Improving Energy Performance through Retro-Commissioning:
"Weighing the Pig" vs. "Making it Fly"
Timothy P. Pennock, PE, GRG, Inc.
Many energy management programs are administered by staff that
does not understand how the building energy consuming systems actually
work. They spend a lot of time and energy "weighing the pig"
on a regular basis by measuring energy consumption. A different
skill set is required to actually interrogate the performance of
the HVAC systems and improve operation to reduce energy performance
and actually "make it fly."
Commissioning Professionals have a broad skill set which encompasses
design, installation, set-up, sequences of control, operation, optimization,
and maintenance of HVAC systems. These skills allow the Commissioning
Professional to quickly identify hidden underperforming systems
and realize immediate energy savings.
Retro-Commissioning existing laboratory building HVAC systems
usually results in a minimum energy savings of 10 percent. HVAC
systems in air-driven laboratories consume large amounts of energy
in pre-heating, cooling, re-heating, humidification, dehumidification,
and pressurization processes. Control system setpoint adjustment
of just one degree in air temperature, or a few hundredths of an
inch of pressure can affect energy consumption by tens of thousands
of dollars per year.
We will present lessons learned from Retro-Commissioning laboratory
and healthcare facilities and their economics. We will demonstrate
through specific examples of common hidden system failures how a
1,000 percent payback is possible. Facility managers can use these
techniques to improve the energy performance of their existing buildings.
There is a far greater opportunity for industry-wide energy savings
in the multitude of existing lab buildings than there is in designing
new buildings according to energy efficient principles. An experienced
Commissioning team is one of the few resources available to laboratory
facility owners who can:
- Reverse-engineer the design intent of the systems,
- Evaluate system performance based upon fundamental psychrometrics,
- Evaluate control system logic,
- Identify hidden control device failures, and
- Adjust setpoints immediately to save energy savings.
Four hours of Retro-Commissioning of a 60,000 cubic feet per minute
university biological laboratory discovered four hidden air handling
unit operational problems that resulted in over $100,000 of unexpected
Two hours of Retro-Commissioning of a 250,000 square foot hospital
facility discovered hidden failures with the pneumatic spring return
open chilled water valve actuators on eight air handling units.
Identifying the hidden problems with these valves had a two-fold
benefit to the owner. First, they saved over $100,000 in unnecessary
overcooling and reheating energy costs. And second, they were able
to defer a chiller plant expansion project that was not in their
capital budget for a small data center renovation because Retro-Commissioning
reduced the cooling load on the chiller plant by almost 150 tons.
Tim Pennock oversees the Commissioning Services
group at GRG and has 20 years of experience in the building industry,
and 5 years of commissioning experience. He is responsible for commissioning
over 100 projects. Tim has also provided Retro-Commissioning (CxR)
Services for over 30 existing buildings. He earned a BSME and MBA,
is a registered Professional Engineer in several states, is a LEED™
2.0 Accredited Professional, a QCP™ Qualified Commissioning
Process Provider, and is a Certified Commissioning Authority through
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