LOCATION
Iowa City, Iowa

AREA
30,148 GSF

PROJECT DESCRIPTION
Longfellow Elementary is a 100-year-old building that is undergoing modernization renovations and an addition to accommodate a new main entrance, media center, art room, music room, and gymnasium. An elevator will be installed along with a geothermal heating and cooling system.

PROJECT HIGHLIGHTS

• Vertical, self-contained, geothermal water source high efficiency heat pumps with individual space control are utilized to provide space temperature control in each classroom. Support spaces use horizontal, geothermal water source high-efficiency heat pump located above ceilings.
• A horizontal bored geothermal loop field was installed. Fifty-two 600-foot-long horizontal bores were installed to minimize disruption of the existing school site. Emergency backup heat for the ground-coupled heat pump loop is provided using an electric boiler.
• Code required outside air for the ground-coupled heat pump system is provided by three energy recovery units. The units include direct expansion cooling and hot gas reheat to dehumidify outdoor air and an electric heating coil to prevent frosting on the energy recovery unit heat transfer surface during extremely cold ambient air temperatures.
• Code required lighting control systems were provided for interior lighting that incorporate vacancy sensors, occupancy sensors, manual dimming, multi-scene control, an automatic daylight harvesting where natural daylight is present. The interior lighting design proved to be 78% more efficient than the baseline code energy allowance and the exterior lighting design proved to be 91% more efficient.
• Exterior lighting was controlled through a dusk-to-dawn exterior photocell wired in series with a programmable timeclock within the building automation system. Exterior parking lot lighting includes bi-level control, allowing the district to reduce parking lot luminaires to 50% when desired through the building automation system.
• Energy saving strategies:
  • Energy recovery unit zoning allowing shut off when areas are unoccupied.
  • Specifying heat pumps with efficiencies above minimum code requirement.
  • Energy efficient LED luminaires with soft diffusing optical lenses and reflectors throughout the building interior and exterior.

Photography credit: Kessler Photography