How Federated uses fans to further sustainability
April 01, 2012 - MMH Editorial
With the cost of heating the Saskatoon warehouse going through the roof—literally—Federated Co-operatives was interested in testing whether thermal destratification in its warehouses would result in significant heat cost reductions and the reduction of the amount of natural gas needed to heat its facilities. Destratification is what happens when layers of warm air that form in one part of a facility mix with layers of cooler air in another part of a facility to produce a constant temperature.
According to Trevor Carlson, environmental and technical services manager, Federated believed a fair amount of heat was being trapped or lost through the ceiling. The difference between the temperature of the air at the floor level and the underside of the roof deck in some distribution centers can be up to 30 degrees, depending on the time of year. If that warm air could be brought down to circulate through the building, then Federated could reduce the rate at which its buildings were shedding heat through the roof.
To put the theory to the test, Federated installed five 24-foot large-diameter, low-speed fans (Big Ass Fans, bigassfans.com) in the 80,000-square-foot loading dock area back in 2007. The retail co-operative then began to measure its heat index in the pilot area, a measurement that relates the day’s temperature to the energy demands of the heating system. The index is expressed as Btu/ft2/degree day. Before the installation of the fans, the heat index was 4.49 Btu/ft2/degree day. By the end of 2008, the heat index had been reduced by 10% to 3.61 Btu/ft2/F.
Since then, Federated has expanded the use of fans to other facilities, says Philip Thiemann, warehouse operations director. In Winnipeg, for instance, the co-op installed a fan in a temperature controlled dock area where hot air was building up in the hot summer months around the dock doors.
“We had to turn the thermostats down, which put a constant demand on the refrigeration units,” he says. “The air movement from the fans allows the air to mix and even out the temperatures.” In the process, Thiemann adds, workers have found that the new fans keep the ambient temperature areas more comfortable on hot days for less money.
“The big fans use about 3 amps an hour compared to 180 amps for the fans we had been using in the summer,” he says. “The electrical savings in the summer are greater than the gas savings in the winter and the workers are more comfortable.”