As the prime consultant, BKM provided MEP design services for the systemic renovation to the 70,190-square-foot Chapel Hill Elementary School in order to upgrade the entire facility’s existing HVAC systems and provide air conditioning systems.
The mechanical design featured an air conditioning system consisting of a two-pipe unit ventilator/fan coil unit system utilizing a new air-cooled chiller (mounted on grade in an acoustical enclosure) and the existing hot water boilers. Ventilation, in accordance with ASHRAE 62, is provided through new rooftop DOAS units. The new air-cooled chiller (premium efficiency type) is located at grade level and provided with an acoustical enclosure to meet the local sound ordinances. New dual temperature pumps were provided with variable frequency drives to conserve energy.
New dual temperature piping was provided and connected to new unit ventilators in each classroom. Two control valves were provided to each unit ventilator. Two position, two-way valves were provided on the dual temperature supply pipe to each terminal unit (fan coil, unit ventilator, cabinet heater, etc.) to open when the temperature of the dual temperature water is above 90 degrees and closes when less than 90 degrees. A modulating two-way valve was provided on the dual temperature return pipe to each terminal unit and modulates as required to maintain heating set point for the thermostat. The media center, and gymnasium is all conditioned by dedicated rooftop air handling units. Dual temperature piping was extended to unit ventilators which provided the heating and cooling for the cafeteria. The administrative areas and nursing suite are heated and cooled by a VRF system. New roof mounted DOAS units with enthalpic plate heat exchangers provide ducted ventilation air to each classroom. The kitchen is tempered by a dedicated VRF system mounted in the ceilings.
Electrical work included power, lighting, and fire alarm system design. Approximately 80 percent of existing interior lighting was replaced with new energy efficient light emitting diode (LED) type lights and associated central control system compliant with current energy codes. Power system design included evaluation and replacement of the existing utility service entrance required to support proposed HVAC modifications. Power system design also included the installation of new distribution system equipment to support proposed HVAC and lighting modifications. Emphasis was placed on reusing major electrical infrastructure as much as possible to help reduce project construction cost. The building fire alarm system main panel and associated components was replaced and new devices were provided for the new HVAC equipment.