2008-11-07 - ABB variable speed drives have cut energy consumption by 50 percent at 50 McDonald’s restaurants in the United Kingdom. The drives have also reduced noise emissions and improved equipment efficiency in the kitchens.
By ABB Communications
The ABB standard drives for heating, ventilation and air conditioning (HVAC) applications have reduced the power consumption of kitchen extractor units by half at 50 of the fast food company’s U.K. restaurants.
“We were updating old equipment and realized we could reduce our carbon footprint by making large fans run more slowly,” says Dave Holden, project manager of McDonald’s Restaurant Services.
“Variable speed control gives us the extraction volumes we need while cutting energy use.”
- Dave Holden, project manager, McDoanald’s.
The drives control the speed of fan units with large 5.5 kW motors. These now draw about 2 kW, but have the capacity to boost extract volumes significantly at busy times.
“Reliability coupled with a fit-and-forget setup was essential,” says Holden. “Our managers work incredibly hard running successful restaurants and do not want to be troubled with technical equipment unnecessarily.”
Prior to the installations McDonald’s were hoping that the drives would achieve 40 percent energy savings, soft startup and less wear and tear on the fans. The solution was provided by Inverter Drive Systems (IDS), a U.K. member of ABB’s global Drives Alliance network.
Quietly saving a bundle
Using the drives’ real-time clock, IDS set the fans to run at full speed during busy periods and at 80 percent at other times. This resulted in a 50 percent saving in energy consumption. Another major benefit of the drives is the reduced fan noise, which is particularly important to McDonald’s at night.
“The average 50 percent saving in electrical consumption was even greater in restaurants that had oversized fan motors from the 1980s.”
Enabling the fans to operate at lower speeds has improved the performance and energy consumption of cooking equipment by solving a problem caused by extracting high levels of air (and cooking smells) in the kitchen.
High extraction rates created an imbalance in the air conditioning system which led to a rush of cold air entering the kitchen whenever an external door or window was opened. This caused the equipment to work harder and use more energy as it attempted to maintain the cooking temperature. Reducing the fan speed with the drives has alleviated this.
“As well as reduced utilities costs, we now have fewer operational difficulties with the kitchen equipment as a result of being able to balance the extract volume,” says Holden.