Energy-efficient HVAC systems are necessary for grocery stores to be competitive. Understanding and properly using case credits in the system design of refrigerated display cases is critical in meeting this goal. In addition, implementing different return air paths can have significant impact on system heating/cooling capacities and comfort for shoppers. This article explains case credits and how they affect HVAC system design. It also explains the impact different return methods (in conjunction with appropriately applied case credits) can have on heating and cooling capacities and related energy use.