Century Middle School
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Project Summary
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Adams Twelve Five Star Schools
Thornton, ColoradoProject Type:
Existing Building Retro-Commissioning
Size:
116,000 Square Feet
Year Occupied:
1998
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Project Details
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Century Middle School opened for classes in the Fall of 1998. The building was targeted for retro-commissioning by the school district energy manager based on a high energy utilization index ($/ft2/yr), and numerous occupant complaints on comfort. The reasons for high energy use and unsatisfactory comfort conditions included poor control of the mechanical systems and broken mechanical devices.
Architectural Energy Corporation (AEC) completed retro-commissioning services in March 2002. Commissioning services were focused on improving the performance of the mechanical systems, reducing energy consumption and increasing occupant comfort.
Project Highlights
Diagnostic testing performed, problems identified, repairs and building automation system sequence fixes made, performed pre-functional and functional performance testing. HVAC system is constant volume with reheat, boiler plant and chiller plant. Building automation system is Control Systems International (CSI).
Targeted large systems including AHUs, Boiler plant, Chiller plant. Then identified zone problems and occupant comfort issues. After completion, occupant comfort complaints have been reduced substantially and the gas energy savings is close to 46%, and electrical kWh savings is 22% from previous years.
Partial list of problems identified and fixed (32 total):
- No hot water present to 2nd floor classroom reheat coils.
- Hot water supply temperature reset control not functioning
- Six AHU hot water valves full open during unoccupied hours, resulting in a large heating load on the boilers
- Equipment schedules were 4 hours longer than necessary per day
- AHU systems control to constant 55(d)F discharge air temperature all year (without proper reset strategy), thus increasing cooling loads, and reheat loads
- Numerous AHU valve and damper actuators broken, and all pneumatic transducers improperly configured
- Minimum outside air fractions never properly programmed into building automation system
- AHU exhaust plenums over-pressurized with exhaust fan running and all dampers closed
- Building and crawl space static pressures always negative to outside air
- Chilled water supply temperature reset not programmed
- Chiller enabled when airside free cooling should have been utilized
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