Illinois Air National Guard 126th Repair Squad Operations Facility

Project Summary

The Illinois Air National Guard 126th Repair Squad Operations Facility, at Scott Air Force Base in Illinois, serves full- and part-time staff of the 126th Air Refueling Wing and active-duty personnel of the U.S. Air Force 906th Refueling Squadron, which are integrated through the Total Force Integration initiative. Hanson provided planning, design and construction-phase services for mechanical and electrical renovations to the 17,413-square-foot facility, revising the floor plan to more efficiently use the space and incorporate more open office areas. Hanson also participated in a design charrette and feasibility studies for geothermal heating, ventilating and air conditioning (HVAC), solar photovoltaics and solar domestic water heating.

Prior to the team’s involvement on the project (including Bailey Edward Design as the team lead and project architect), a consultant evaluated options for the floor plan changes to determine if converting the HVAC system to geothermal would be feasible. The consultant concluded that converting the boiler chiller variable air volume (VAV) system to geothermal would cost $1.2 million more compared to rezoning the VAV and replacing the boiler and pumps.

Subsequent to that, Hanson created a new energy model to run another geothermal feasibility analysis for the selected systems. Through a variety of strategic changes, Hanson was able to improve the efficiency and reduce the cost of the geothermal option presented by the previous consultant and provide a renewable energy system to meet Energy Policy Act requirements.

The team also developed a third option that proved more cost-effective. Because the building was cooling-dominant, any change that improved efficiency or extracted more heat from the ground loop reduced the ground heat exchanger size and cost. By incorporating airside energy recovery and geothermal domestic water heating; using a high-efficiency geothermal variable refrigerant flow (VRF) system, electronically commutated motor (ECM) pumps and light-emitting diodes; and adjusting the ground loop design, Hanson was able to improve efficiency and reduce cost. The size of the required ground heat exchanger was reduced by more than one third, and the cost premium for the geothermal conversion was cut to $77,000. Hanson’s life-cycle cost evaluation of this option revealed a simple payback of eight years. Through a comprehensive approach to evaluation and design, Hanson helped meet the client’s energy goals. The project also achieved LEED® Silver certification.

Hanson also conducted a geotechnical investigation and engineering services for site-specific seismic analysis of the existing facility to determine if seismic retrofitting was required. The services included seismic and Anti-Terrorism Force Protection (ATFP) upgrades to bring the building into compliance with current codes and Unified Facilities Criteria (UFC) requirements.

"Through Hanson’s integrated design process and their unique holistic approach, they were able to develop a different geothermal heat pump option that cost less than the conventional boiler/chiller VAV system would have and still be less than the originally proposed $1.2M conversion by the previous design. The estimated 51.2% energy cost savings of the HVAC conversion design allowed the project to achieve every available LEED energy credit, including one for innovation. The HVAC system design was a major contributor to the pursuit of LEED Silver for this project, which is a step higher than what was required by the government." — Matthew J. Boice, Deputy Base Engineer, Scott Airforce Base