In some distribution center applications, but more often in manufacturing projects, Stellar also incorporates CO2-based refrigeration to boost system capabilities while lowering energy costs.
"We can turn an ammonia refrigeration system into a CO2-ammonia cascade system through certain modifications, boosting throughput by a spiral freezer, for example, allowing it to bring temperatures lower more quickly." In these situations, Lowery explains, CO2 functions more efficiently than ammonia for lowering temperatures quickly, but because it brings temperatures so low, it's not typically applicable to cold storage.
"However there are a number of third-party warehouses that do batch-freezing of product, for example, a cold storage facility that brings in product from a local fresh chicken supplier and needs to bring the temperature down within 20 hours. We can take an existing plant and apply this kind of technology to make it considerably more efficient," he says.
Automated energy management systems are another technology that can help distribution centers substantially reduce energy use. While not new, they continue to grow more sophisticated and affordable.
"They're almost becoming standard, at least for anyone running any kind of refrigerated facility," Hudock observes.
These generally PC-based systems allow operators to set a variety of detailed, conditional parameters to control energy use and provide alerts or notifications when conditions fall outside certain parameters or otherwise require attention.
A lot of their application is in zone temperature sensing and some zone lighting control, Hudock notes.
"The systems allow any types of fans, such as refrigeration or exhaust fans, for example, to be turned on and off based on what's actually happening in the warehouse. In addition to temperature, the system might automatically trigger controls based on doors opening and closing."
Systems are also typically used to provide alerts, such as if a door is left open for a particularly long time, or if the load on the compressors is running higher than normal.
"Any time you can turn off equipment when it's not needed, by automating the controls, you're going to save resources and money. It's all about matching the load with the equipment," Lowery points out.
"As computers have gotten more sophisticated, with more memory, and bigger microprocessors and sensor technology has improved, these energy management systems can now trend components more quickly, and based on more accurate and precise data on conditions," he adds.
The general consensus is that a good energy management system will provide savings of anywhere from 10 or 15 percent to as much as 30 percent or more of a facility's total energy consumption, making some form of automated energy management virtually a no-brainer today.
Every Little Bit Helps
There are many other things companies can do when designing and constructing distribution centers to minimize energy use and other negative impacts on the environment.
"One of the things people are starting to do in new construction is to use more reflective roofing material that doesn't absorb as much heat, especially if they're operating freezer or cooler space. I've heard manufacturers claim such materials can yield a seven to 10 percent improvement in overall energy efficiency. Even if the reality is only two to three percent savings, that can be a pretty significant gain over a building's life," Hudock comments.
"Looking at air movement, even doing something as simple as putting in larger fans to keep air circulating through a facility can help with HVAC costs. And better systems are coming out today that use multiple blowers or fans instead of a single large one, an arrangement that is more efficient and can also be tied into the energy management system, letting you control with more specificity where you need more heating or cooling," he points out.
In an older facility, simple improvements such as making sure you have good dock seals and dock doors can boost efficiency. Likewise, paying a little more for better insulation can play a significant role in reducing a building's energy consumption.