In part two of this series, learn how to maximize the efficiency of facility systems and reduce energy consumption and costs.
Refrigerated warehouse are some of the most energy intensive industrial facilities on the planet. In fact, energy consumption represents the second highest operating expense in these facilities, trailing only labor costs. As cold storage companies seek to reduce the cost and environmental impact of their operations, they have two
options. They can pursue capital improvement projects, which offer substantial savings but require investments in engineering, design, bidding and project management. Or they can work to improve the energy efficiency of their existing systems—typically at little or no cost. These adjustments, repairs and fine-tuning may take some time and ongoing maintenance, but the resulting cost savings are invariably worth the effort.
Refrigerated warehouses typically have high intensity discharge (HID) lighting, such as metal halide or high-pressure sodium, fluorescent fixtures or lightemitted
diode (LED) fixtures. Ensure that light levels do not exceed corporate or customer design criteria. Also, install low-cost motion controls and set sensor time delays to the minimum allowable delay for facility use patterns, safety and manufacturer specifications. Cleaning fixture lenses will not save energy, but will ensure maximum performance from the system.
Cold storage facilities typically have roll-up doors for trucks, and automatic doors between the dock and coolers or freezers. When they are left open, close slowly or don’t close at all, cold air escapes and energy consumption increases. All door seals, controls and opening mechanisms should be inspected, tuned and repaired regularly. Freezer doors with defrost systems should be tuned to minimize heating requirements. High-performance recirculatory air doors should be tuned for proper air flow and heating of the air stream.
Many refrigerated warehouses have subfloor heating systems that prevent ice from forming under the concrete slab and heaving the floor. In some cases, the floor heating system puts excessive heat under the floor, which migrates to the freezer as refrigeration load. Adjust and monitor subfloor temperatures to minimize this load. Also, ensure that the heating system design (whether air, glycol or heat cable) does not require inefficient refrigeration system set points.
Battery chargers and hydrogen fuel cells Forklifts, pallet jacks and other heavy machinery used in refrigerated warehouses operate on batteries that need to be recharged. By adjusting the charging schedule and minimizing battery charges at peak times, cold storage operators can take advantage of lower energy rates and avoid chargers causing or contributing to facility peak demand.Hydrogen fuel cells can replace traditional batteries to improve productivity and eliminate charging hassles, but there may be tradeoffs in overall energy use and cost.
Offices within a refrigerated warehouse have lighting, HVAC and plug loads that can be optimized to improve energy efficiency. Motion sensors can be used for interior lights and photo cells can be used for parking lots and exterior lighting. HVAC controls can be optimized and setback strategies can be utilized to reduce energy use. Office equipment such as printers, workstations and monitors typically have standby modes and energy efficiency features that should be employed. Although offices do not use a significant portion of total energy, this is often the environment where employees can be highly engaged. Utility rates and demand response programs.
In some areas, utility rates vary by time of day or day of week. Minimizing energy usage at peak times can dramatically reduce refrigerated warehouse operating
costs. Electricity bills and utility rate schedules should be reviewed, understood and acted upon. Many local utilities offer different rate schedules, and will conduct analyses to determine which is best for a particular facility. Others offer demand response programs that pay facilities to shed loads when utility resources or infrastructure are stressed.
In deregulated service territories, cold storage companies have an opportunity to shop for the best provider and rate, balancing cost savings and market risk.