DC Velocity - June 2012

That means those doors are open a large part of the time, and open doors invite in cold air in the winter, hot air in the summer, and snow or rain whenever they occur.

Over the past two years, the shipping area has substantially reduced its energy use and heating costs as the result of a switch from natural gas heating to steam as well as two investments at and around the dock doors.

Kutney says the dock door project arose out of a push to improve dock safety. He says a conversation about dock locks and safety with dock equipment specialist Rite-Hite led to a discussion about ways to seal dock doors in order to reduce energy use.

The effort had two major parts: one directly addressing the dock doors, the second using fans to recapture heated air from the ceiling.

At the doors, the goal was to create tight seals to prevent energy loss while the doors were in use. To achieve that, Kutney selected a group of complementary dock shelters and dock leveler pit seals from Rite-Hite.

A major source of heat loss at dock doors is the gapping that occurs between a trailer’s swing-out doors and the trailer sides when the doors are open.

According to Rite-Hite, the two-inch gaps along the hinges equate to a two-and-a-half-foot hole in the wall. That allows a lot of cold air to enter and warm air to escape in Milwaukee’s often-frigid winters.

MillerCoors replaced its existing dock seals with a dock shelter called the Eliminator-GapMaster II from Rite-Hite’s Frommelt line of products. The soft-sided shelter features polyethylene hooks on its side curtains that seal those trailer door hinge gaps when a trailer is backed into position. At the same time, it creates a seal around the trailer tops and sides without impeding lift trucks’ access to the trailer.

Another source of energy loss at MillerCoors’ docks was through the steel decks of the dock levelers. To seal those areas, MillerCoors installed PitMaster Under-level-er Seal components, also a Frommelt product. Rite-Hite says the product seals gaps where the leveler, trailer, and dock shelter meet—essentially the fourth side of the door opening. It also creates a pocket of air beneath the

leveler, which acts as an insulating barrier to reduce heat transfer through the leveler deck.

MillerCoors also installed weather seals to close off gaps between the sides of the leveler and the pit walls.

FANS BRING DOWN THE HEAT

In addition to plugging leaks at the docks, Kutney asked Rite-Hite to address an issue common to distribution centers in areas with cold winters: heated air rising to the ceiling. Rite-Hite says that air temperature in a typical DC will be one-half to 1 degree F warmer for every foot in height when air is not circulated. That drives up heating costs as heating systems struggle to warm air at floor level. Kutney says the temperature at the ceiling level in the shipping area was as much as 20 degrees warmer than at floor level.

MillerCoors installed three 24-foot high-volume, low-speed (HVLS) fans from Rite-Hite in the dock staging area. Rite-Hite says the fans work by forcing warm air down toward the floor, where it mixes with cooler air and eventually rises again, only to be pushed down once more in a process called destratification.

According to Rite-Hite, the shipping center saw its natural gas costs drop by $70,000 in the first 18 months after the installation of the seals and fans.

Although costs have continued to decline, Kutney notes that the company has since replaced its overhead gas-powered dock heaters with more efficient heaters powered by steam, so it’s difficult to say how much of the further savings can be attributed to the seals and fans alone. Nonetheless, he says he’s confident that MillerCoors recovered its investment within two years, a full year faster than anticipated.

Furthermore, the seals and fans have created a much more comfortable environment for workers, he says. The docks are warmer in the winter, and the fans provide some cooling in the summer.

In addition, he says, the seals keep the dock area dry during wet weather, making operations safer.

All in all, Kutney says he’s pleased with both the savings and the improvements in the work environment from the investment. “It’s paid off in a lot of ways,” he says. ;