Planning for sustainable development starts with analyzing the requirements and realities of each business. For warehouses and distribution centers, the issues are less complex than with manufacturing operations, but that doesn't mean there aren't significant opportunities to conserve resources and become more efficient.
Hudock says that when addressing environmental concerns with warehouse clients, there are three primary areas Tompkins discusses:
- Facilities design;
- Equipment and equipment controls;
- Packaging, in terms of how product is handled and moved throughout facility.
"Among the first and easiest things to do is to address lighting in the building," he adds. "We try to use as much natural lighting as possible."
Increasingly, distribution centers are incorporating skylights to take advantage of sunlight. For companies that are concerned about roof penetration, sidelights—windows mounted high on the walls, just below the ceiling—offer most of the same benefit, Hudock notes.
Jud Walker, a LEED-certified engineer with Stellar, adds that companies are installing sensor controls to work in concert with skylights. The sensors detect the amount of ambient light coming through and automatically adjust the electric lights accordingly.
Companies can also install motion sensors to control lighting in different areas of the warehouse, so lights are only turned on when someone enters or accesses that area.
"These are especially effective for limiting unnecessary lighting in large storage areas deep in the warehouse," Hudock points out.
In terms of lighting technology, there has been a big push recently to develop fluorescent lights that are suitable for warehouse operations.
"With traditional, high-density warehouse lighting there's approximately a 10 percent energy loss. With fluorescent lighting, there's no energy loss," Walker notes.
The downsides of fluorescent fixtures are their lack of "quick-strike" capability, i.e. it takes time for them to turn on; as well as their inability to function in low-temperature environments.
Although temperature barriers remain, newer fluorescent technologies have recently been introduced that allow fast starts, making fluorescent lighting a good option for many dry warehouse facilities, even where motion sensors are used to turn lights on only as needed.
Walker says lighting manufacturers are also developing better ballasts for high-density lamps with less energy loss. However, presently these fixtures are still quite new and therefore expensive.
Another key consideration are the heating and cooling systems, especially for DCs operating any sort of cold storage, Hudock notes.
Of necessity, refrigeration systems are designed with sufficient capacity to operate effectively under the most demanding conditions, on the hottest day. The key to economizing lies in a system's ability to match output with load, or what is known as "part-load efficiency," Lowery explains. In other words, how efficient is the system during periods of lower demand; how much less energy does it consume when conditions do not require it to run full bore?
"To do that, you need systems that can be controlled in ways that closely match demand, so that whenever they're operating, they're operating at 100 percent efficiency," Lowery notes.
One way to save on energy with refrigeration systems, as well as with any other motor-driven systems, including other HVAC applications, conveyor systems, and automated doors, is by specifying premium efficient motors, Walker comments. They cost more upfront but typically pay back the extra investment through lower energy costs within 18 to 36 months.
Variable frequency drives on compressors and other motors—a relatively new technology, the use of lower horsepower evaporators combined with larger refrigeration coils and systems designed to operate with lower condenser pressure are other easy-to-justify investments in part-load efficiency that can pay off for themselves fairly quickly—generally within two to three years, Lowery adds.
"When we work on refrigeration projects we typically look at total economic value, which means finding the correct balance between initial cost and ongoing energy consumption and payback," he comments.