The St. Mary’s County Board of Education has approved the design of improvements to Greenview Knolls Elementary School including replacement of its aging heating and air conditioning system. The design will now go to the state for final approval. Estimated cost is more than $3 million.
Greenview Knolls was originally built 1965 with additions in 1971, 1990, 1997 and 2009.
According to Supervisor of Design & Construction Larry Hartwick the school’s low ceilings presented a design challenge for the system. Instead of a conventional chilled water cooling plant or volume distribution system the design uses what is known as a Variable Refrigerant System (VRS) in the classrooms.
According to Hartwick’s report to the school board, the VSR is composed of “roof-mounted heat pumps that distribute refrigerant to ceiling mounted units in the classrooms. During the heating season, the heat pump cycle is reversed and warm refrigerant is pumped to the interior units for heating. Dehumidification and ventilation requirements are handled by dedicated outside air units using conventional roof top units.” The existing oil fired boiler will be replaced with a more energy-efficient gas boiler.
The VSR systems were developed in the 1980s. Hartwick assured the board members that other school systems have used the process with positive results. “They are very pleased with the performance,” he said, adding that replacement parts are available locally.
The bid for construction of the improvements will include several alternatives, including.
· Replacing all of the exterior windows in the 1965-1990 areas with high performance windows.
· New lighting and acoustical ceilings since the ceilings and lights will have to be removed to put in the HVAC system.
· Replacement of existing pneumatic building controls with digital controls.
· Removal of an existing underground oil tank.
Hardwick said it is anticipated that construction will be accomplished over two summers so classrooms won’t have to be disrupted. Construction bids are expected to be let in March after approvals from the state’s Public School Construction Program.
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