April 20 Times story on geothermal field
The geothermal bore field design includes 192 vertical bores at 500 feet deep. This field will support the 308 tons of heating and cooling required for the new facility. The College earlier installed one bore to evaluate the field conditions and soil conductivity.
The closed-loop geothermal system design includes (30) water-cooled modular VRF heat pump units with associated (131) VRF fan coil units, primary loop water pumps, a vertical well geothermal bore field and associated piping. The basis of design is the Daikin VRV-WII system. The system offers the ability to match the building load precisely with variable capacity through the use of inverter compressors. The system offers two stage heat recovery; first between the various zones of the heat pump and second through the common closed water loop. The heat pumps are located in a second floor mechanical room with the zone fan coil units distributed throughout the building.
A whole-building energy model has been completed for the building using Trane Trace 700 software. This model includes information about the expected occupancy of the facility and expected weather conditions for the local area throughout the year.
As part of the College’s commitment to sustainability and as a requirement of the Capital Development Board, this new facility is targeting LEED Silver Certification as outlined by the U.S. Green Building Council (V3.0). In addition to the incorporation of a closed-loop geothermal system into the overall building design, following is a list of other energy-savings strategies that will be utilized in the new facility:
- Dedicated ventilation units cycled with occupancy
- Energy recovery on air handling units
- Variable volume loop water pumps
- High efficiency condensing hot water boilers
- High efficiency domestic water heating system
- Variable frequency drives for motors
- High efficiency light fixtures
- Daylight harvesting sensors
- Multiple switching zones to allow occupants to vary lighting levels
- Thermally efficient glazing
- Reflective white roofing membrane
- Fundamental Commissioning
Current energy modeling of the new building including all of the above design features indicates that the building’s energy performance will be approximately 37% below the ASHRAE/IESNA Standard 90.1-2007 Appendix G baseline requirements. Additionally, all information identified on the Model Geothermal System 2011 Application Form as submitted with our Letter of Inquiry has remained the same. The combination of all of these energy efficient design features will clearly result in a high-performance building meant to serve as a model for sustainability for the College as well as the entire District 513.