If performed properly, retrofits of open cases with glass doors will lead to sizable reductions in infiltration loads, reducing overall case heat loads by 50-80 percent as compared to the original open case performance, according to laboratory studies and experts interviewed during the development of this guide. Additional system improvements performed concurrently, such as upgrading fan motors, installing higher-efficiency lighting, and raising case saturated evaporator temperatures, can further reduce the heat load from the refrigerated display case.
In light of these substantial reductions in refrigeration load, it is imperative that the refrigeration system configuration be reevaluated to match system operation to the load profile. According to experts interviewed, improper reconfiguration of refrigeration systems is the predominant cause of case retrofit projects not delivering the expected results. The following sections outline guidance for properly reconfiguring refrigeration systems after retrofitting open cases with doors.