Parkway West High School Retro-Commissioning Project and HVAC Maintenance Improvements

BACKGROUND

Parkway West High School is one of five high schools within the Parkway School District and has a student population of approximately 1,260. The school conducted a retro-commissioning study due to its low performance and occupant discomfort that produced suggested performance and indoor quality upgrades. After building improvements, the project is expected to result in an annual energy savings of 15 percent and an annual cost savings of $55,000.

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The district portfolio includes 28 K-12 schools and serves approximately 17,300 students within the western suburbs of St. Louis, Missouri.  The district has two dedicated early-childhood education facilities and four additional support buildings. Parkway West High School was constructed in 1967, comprising 317,000 square feet of space that includes three gymnasiums, a swimming pool, an auditorium, cooking facilities, and outdoor athletic fields.

The school's last major HVAC upgrade was completed in 1999 using an energy savings performance contract.

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SOLUTIONS

The district worked with the school to select a vendor, conduct a detailed retro-commissioning study, apply for utility incentives, and implement adjustments to the building’s air handling units, water valves, and controls. 

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Below is a chart of implemented measures along with associated costs and estimated annual energy savings.

 

Savings Measure

Cost

Savings Achieved

Details

Supply air temperature reset control (from 50F to 55F-60F)

$12,886

162,460 kWh

Resetting air handling unit discharge air temperatures upward when conditions allow, reduces cooling and reheat energy required

Duct static reset

(4 fans, 4,627kWh each; decrease static pressure 0.5", flow by 25%, HP by 1.83)

$1,920

18,508 kWh

Adjust static pressure of variable air volume boxes (VAV) based on air flow across zones

Economizer optimization (4 air handling units, 3 rooftop units)

$13,170

117,290 kWh

Increase outside air into the air handling unit when enthalpy is lower than return air enthalpy

CO2 controls 2 air handling units; 1 rooftop unit

$8,039

68,267 kWh

Balance minimum outside air set points with required ventilation

3-way chilled water valves, balancing of chilled water system

$29,592

58,796 kWh

Improve valve functioning to enable variable flow drives (VFDs) on the pumps to meet system pressure set points

Hot water control balancing

$4,841

19,648 kWh

Replace differential pressure sensor to adjust system flow, thereby reducing pump speed

 
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OTHER BENEFITS

Parkway secured a utility rebate totaling $39,200, reducing the overall project cost to the district by 30 percent. In addition, the district implemented a number of HVAC maintenance improvements such as removing inlet guide vanes and installing new inverter duty motors and associated VFDs, among other measures. These measures are expected to improve the overall performance of the building and increase comfort while yielding a small amount of energy savings.

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Annual Energy Use

Baseline (2015)
163 kBtu/sq.ft.
Expected (2018)
138 kBtu/sq.ft.
Actual (2018)
Coming Soon

Energy Savings:

15%

Annual Energy Cost

Baseline (2015)
$369,000
Expected (2018)
$314,000
Actual (2018)
Coming Soon

Cost Savings:

$55,000

Sector Type

Education

Location

Chesterfield, Missouri

Project Size

317,000 Square Feet

Financial Overview

$127,000

Entrance to Parkway West High School
Entrance to Parkway West High School