Case Study: Automotive Distribution Facility

650,000 Sq. Ft. Heated and Cooled with Only 7 Johnson Air-Rotation® Systems

Customer Automotive Industry
Location Memphis, Tennessee
Building Square Feet 650,000
System Style Indoor, Heating & Cooling
System Size & Qty 7 Johnson Air-Rotation Systems
Savings Over $2 million as a result of equipment and installation cost savings, production
time not lost due to suspension during installation, and utility savings per year.

Design Challenges

The original proposal called for 105 rooftop units to be placed on the 650,000 square foot automotive distribution facility. Due to union procedure, the facility would be shut down for a week during the installation of the rooftop units resulting in substantial lost revenues. In addition, because of the roof penetrations needed to install the rooftop units as well as additional support, the warranty on the roof that was less than a few years old would have been cancelled. The customer was also concerned about maintenance of 105 rooftop units on a regular basis.

Johnson Air-Rotation® System Solution

Johnson’s engineering team designed 7 indoor mounted heating and cooling units that provided the same amount of conditioned air as the 105 rooftop units would have provided. Each Johnson Air-Rotation System has a capability of 90,000 CFM and 200 tons of cooling, while only using (2) 15 horsepower fan motors. The total horsepower of all the Air-Rotation units was 191.1 versus 1,433 the 105-rooftop units would have used.

Project Results

The automotive distribution company was able to keep the warranty on their new roof, avoid the cost of adding ductwork, rooftop support and all the utility connections necessary for rooftop units. In addition, because the Air-Rotation Systems were ground-mounted, they did not have to shut down the facility and the units went up in a matter of hours, not days. The ground-mounted systems also ensured that proper routine maintenance would be followed. Most importantly, the lower total fan motor horsepower used on the Johnson Air-Rotation Systems resulted in electrical savings year after year of $175,376 versus the originally proposed rooftop units!


Original Proposal

  • 105 Rooftop Units
  • 13.65 fan motor horsepower per unit
  • 1,433 total fan motor horsepower used
  • 105 electrical utility connections
  • 105 gas utility connections
  • 105 rooftop penetrations
  • Additional rooftop support needed
  • Ductwork throughout facility
  • Multiple days of the facility closed

Johnson Solution

  • 7 total Johnson Air-Rotation Systems
  • 27.3 fan motor horsepower per unit
  • 191.1 total horsepower used
  • 7 electrical utility connections
  • 7 gas utility connections
  • 0 rooftop penetrations
  • No additional rooftop support needed
  • No ductwork
  • No closure of the facility needed

Fan Motor Horsepower Calculations for Automotive Distribution Center

Elimination of 105 rooftop units will save the company $175,376 per year.

Johnson Air-Rotation Capabilities

  • The Only UL Listed Air-Rotation System
  • Reduces Cost on Equipment, Labor, Operation
  • Cooling Throw – 275’
  • Heating Throw – 325’
  • 150,000 Square Feet with a Single Unit
  • Up to 6,250 MBH Per Heating Unit
  • Up to 450 Tons Per Cooling Unit
  • Up to 170,000 CFM Per Unit