or zero global warming potential refrigerants. Food retailers should use the regulatory HFC phase-down as an opportunity to review their refrigeration strategically. Instead of opting for the next available refrigerant that meets the regulation, opportunities for utilising natural and zero global warming refrigerants should be explored.
 Net Zero Technical Report (May 2019) – Committee on Climate Change
 Refrigeration: A guide to energy and carbon saving opportunities (2019). The Carbon Trust.