Greenwood Elementary School HVAC Replacement & Commissioning

Gipe Associates, Inc. conducted an HVAC Scope Study for the Greenwood Elementary School in Princess Anne, Maryland. The original school was circa 1961 with additions put on in the mid-90s. Many of the MEP systems were original to the school and were approaching the end of their useful service life.

A full evaluation was completed for the mechanical and electrical systems.  Our engineering team performed field surveys, preliminary load calculations, and documented code compliance issues.  A 30-year life cycle cost analysis was completed to compare three HVAC System options.  The existing electrical service primary and secondary voltages were verified and evaluated for adequacy for proposed HVAC upgrades.  Recommendations included replacement of the HVAC system with an energy efficient geothermal system and new branch circuit panelboards.

Gipe Associates acted as the Prime Design professional to Somerset County Public Schools for the design of the recommended systems noted in our report for Greenwood Elementary School project.  The design effort included heating, ventilating, air conditioning, and power systems design.  The chosen HVAC system was a Geothermal/ Variable Refrigerant Flow System. Indoor units consist of the same components as most water source heat pumps.  The complete refrigeration system, including compressor, water-cooled condenser, direct expansion cooling coil, expansion device, and refrigeration controls are housed in each unit.  Additionally, a supply fan and filters are also components of the unit.  A reversing valve located in the refrigeration circuit allows the unit to provide heating or cooling, but not both simultaneously unless an optional hot gas reheat coil is added for dehumidification control.  For areas where humidity control (classrooms) is required we specified geothermal heat pumps with hot gas re-heat coils.  This allows full dehumidification with re-heat energy being provided by waste heat, not an external fuel source.

Units were provided for each zone such that individual zone control can be accomplished.  These units were connected to the water source heat pump loop. Two (2) way, two (2) position ATC valves shall be utilized to reduce system flow when a unit is de-energized by its room temperature sensor. To prevent over pressurization of the loop a differential pressure sensor and flow measuring station shall modulate the speed of the central distribution pumps.

The water source heat pump units primarily constructed to be the re-circulating air type do not have sufficient capabilities to condition the ventilation requirements associated with the spaces.  Therefore, separate Energy Recovery Ventilators with heat wheels designed specifically for the conditioning of outside air were implemented.  These units, operating at 100% outside air, were ducted directly to each space to comply with current ventilation requirements.   

The energy recovery ventilators were provided with variable frequency drives and demand controlled ventilation.  The ventilation system monitors the carbon dioxide levels and allows the ventilation system to reduce airflow rates when the occupancy and carbon dioxide levels allow.  Unlike conventional water source heat pumps, the circulating fluid can be very cold; and due to these extended temperatures, all piping was specified to be insulated. No central boilers, chillers or cooling towers were required for this system.  Water source heat pumps with built in energy recovery wheels were provided for all classrooms.

As the prime consultant Gipe Associates was responsible for coordinating work between the architect, other design consultants, and construction manager while taking care to meet the needs and requirements of the Owner.  Gipe Associates conducted & documented meetings, and performed inspections during the construction process. 

Project Type: K-12,