This multi-phased project extending through 2027 is a Guaranteed Energy Savings Contract for Prince William County Schools (PWCS), the second largest school system in Virginia.
The first phase involves a critical system replacement for Bel Air Elementary School, involving a range of measures that will replace the existing aging HVAC infrastructure with new systems. Bel Air Elementary School currently has an EUI of 90 and indoor air quality concerns. CMTA’s upgrades will turn the 49,800 square foot Bel Air ES into PWCS’ first net zero ready school.
The scope for Phase 1 includes the replacement of the HVAC system with a full geothermal and dedicated outside air system to meet current ventilation standards, significantly improve system efficiency, and mitigate building humidity concerns. The scope of work includes:
- Demolish existing chiller plant
- Remove existing rooftop air handling unit, make-up air unit and exhaust fans, unit ventilators, ceiling cassettes, electric unit heaters and ductless split systems
- Provide a geothermal wellfield with vertical wells, geothermal vault housing isolation vaults, and horizontal distribution piping
- Provide new geothermal water pumps with variable speed drives, expansion tank, air separator and water treatment; new classroom heat pumps, 3 new dedicated outside air units, energy recovery ventilator, geothermal heat pump rooftop unit, vertical heat pumps, horizontal heat pumps, console heat pumps, and kitchen hood make-up air unit
- Demolish existing controls system Provide new web-based direct digital controls system and integrate into existing energy management system
- Implement new control sequences, including optimized building schedules and zone/equipment setbacks Replace ceiling tiles, grid and wall angles
- Replace damaged/missing exterior door weather stripping and sweeps on all exterior doors, and insulate roof/wall seams with spray foam
The second phase involves updating the sequence of operation of select equipment and replacing failed sensors and actuators at 4 facilities with Automated Logic Controls and WebCTRL front ends. This will re-establish proper functionality of the existing equipment while improving occupant comfort and optimizing energy consumption. The schools included in this scope of work are Alvey Elementary School, Battlefield High School, Belmont Elementary School and Freedom High School.
The third phase involves the following for the 145,747 square foot Edward L. Kelly Leadership Center:
- Replace two 225-ton air-cooled chillers and adequately space them to avoid hot air recirculation issues that the current chillers are experiencing
- Upgrade interior and exterior lighting with turnkey LED tube replacements and retrofits, as well as adding dimming switches and occupancy sensors, throughout the building
- Retro-commission HVAC system, consisting of updating the sequence of operation of select equipment and replacing failed sensors and actuators, thus re-establishing proper sensor calibration and controls communication to all equipment; issues identified include static pressure setpoints, airflow rates, improper building pressurization
- Replace the main building controller to take advantage of the full functionality of the Siemens Desigo platform and update the sequence of operations for the majority of equipment, including implementing various controls optimization strategies, such as optimal start, demand control ventilation, integrated economizer, supply temperature resets and static pressure resets
