Efficiency Can be Just Another Controllable Cost

Energy efficiency can be achieved in ways other than with new technology. It can also prove to be a controllable cost, just as with labor and equipment. By developing an energy management system that establishes clear, measurable goals for energy performance, end users of industrial refrigeration facilities can realize a significant reduction in energy consumption, delivering cost savings that fall straight to the bottom line.

“There is an opportunity to save energy at these facilities beyond capital investment,” says Josh Bachman, a senior engineer at Cascade Energy. “Warehouses and food processors can save anywhere from five to 15 percent energy by doing a better job with what they have. It’s really about training their people to focus on energy efficiency.”

The key to a successful energy management system is executive support and employee engagement, Bachman says.

“Warehouses and food processors can save anywhere from five to 15 percent energy by doing a better job with what they have. It’s really about training their people to focus on energy efficiency.”

–Josh Bachman, a senior engineer at Cascade Energy

“The people who operate the equipment and make decisions every day on how to run the equipment have a huge impact on energy. They are your greatest asset for saving energy,” he says. “It’s important to address energy from an employee perspective rather than just with projects and installing technology. Training is one element of that but installing a management system surrounding energy is the biggest factor.”

An energy management system begins with setting policy, goals and responsibilities. The system should communicate long-range energy performance objectives and assign responsibility for reaching those goals to an individual energy “champion” or an energy team.

The next step is the planning and implementation. Current energy management practices can be assessed by using a performance scorecard. An energy map then displays a breakdown of energy usage and costs across the company. Planning also includes listing the actions to be undertaken over one or more years, such as improvements to operations and maintenance practices. It is critical to engage employees in this process and to empower individuals to look for areas where energy consumption can be reduced. Managers of this process need to periodically review energy performance by comparing actual to expected energy consumption.

Finally, there should be a system in place to regularly collect, store and analyze data so that performance relative to baseline is tracked on an ongoing basis.

Through this process, it is important that the leadership team supports and engages employees, and that energy goals are clearly defined. “Saying you’re going to cut energy by 20 percent in 10 years with no plan or budget to do so is a common stumbling block to success,” Bachman says.

Here are five ways an energy management program can train employees to reduce energy consumption:

Reduce system lift by raising suction pressure and lowering condensing pressure. “How far you can increase suction pressure is generally limited by space and product temperature requirements,” Bachman says. “Condensing pressure is limited by outdoor ambient weather conditions, coupled with the minimum pressure requirements unique to each facility’s refrigeration system. So, no one size fits all.”

Ensure that operations and maintenance include tuning setpoints and control strategies, calibrating sensors, cleaning evaporator coils, condenser coils and condenser spray nozzles, and staying on top of repairs.

Improve part-load performance of the big energy users on refrigeration systems: compressor, condensers, and evaporators. This equipment is designed for peak load conditions. The drawback is that peak load conditions occur rarely; most of the year the system is oversized for the job. Utilizing speed control with variable frequency drives (VFDs), by cycling evaporator fans in the absence of speed control, and by controlling evaporators, condensers and compressors as a group helps to maximize part-load efficiency. “Ideally, if you only need 50 percent of the full capacity of a compressor, it would only require 50 percent of full power,” Bachman says.

Optimize defrosts by defrosting only when necessary and for only as long as necessary. With hot-gas defrosts, minimize false loading from uncondensed hot gas flowing to the suction side. “Defrosting an evaporator is an energy-intensive activity,” Bachman says. “You’re adding heat to a cold space, and whatever heat doesn’t go towards melting the frost runs down the drain and winds up in a space that must be removed by the refrigeration system. Because evaporators are out of sight and out of mind and icing up a coil is a huge headache, the tendency is to be safe and over-defrost.

Reduce refrigeration loads. There are several ways to accomplish this, including maintaining good door practices, cycling evaporator fans, and minimizing lighting use in refrigerated spaces.

“In the end, this is about recognizing that energy efficiency is about people and not technology,” Bachman says.