Reducing energy consumption and greenhouse gas emissions from the European retail sector

Copyright © 2018 Institute of Refrigeration REFRIGERATION AIR CONDITIONING HEAT PUMPS The knowledge hub for refrigeration, air conditioning and heat pumps Copyright © 2025 Institute of Refrigeration Elias Eid, Alan Foster MInstR, Graciela Alvarez and Judith Evans FInstR Reducing energy consumption and greenhouse gas emissions from the European retail sector Winner of the 2022/2023 Ted Perry Award 2 Presented before the IOR on 15 May 2025 REFRIGERATION AIR CONDITIONING HEAT PUMPS Reducing energy consumption and greenhouse gas emissions from the European retail sector Why you should attend: 1. To gain insights into how electrical carbon grid trends and strategic actions can help European supermarkets reach net-zero targets by 2050. 2. To understand how early adoption of innovative technologies leads to faster carbon reductions and greater long-term impact. 3. To learn how climate change will affect supermarkets across different European locations by 2050. Abstract The retail sector significantly contributes to global greenhouse gas (GHG) emissions, with refrigeration being a major energy consumer. This study investigates decarbonisation strategies for European supermarkets using an EnergyPlus modelling across six locations in France, Italy, Lithuania, Norway, Poland, and the UK. By incorporating projected climate data and electrical grid carbon intensities (EGCIs) from 2020 to 2050, the study evaluated impact on GHG emissions. Results show that electricity grid decarbonisation across all locations had the biggest effect on reducing emissions. Combining strategies, such as increasing store deadband temperature, installing doors on chilled cabinets, using air-source heat pumps (ASHPs), implementing 20% lower energy consumption cabinets and integrating solar panels, achieved carbon savings between 68.0% to 93.8%. Among individual strategies, solar panels proved most effective, particularly in high solar exposure regions. Climate change had a small impact on overall energy use. These findings offer insights for policymakers and retailers to support net-zero in the European retail sector. Keywords: Retail, Greenhouse gas emissions, Refrigeration, Carbon neutrality, EnergyPlus, Sustainable practices Presented before the IOR on 15 May 2025 3 REFRIGERATION AIR CONDITIONING HEAT PUMPS Reducing energy consumption and greenhouse gas emissions from the European retail sector 1. Introduction The retail sector is a major contributor to global energy consumption and greenhouse gas (GHG) emissions, raising significant environmental concerns. Retail operations account for more than 25% of global GHG emissions [1]. Additionally, studies indicate that food and agriculture contribute to 26–35% of global emissions, with approximately 18–29% arising from the food supply chain [2,3]. Refrigeration plays a significant role in this footprint. Reports indicate that about 60% of food is refrigerated at some stage in the supply chain, and perishable foods are responsible for approximately 70% of GHG emissions within the food system [4]. Global warming further aggravates these challenges, with rising temperatures increasing the demand for cooling and refrigeration. The World Meteorological Organisation (WMO) has confirmed that 2024 was the warmest year on record, based on six international datasets. The past ten years (2015-2024) have all ranked among the ten warmest on record, highlighting an extraordinary streak of record-breaking temperatures. According to the WMO’s consolidated assessment, the global average surface temperature in 2024 was 1.55 °C above the 1850–1900 baseline, with a margin of uncertainty of ± 0.13 °C. This likely marks the first full calendar year in which the global mean temperature exceeded 1.5 °C above pre-industrial levels [5]. Given these trends, there is an urgent need to develop and implement better solutions in the retail sector. As part of the European Green Deal, the ENOUGH project (European food chain supply to reduce GHG emissions by 2050) was established to align with the EU's Farm-to-Fork strategy. This initiative aims to transform the European food sector into a more sustainable, resilient, and low-carbon system. A key focus of the project is reducing emissions in supermarkets, one of the most energy-intensive types of commercial buildings. The complexity of supermarkets arises from the interaction between external climate conditions, refrigeration systems, heating, ventilation and air-conditioning (HVAC) systems, lighting, and internal heat loads from equipment. These subsystems interact dynamically, with heat loads varying throughout the year. Therefore, understanding these interactions is crucial for optimising energy use and reducing emissions. Several researchers have explored supermarket energy modelling and emissions reduction strategies [6,7,8,9,10,11,12,13]. For example, the authors of this paper developed an EnergyPlus simulation for a supermarket in Paris, evaluating interventions such as installing doors on refrigerated cabinets and using R-744 refrigerant while incorporating climate change projections to 2050 [14]. However, our focus was limited to specific interventions within a single climate zone. This research aims to expand on this work and evaluates the energy and carbon emission impacts of a medium-sized supermarket across six European countries: France, Italy, Lithuania, Norway, Poland and the UK. By incorporating projected electrical grid carbon intensity (EGCI) and climate data up to 2050, the study assesses the effectiveness of integrating different energy and carbon saving strategies. The selected locations represent diverse climatic conditions, various heating fuel sources and different EGCIs, making them ideal for evaluating different decarbonisation pathways. The findings from this study demonstrate the decarbonisation potential for supermarkets through to 2050, offering critical insights for policymakers, retailers, and industry stakeholders and contributing to the broader goal of achieving carbon neutrality in the European retail sector. 2. Materials and methods The methodology used to develop the study was composed of three stages: identifying and reviewing strategies, modelling of supermarkets, and highlighting the decarbonisation potential of the retail sector. 4 Presented before the IOR on 15 May 2025 REFRIGERATION AIR CONDITIONING HEAT PUMPS Reducing energy consumption and greenhouse gas emissions from the European retail sector 2.1. Identification of strategies As part of the ENOUGH project, 95 different technologies and strategies that retail stores could apply to reduce carbon emissions and energy consumption were reviewed and ranked [15]. Scope 1 and 2 emissions were covered which encompass emissions from direct fuel use (electricity/gas) and emissions from leakage of refrigerants. Scope 3 emissions were not included as these will originate from outside the retailers’ boundaries. The reviews were used to identify the individual strategies that had the most potential in food retail stores. Only strategies with a high technology readiness level (TRL 8 or 9) were considered as carbon emissions options that were not on the market were very difficult to quantify and often had varied claimed savings. Technologies with high TRL, high potential savings, and that were able to be modelled with EnergyPlus were then selected for this study. This included installing doors on open-fronted cabinets, adjusting the ambient store temperature dead band by 2 K, implementing air-source heat pumps (ASHP), improving refrigerated cabinets by 20%, and installing solar panels on supermarket rooftops. 2.2. Mathematical modelling Mathematical modelling was then used to assess impacts from 2020 through to 2050 considering changes due to global warming and changes in the EGCI as well as the impact of combined strategies. EnergyPlus 2022 v22.2.0 simulation engine was used to calculate the total energy consumption for the modelled scenarios. SketchUp Pro 2022 (Trimble Inc.) was used to draw and create the model geometry. OpenStudio 2023 v1.5.0 (by NREL, ANL, LBNL, ORNL, and PNNL) was used as a graphical user interface to add and modify properties such as weather files, construction, materials, internal loads, schedules, water, HVAC, and refrigeration systems. The environmental impact was characterised by the total equivalent warming impact (TEWI). The validated baseline supermarket model from Eid et al. [14] developed using EnergyPlus and located in Paris was then used for the other EU locations. The geometry for the 2,100 m2 supermarket had 5 zones: sales, offices, dry storage, cold storage, and a machine room, with areas of 1,085 m2, 111 m2, 267 m2, 526 m2 and 111 m2, respectively. The height of all zones was 6 m. Table 1 only shows a subset of the model inputs for the supermarket, and further inputs for the baseline model, along with all necessary information, can be found in Eid et al. [14]. The documentation of the U.S. Department of Energy highlights all the equations used to calculate the loads across all modelled scenarios in EnergyPlus [16]. Presented before the IOR on 15 May 2025 5 REFRIGERATION AIR CONDITIONING HEAT PUMPS Reducing energy consumption and greenhouse gas emissions from the European retail sector Table 1. A subset of the model inputs Variables Inputs Source HVAC system Cooling DX Rated COP 3EnergyPlus default Heating efficiency 1 (electric), 0.8 (gas) Assumption Fan total efficiency 0.7 EnergyPlus default Heating thermostat 21°C Day - 19°C Night Real store data Cooling thermostat 24°C Real store data Refrigeration system (R-744 booster) Compressors Bitzer-2GSL-3K-4SU (Low stage) Bitzer4FTC-20K (High stage) Assumption Evaporating T Chilled/Frozen: -5/-30°C [17] Defrost 1h/day (total) Chilled: Off cycle Frozen: 1400 W/m Real store data Anti-sweat heater None for chilled cabinets 100 W/m for frozen cabinets Real store data Minimum condensing T 10°C [18] Transition T 27°C [18] Design T gas cooler 3 K greater than ambient T (transcritical) 10 K greater than ambient T (subcritical) [18] Receiver pressure 40 barg [18] Display cabinets (all remote) Case length Chilled/Frozen: 83.75 m/18.7 m Real store data Case height 1.5m Real store data Operating T Chilled/Frozen: 3°C /-18°C EnergyPlus default Rated cooling capacity Chilled: 1000 W/m (without doors) and 500 W/m (with doors) Frozen: 400 W/m Assumption Fan power 30 W/m Assumption Light power 20 W/m Assumption Cold chambers Number 2 Chillers and 6 Freezers Real store data Total area Chillers/Freezers: 43 m2/43 m2Real store data Operating T Chillers/Freezers: 3°C/-18°C Real store data Door height 2 m Real store data Cooling coil capacity 4690 W EnergyPlus default Fan 735 W EnergyPlus default Light 120 W EnergyPlus default Defrost 2500 W EnergyPlus default 6 Presented before the IOR on 15 May 2025 REFRIGERATION AIR CONDITIONING HEAT PUMPS Reducing energy consumption and greenhouse gas emissions from the European retail sector 2.3. Locations and assumptions for baseline simulations It was assumed that the baseline simulations across the 6 locations: France, Italy, Lithuania, Norway, Poland and the UK, were set for the year 2020. All simulations used an R-744 booster system and only differed in terms of heating fuel source (natural gas (NG), electric resistance, or ASHP) and weather files (specific to each city). All other elements remained the same in the simulations. Similar to the work of Eid et al. [14] for France and the UK, EnergyPlus weather files for the other locations were obtained from https://energyplus.net/weather. The selected cities for this study along with the fuel sources used for heating, the exact location of the weather files applied, and the average ambient temperature in each location are listed in Table 2. Table 2. Differences in the baseline conditions across the 6 locations Heating fuel source Weather file (city) Ambient temperature (average) France Electric resistance Paris (Orly) 11.1°C Italy NG Rome 15.8°C Lithuania ASHP Kaunas 6.8°C Norway ASHP Oslo (Fornebu) 6.6°C Poland NG Warsaw 8.3°C UK NG London (Gatwick) 10.2°C 2.4. Climate change The EnergyPlus weather files for the 6 locations were shifted to the period 2041-2060 period (termed 2050), considering historical climate change (https://weathershift.com/). The methodology for this process is detailed in Dickinson and Brannon [19]. The 2050 weather files employed representative concentration pathways (RCP) 4.5. According to the Intergovernmental Panel on Climate Change (IPCC), RCP 4.5 highlights moderate emissions peaking around 2040 and then decreasing. The objective was to examine how climate change affects the energy demand of the baseline supermarkets in the different locations. Figure 1 illustrates the monthly average ambient temperatures for 2050 under RCP 4.5 scenario across the 6 locations. Figure 1. Monthly average ambient temperatures for 2050 under RCP 4.5 scenario across the 6 locations Presented before the IOR on 15 May 2025 7 REFRIGERATION AIR CONDITIONING HEAT PUMPS Reducing energy consumption and greenhouse gas emissions from the European retail sector 2.5. Electrical grid decarbonisation The study analysed the impact of the future EGCI between 2020 and 2050 for the 6 locations (where applicable). This was done to determine and demonstrate the decarbonisation potential of the baseline scenario (with no interventions) and the combined model where all the carbon-saving strategies were implemented together. Figure 2 presents (where available) the changes to the EGCI in the 6 locations. Information on future EGCI was only available for 4 of the countries modelled (France, Lithuania, Poland (to 2040 only) and the UK). Therefore, for Poland, extrapolation was performed using three points (2030, 2035, and 2040), as Poland experienced rapid decarbonisation between 2020 and 2030, followed by a slower decarbonisation trend from 2030 to 2040. A quadratic polynomial curve (degree 2) was fitted to these points, and the extrapolated section is represented as a dashed line on the Poland curve. No information on future EGCIs was available for Italy and Norway. However, Norway already has the lowest EGCI among the six countries considered. Additionally, Italy has seen a decline in EGCI over the past 20 years, and if this trend continues, Italian supermarkets will likely become much lower carbon emitters by 2050 [20]. The EGCI for France was taken from Statista [21], for Lithuania from Lithuanian experts that calculated these based on official figures, for Poland from Statista [22], and for the UK from the UK BEIS [23]. The 2020 EGCIs for Italy and Norway were taken from EEA [24] and Equinor [25], respectively. Figure 2. EGCI for the 6 locations studied 2.6 TEWI The TEWI characterises CO2e emissions and is a useful tool to study the impact of systems on global warming. The TEWI combines the direct and indirect emissions of CO2e. TEWI is based on the following relation: TEWI=(GWP×m×L)+(E_gas×β_gas)+(E_electric×EGCI) Eq. (1) Where TEWI is the mass of CO2e produced during a year (kg); GWP is the global warming potential of the refrigerant (GWP�-744 = 1); m is the refrigerant charge of the store (kg), which was 380 kg [15]; L is the refrigerant leakage percentage per year (%/year), which was 10%; Egas is the NG energy consumption per year of the store 8 Presented before the IOR on 15 May 2025 REFRIGERATION AIR CONDITIONING HEAT PUMPS Reducing energy consumption and greenhouse gas emissions from the European retail sector (kWh/year); βgas is the CO2e emission factor for the combustion of NG (kgCO2e/kWh) which was 0.18 kgCO2e/ kWh [26]. Eelectric is the electrical energy consumption per year of the store (kWh/year); EGCI is the CO2e emissions per kWh of electrical energy produced (kgCO2e/kWh). (GWP x m x L) and (Egas x βgas) represent direct CO2e emissions from refrigerant leakage and NG combustion, respectively; (Eelectric x EGCI) are indirect emissions of CO2e associated with electrical energy consumption. 2.7. Modelling strategies Based on the technological reviews, the selected strategies applied for the 6 locations in this study were: 1. Strategy 1: Increase the dead band temperature of the HVAC by 2 K, by increasing cooling and decreasing heating set points by 1 K. 2. Strategy 2: Doors were added to the open fronted chilled cabinets. 3. Strategy 3: Change heating from gas or electric resistance to ASHP (for relevant scenarios) with a nominal coefficient of performance (COP) of 2.75. 4. Strategy 4: Refrigerated cabinets with 20% lower energy consumption (compressor, evaporator and condenser fans, defrost and anti-sweat heater, and case lighting) were applied for chillers and freezers. 5. Strategy 5: Solar photovoltaic (PV) panels were installed on the supermarket’s roof. The electricity generated was calculated using the RETScreen v9.0 software tool. RETScreen uses published local data for daily solar radiation on a horizontal surface in kWh/m2/day for each month. The monthly output was calculated based on the fixed orientation of the PV panels, which were positioned at a 15° angle to the horizontal, their 6 different locations, and an assumed efficiency of 15%. The available energy from the solar panels was removed from the annual energy consumed by the store. It was therefore assumed that all solar energy generated could be used by the store (immediately or through energy storage). 6. Combined model: All the strategies above were combined in a single model to understand their potential impact on overall energy use and carbon emissions. 3. Results and discussion 3.1. Impact of climate change on the baseline supermarkets This section shows the impact of climate change and the EGCI on the supermarket in the 6 locations. Figure 3 show the impact of climatic temperature change on energy consumption for the 6 locations in 2020 and 2050. The graph presents information divided into heating, cooling (HVAC), lighting, interior equipment, fans, pumps, water systems and refrigeration. It is worth noting that space cooling was negligible because the supermarket had open-fronted chilled cabinets. As a result, the cold air from the cabinets naturally cooled the aisles, significantly reducing the need for cooling. Modelling showed that climate change had both positive and negative effects on energy use, depending on the location. It increased energy consumption in France, Poland and the UK but decreased it in Italy, Lithuania and Norway. However, despite these variations, the overall differences in energy consumption between 2020 and 2050 were small (less than 2%). The low impact of increasing climatic temperature was due to a balance between the heating and cooling demands on the supermarkets. As climatic temperatures increased, there was less energy demand for heating, but this was balanced by the increased energy demand for cooling and refrigeration. Presented before the IOR on 15 May 2025 9 REFRIGERATION AIR CONDITIONING HEAT PUMPS Reducing energy consumption and greenhouse gas emissions from the European retail sector Figure 3. Impact of climatic temperature change on annual energy consumption of the supermarket between 2020 and 2050 in the 6 locations. 3.2. Impact of future EGCI changes on the baseline supermarkets Figure 4 presents the total annual carbon emissions for the stores in each country. Over time, the EGCI is predicted to decrease considerably (as seen in Figure 2) and this had a major impact on the emissions from the stores. The store in Poland had the highest carbon emissions based on data up to 2050, reaching 126.1 tCO2e/ year, though the trend suggests a continued decline beyond this period. In London, despite the EGCI dropping to nearly zero (0.003 kgCO2e/kWh) by 2050, the carbon emissions remained at 41.5 tCO2e/year as the store was still heated by NG. In Paris, where electric resistance heating was used, emissions reached 17 tCO2e/year by 2050 due to the EGCI of 0.023 kgCO2e/kWh. In Lithuania, where heating was supplied by an ASHP, total emissions fell to nearly zero (2.7 tCO2e/year) by 2050 due to the nearly zero EGCI (0.004 kgCO2e/kWh). Although future EGCIs for both Norway and Italy were unavailable, emissions in Norway were already low in 2020 at 5.3 tCO2e/year and are expected to be near zero by 2050, as an increase in the 2020 EGCI is unlikely, while Italy recorded 152.1 tCO2e/year in 2020. Figure 4. Impact of future EGCI changes on total carbon emitted by the supermarket in the 6 locations. 16 Presented before the IOR on 15 May 2025 REFRIGERATION AIR CONDITIONING HEAT PUMPS Reducing energy consumption and greenhouse gas emissions from the European retail sector 16. U.S. Department of Energy, 2024. EnergyPlus Version 24.1.0 Documentation. Engineering reference. Available online: https://energyplus.net/assets/nrel_custom/pdfs/pdfs_v24.1.0/EngineeringReference.pdf 17. Emerson, 2021. CO2 Product Guide 2021 for Refrigeration Applications. Available online: https://www.copeland.com/ documents/co2-product-guide-2021-for-refrigeration-applications-en-gb-4217772.pdf 18. Sharma, V., Fricke, B., Bansal, P., 2014. Comparative analysis of various CO2 configurations in supermarket refrigeration systems. International journal of Refrigeration, 46, 86-99. 19. Dickinson, R. and Brannon, B., 2016. Generating future weather files for resilience. In Proceedings of the international conference on passive and low energy architecture, Los Angeles, CA, USA (pp. 11-13). 20. Statista, 2024. Carbon intensity of the power sector in Italy from 2000 to 2023. Available online: https://www.statista. com/statistics/1290244/carbon-intensity-power-sector-italy/ 21. Statista, 2020a. Carbon intensity outlook of the power sector in France from 2020 to 2050. Sourced by Aurora Energy Research. Available online: https://www.statista.com/statistics/1190067/carbon-intensity-outlook-of-france/ 22. Statista, 2020b. Carbon intensity outlook of the power sector in Poland from 2020 to 2040. Sourced by Aurora Energy Research. Available online: https://www.statista.com/statistics/1190077/carbon-intensity-outlook-of-poland/ 23. UK BEIS, 2023. Valuation of energy use and greenhouse gas (GHG) emissions, supplementary guidance to the HM Treasury Green Book on Appraisal and Evaluation in Central Government. 24. EEA, 2023. Greenhouse gas emission intensity of electricity generation in Europe. Available online : https://www.eea. europa.eu/en/analysis/indicators/greenhouse-gas-emission-intensity-of-1?activeAccordion= 25. Equinor, 2021. Greenhouse gas and methane intensities along Equinor's Norwegian gas value chain. Available online at: https://www.equinor.com/content/dam/statoil/documents/sustainability-reports/greenhouse-gas-and-methaneintensities-along-equinors-norwegian-gas-value-chain-2021.pdf 26. UK Government, 2024. Greenhouse gas reporting: conversion factors 2024. London, UK. Available online: Greenhouse gas reporting: conversion factors 2024 - GOV.UK