CHICAGO — The days of convenience-store operators selecting their next walk-in cooler or freezer by simply measuring the installation space, satisfying a price point and choosing a model that kept cold things cold and frozen things frozen are in the past. In 2016, the new U.S. Department of Energy energy-efficiency requirements for refrigerated storage units came into full effect. The regulations increased the thresholds regarding the energy consumption of the walk-in unit’s thermal “envelope” (doors, walls, floor and ceiling). While existing cold-storage units were grandfathered in, operators who want or need to purchase new equipment will have to buy those that satisfy the new regulations.
Therefore, c-store operators should take note of four considerations before selecting their next walk-in cooler or freezer.
Optimized energy efficiency requires that the walk-in unit’s R-value—the ability of the unit to resist energy flow into it—can meet the refrigeration system’s requirements. The lower the unit’s R-value, the greater the refrigeration capacity needed. Other variables include the type and temperature of the stored food, the volume of product that will move through the unit, the location of the refrigeration system and how frequently the walk-in unit will be accessed daily. The ability of the walk-in unit’s framing system to prevent the intrusion of heat will help keep the R-value at a level that optimizes the unit’s energy consumption and overall life-cycle performance.
The type of insulation in the doors, walls and ceiling determines the cooler or freezer’s R-value and is critical to the proper sizing and selection of the refrigeration system. There are generally two types of insulation used in walk-in units: foamed-in-place polyurethane and extruded polystyrene. Polyurethane is preferred because it has the highest R-value per inch thickness of any building insulation. Meanwhile, polystyrene can lose an average of 21% of its R-value over a 12-year period.
Things to consider include the required holding temperature (cooler or freezer); weight and temperature of product entering the cooler or freezer; the amount of air filtration through the opening and closing of the doors; and the climate and elevation of the c-store location.
The first requirement is that the walk-in unit fits the footprint of the application. The unit must also be able to accommodate all the ancillary equipment that will be required for its operation, including the piping runs for the refrigeration, electrical and plumbing components. It is critical to use a qualified installer who can do the installation properly and in a way that meets local code requirements, national certifications and energy-efficiency demands.
There is nothing more off-putting than a walk-in storage unit with doors streaked by condensation. This occurs most often in geographic areas with consistently high temperatures and humidities, and it indicates a walk-in that is not doing its job. Any of the condensation that drips and pools on the floor also creates a slip-and-fall risk.
Most of these condensation issues occur around the doors, because they are subjected to daily open/close cycles and general abuse. New types of door and wall frame/rail systems offer a replacement to traditional wood structural framing and deliver optimal thermal-envelope performance and lower energy costs; create an improved carbon footprint; and offer scalability for use with any size or configuration of walk-in storage unit. These framing systems increase R-values to a level that slows the rate of heat flow and condensation formation while limiting issues concerning life-cycle performance that can plague traditional wood-framed systems.
Walk-in coolers and freezers are integral components of a successful c-store operation from the standpoint of operation, efficiency and driving sales. Stricter energy-efficiency standards have made it imperative that c-store operators give due consideration to the four critical factors that will help determine if their cold-storage units will be in compliance.
James Costanza is a technical fellow for KPS Global Inc., Fort Worth, Texas. Reach him at email@example.com.