Efficiency, lower costs, and optimization strategies are the focal points of today’s energy landscape. Energy efficiency is a way to improve business performance and reduce unnecessary waste.
Routine and preventative maintenance is a low-cost
way to achieve the greatest return on investment in
systems. Following are two case studies that demonstrate the impact a solid facility maintenance program
can have on energy use and the bottom line.
Case study #1
The scenario: A large institutional facility was experiencing multiple problematic systems, including multiple air handler units that weren’t functioning correctly.
The units were taxing energy consumption and
increasing costs. Based on an early check of the pressure controls and instrumentation, the facilities staff
did not identify any critical concerns. However, the
units were not maintaining adequate riser duct static
pressures, despite the fact that the variable frequency
drives (VFDs) in many of their fans were operating at
The diagnosis and results: The Facilities Forensic
Examiner began using the least intrusive methodology. The eight return fans and 12 supply air fans were
shut down for inspection. The findings: The protective screens at the inlet and outlet of the fans had
become clogged with a significant build-up of carbon
and fibrous materials. The screens were cleaned and
vacuumed. When the systems came back online, the
static pressure control improved substantially. Many of
the fan VFDs had modulated below 100 percent VFD
speed, and most of the risers were maintaining or
nearly reaching their static pressure set points.
The payoff: Cleaning all the supply and return
fan screens took two people eight hours, at a cost of
approximately $400. Based on energy calculations
related to the eight return air fans alone, simply cleaning the fans had reduced horsepower demands by the
equivalent of 135.6 hp. The immediate savings to the
bottom line: $267 a day — a payback of 1.5 days on
the cleaning effort.
Lesson learned: Avoid deferred cleaning cycles.
Fan horsepower demand will gradually increase over
time. Schedule cleaning tasks based on your environment, and always collect before and after measurements to validate performance changes and energy
Case study #2
The scenario: While design standards provide optimal efficiencies for establishing a baseline of operation, the most forward-thinking owners want to protect their financial investment by ensuring systems are
configured from inception to function as designed.
An independent commissioning process can provide
Following extensive facility renovations, a testing,
adjusting, and balancing (TAB) contractor reported
marginally acceptable tolerances of airflows from a
make-up air unit (MAU) serving the building’s kitchen. The Facility Forensics Examiner reviewed the air
balancing report, and determined the fan, despite
operating at 60 Hz on the variable frequency drive or
100 percent of its rated speed, was functioning below
its designed air flow capacity.
The diagnosis and results: Not unusually, portions of the building’s ductwork had been reused
during the renovations. The Examiner investigated the
installation of both the new and existing ductwork,
where he discovered a pneumatic isolation damper
for the old MAU hidden deep within the existing
ductwork, long forgotten by the facility staff. The
damper’s actuator was damaged and was positioned
about 25 percent open, substantially restricting airflow
through the ductwork.
The facilities staff secured the damper in an open
position and ordered a replacement actuator. The
fan was later rebalanced, and its operating speed on
Surfacing the Hidden Pitfalls in
Existing Conditions and Renovations
Greg Burgess, CxA,
CEM, LEED AP
Removing a build-up
of carbon and fibrous
materials clogging the
protective screens of eight
return air fans reduced
horsepower demands by
the equivalent of 135.6
Hp. Deferred cleaning
cycles translate to lower
equipment efficiency and
higher operating costs.