Updating Fan and Control Technologies in 40-year-old Office Building Reduces Energy Costs 26%
At A Glance
Replacing the heart of an air handling system in a commercial office building with better fan and control technologies can significantly reduce energy costs while dramatically improving equipment uptime. It also goes a long way to reduce maintenance costs and resolve nagging reliability challenges. This is the Blue Cross Blue Shield (BCBS) of Downtown Kansas City, MO story about how it took steps to improve office worker productivity by transforming its air handling systems. BCBS operates in an eight-story office building that is home to hundreds of employees and serves as the headquarters for Kansas City BCBS.
Photo: Example of an old vaneaxial fan, where components like the motor are difficult to service or replace. These fans often require lengthy sound attenuators to reduce fan sound.
Challenge Solution
Air Handler Supplies VAV System
The building’s two air handlers feed a network of variable air volume (VAV) boxes. The system design practice of air handlers having one or two fans was a common approach in earlier decades. Here, the original air handlers were each designed to deliver 80,000 cfm of highly filtered 55°F air throughout the building’s ductwork, and room temperatures were regulated with the VAV boxes and radiant baseboard heat.
In this facility the owner faced two air handler challenges: frequent fan failures resulting in occupant discomfort for several days, and the availability of spare parts to repair the fans. For an office building built to provide a productive environment for hundreds of workers, these issues were a cause for action.
Fan Reliability Caused Major Problems
Don Layne, Operating Engineer with BCBS, commented, “The biggest challenges for us were increasing the reliability and redundancy of the system. We formerly had one supply fan and two return fans. If we were to lose the supply fan, we wouldn’t deliver air to the building. Now, with the FANWALL system, if we were to lose a fan motor, it is a scheduled maintenance item and not an emergency.”
Another problem BCBS faced was high electric energy costs due to the inefficiencies of the old fan system. All of the large fans were required to operate even during periods of light building occupancy and moderate outdoor temperatures.
“At some point, technology updates lead a facility to make a change in order to update and improve their system. Now was our time and a FANWALL system was our solution.”
Seeking Energy Improvements
Layne added, “It had been 38 years that the system operated using the original fans. At some point, technology updates lead a facility to make a change in order to update and improve their system. Now was our time and FANWALL was our solution.”
MMC Contractors engaged Mechanical Sales, a manufacturer’s representative with experienced HVAC professionals that work as solution experts. Marcus Malich from Mechanical Sales was closely involved with this project from the beginning. Before Malich joined the Mechanical Sales team, he worked at the Nortek Air Solutions brand Huntair®, where Malich help advance FANWALL TECHNOLOGY® throughout the industry. His background made him an important asset in finding a solution for BCBS.
Transforming How They Move Air
Mechanical Sales developed a proposed design to replace the DWDI and vaneaxial fans using four FANWALL arrays comprised of modular fan cubes and operated with System Optimization Controls (SOC). The fan arrays and controls were manufactured by Temtrol®, a custom air handling brand of Nortek Air Solutions that specialized in designing equipment for demanding applications. The BCBS facility fit that description.
The FANWALL cubes can be configured to fit any size air tunnel, often requiring up to 50 percent less installation space than vaneaxial fans, and without all of the sound attenuation devices. FANWALL cubes only take up about 3 feet in airway length, whether the application is 5,000 cfm or 500,000 cfm.
Malich points out the particular value of System Optimization Controls. “With SOC we can vary the speed of fans and turn off fans when not needed, which leaves the remaining fans operating near their peak efficiencies. There are tremendous energy savings in operating this way. Each of the motors has its own variable-frequency drive, so if one fan were to become disabled, the remaining fans can speed up to overcome the loss in airflow.”
It was understood that the ideal time to do the air handler changeover was in the winter, when cooling requirements were lower and the four existing fan units could be taken out, one at a time. The contractor selected to execute the project was MMC Contractors, a large mechanical contractor with offices in Kansas City, Houston, Omaha, Las Vegas, and New Jersey.
Equipment
The FANWALL arrays are designed to be installed in a wide variety of configurations. In the BCBS building, the design called for two sets of 12 cubes in a 3×4 configuration within the existing penthouse air handlers on the supply airside, and two sets of 12 cubes in a 3×4 configuration on the return airside.
The FANWALL array retrofit work took place in December 2013 over a two-week window during the holiday. The actual time that was needed to demo the old equipment, rig the new equipment to the roof, install and start up the new FANWALL systems was an astonishing four days. This four-day window also included other air-tunnel upgrades.
“The ease of the modular design allowed us to mobilize much quicker and with less rigging time to help keep the estimate down.”
KEY POINTS
- Facing frequent fan failures, the owner of the Blue Cross Blue Shield office building in Kansas City, MO, needed to replace the fans in two aging air handlers.
- The owner wanted to improve both system reliability and energy efficiency.
- Multiple fan FANWALL arrays were used to replace the existing fans. The solution resulted in significant energy savings and improved system reliability.