Something as simple as painting the inside walls white can improve lighting effectiveness, reducing the amount of lighting that must be supplied. The way a building is laid out also contributes to its overall efficiency, including energy use.
"A lot of it ties into basic best practices for operations, for reducing labor in general and making efficient use of equipment," Hudock observes. "Simply having items slotted in the right locations to reduce travel time and provide a good, clear traffic flow helps a lot. If people can drive or objects need only move shorter distances in the warehouse you may save a person, a fork lift, a section of conveyor and all the energy each of these would consume."
Similarly, Lowery points out, good preventive maintenance procedures on the refrigeration and other electro-mechanical systems in the warehouse save energy as well as money for repairs and replacement, making the whole facility more "sustainable." Moreover, designing a building's systems to be more part-load efficient and thus more environmentally friendly and economical to run, means the equipment has smaller motors which are less costly to replace when failure does occur, so the approach is a real win-win.
Among the best ways to create an energy-efficient distribution center, in many situations, is to build a high-rise facility equipped with an automated storage and retrieval system.
"We've been involved in projects with ceilings as high as 100 feet, with just eight to 10 aisles of racks. Because the footprint is so much smaller in these vertically-oriented operations, the energy costs related to conditioning the interior are lowered substantially," says Walker. "Moreover, since cranes don't require any lighting to operate, the lighting can be kept to a minimum, only putting in what is needed for maintenance issues, which is another big energy savings."
While the ASRS system consumes some energy, it is considerably less than is depleted by a conventional, horizontally-configured, human operated warehouse, Walker notes.
"The more people you have, the more you have to condition the space," he adds. "Plus you even have fewer people on the road commuting, consuming gasoline and contributing dangerous emissions."
ASRS systems also involve fewer door openings than a traditional warehouse with workers on fork trucks or pallet jacks zipping around, Lowery notes, which helps cut down on the HVAC load.
No matter what type of equipment a distribution center utilizes, there are options within that configuration that can help that operation reduce energy use and improve efficiency.
With conveyor systems, there's a push in newer designs to make greater use of sensor-driven motor technology, so that the belt only operates when product is in the area, rather than running continuously through the entire shift. While the capital investment required upfront for a conveyor system so equipped may run about 20 percent higher, they typically consume from 20 to 25 percent less energy than a system in which all belts are always on during operation, says Hudock.
There are two different approaches to synchronizing belt movement with product movement, he adds. One is through an energy management system, or the conveyor management system installed in conjunction with the conveyor equipment. Since the conveyor picking system operates off optical scan data anyway, it's easy to feed this data into the energy management system, so that product movement through a scan point activates the conveyor motors on the belts in the affected zone.
Another, more localized approach relies on motor-driven rollers. In this case small motors located in each roller typically operate anywhere from an 18- to a 36-inch section of conveyor belt, and simple motion sensors placed at intervals along the beltway detect product on one section and automatically turn on the rollers on the next section for a given period of time.
Which system works best depends on the characteristics of each operation. Those controlled remotely by the conveyor management system cannot be shut off very quickly, and tend to work better with longer run times, since the system is looking at activity in terms of sections, lanes or zones. The equipment-driven solution can turn sections on and off more frequently, an advantage in operations or sections of an operation where product movement is sporadic, rather than organized in large waves or batches.