Decarbonizing Grocery Stores

The global food system is currently responsible for a startling one-third of all greenhouse gas (GHG) emissions. Within this, grocery stores have control over approximately 7% of these emissions (referred to as scope 1 and 2 emissions). It is here that an exciting opportunity lies. By reducing these emissions, grocery stores can achieve substantial energy cost savings and position themselves as leaders in environmental change, boosting their standing among conscientious consumers and employees.

Scope 1 and Scope 2 Emissions Defined

Scope 1 emissions pertain to those directly linked to a grocer's operations, such as emissions produced by the store's refrigeration systems. On the other hand, Scope 2 emissions originate from the energy that grocers purchase and use, like electricity. Both scopes represent key areas where grocers can effect change.

The Roadmap to Lower Emissions

The first step in a grocery store's decarbonization journey is to reduce energy consumption. Considering that grocery stores spend an average of $3.95 per square foot annually on electricity and 24 cents on natural gas, a 10% reduction in energy costs can correspond to a similar uptick in profits. By upgrading lighting, optimizing refrigeration, and modernizing heating, ventilation, and air conditioning (HVAC) systems, grocery stores can lower their energy usage by an impressive 50%.

Illuminating Savings: Upgraded Lighting

Lighting upgrades are an easy yet effective way to trim energy consumption. By switching to LEDs with luminaire-level lighting controls, grocery stores can achieve notable energy savings. The use of daylight and occupancy sensor networked lighting controls integrated with Building Automation Systems (BAS) and the installation of energy-efficient LED parking lot lighting further enhance these savings. In fact, just by relamping with modern T8 lamps and electronic ballasts, stores can reduce their lighting energy consumption by 35%.

Efficiency Upgrades: HVAC Systems

Retrofitting HVAC systems with high-efficiency alternatives is another key to unlocking energy savings. By replacing outdated equipment with rightsized, high-efficiency alternatives, such as air-, water- or ground-source heat pumps and variable refrigerant flow (VRF) systems, grocery stores can significantly lower their energy use. Additional strategies like natural ventilation, energy recovery ventilators, and active thermal energy storage can further amplify these savings.

Addressing Humidity: Desiccant Dehumidification

Grocery stores in humid climates often rely on over-cooling and reheating to manage humidity levels. However, desiccant dehumidification presents a more energy-efficient alternative. By using solid or liquid chemicals to remove moisture from the air, this system conserves more energy and could even allow for the installation of smaller, more cost-effective air conditioning (AC) equipment.

Chilling Out: Refrigeration

By adopting low global warming potential (GWP) refrigerants, grocery stores can make their refrigeration systems more environmentally friendly. Other strategies include adding heat recovery systems to preheat hot water or ventilation air, replacing air-cooled condensers with evaporative condensers, and swapping out flash tanks with ejector systems for CO2 refrigeration units. Even adjusting defrost schedules can make a substantial difference, with demand-based defrosting proving more energy-efficient than fixed schedules.

Heating Things Up: Water Heating Solutions

Optimizing water heating systems can also result in significant energy savings. For small, distributed loads, point-of-use electric water heaters are an excellent choice. In larger applications, high-efficiency, connected heat pump water heaters or air-to-water heat pumps can yield more considerable energy savings.

Energy Savings from Wall to Wall: Building Envelope

The building envelope — comprising the roof, walls, windows, and doors of a grocery store — is another area ripe for energy-saving interventions. Recoloring the roof with a highly reflective shade, such as white, can minimize heat absorption, while additional insulation on exterior walls can enhance thermal performance. More advanced options include installing dynamic windows, thin triple windows, and vacuum glazing.

Harnessing the Sun: Renewable Energy

As the world rallies to increase the availability of renewable energy, grocery stores can contribute to this global effort by integrating on-site Solar Photovoltaics (PV). These systems, which can be installed on rooftops or serve as stand-alone structures in parking lots, can drastically reduce a store's carbon footprint and lead to substantial energy cost savings.

In Conclusion

In adopting these energy-efficient solutions, grocery stores play a crucial role in reducing our environmental impact and demonstrating their commitment to a sustainable future.