Beth Israel Deaconess Medical Center | Chestnut Hill Square Medical Office Building
The new, spacious Chestnut Hill location features walk-in urgent care as well as primary care and a variety of outpatient services including sports medicine and rehabilitation, obstetrics and gynecology and medical imaging.
SCOPE OF WORK:
Fitzemeyer & Tocci was contracted by Beth Israel Deaconess Medical Center to provide commissioning services for a 30,000 sf tenant fit-out of a mixed use medical office space. The project consisted of a complete interior tenant fit-out which included all mechanical, electrical, plumbing and life safety systems. Systems commissioned included variable air volume (VAV) and constant air volume (CAV) boxes, ductless split air conditioning units, exhaust fans, humidifiers, radiant heat panels and the addition of an air flow metering station for the rooftop unit.
CHALLENGES:
Functional testing of terminal units revealed that some of the design sequence of operations could not be achieved with the equipment installed. Some spaces in the building were designed with constant air volume (CAV) terminal boxes with carbon dioxide sequences. The original design intent for the spaces with CAV boxes and carbon dioxide control sequences was for the terminal box volume damper to modulate open when the carbon dioxide reached its high limit. The constant volume boxes could not modulate their dampers according to the sequence.
Some spaces were also designed with VAV/CAV boxes with both hot water reheat valves and radiant heat panels. The provided sequence of operation was to modulate both valves simultaneously in order to maintain the space temperature setpoint.
Numerous issues were found with the pairing of the supply and return VAV/CAV boxes on the project. The terminal box schedule in the construction documents was a general VAV/CAV box schedule that left the pairing of the boxes to the ATC contractor’s discretion. The pairing of boxes was done geographically and not according to the zones they served, resulting in instances of improper pairing of supply and return units.
SOLUTIONS:
The CAV boxes with carbon dioxide control were discussed during the controls integration meeting in order to determine the ability of the CAV boxes’ execution to the carbon dioxide control. The commissioning team coordinated with the unit manufacturer to determine the capabilities of the existing roof top unit and revised carbon dioxide sequences of operations in order to accommodate the current orientation of constant volume supply terminal boxes.
The controls integration meeting held by the commissioning team early in the construction phase of the project vetted the radiant panel valve types and developed the staging sequences that needed to be implemented by the ATC contractor.
The pairing of the supply and exhaust VAV/CAV boxes was driven by the commissioning team to ensure proper pairing of the equipment. The Fitzemeyer & Tocci commissioning team has since implemented a more detailed pairing review of both supply and return boxes to be done during the design review phase of the project to prevent improper pairing of units on future projects. Fitzemeyer & Tocci encourages commissioning for all of your new construction or renovated projects. The fees associated with commissioning (or retro-commissioning of an existing facility) are offset by reduced energy costs, improved occupant comfort and productivity and reduced change orders. In addition, the owner benefits from significantly lower utility, operations and maintenance costs.