Firm name: M.E. Group
Project building name and location: Ambulatory Care Center at Lackland AFB, San Antonio, Texas
Type of building and type of project: Ambulance and Health Center, New Construction
Project completion date and project duration: 2011
Engineering challenges and solutions:
The multi-story Ambulatory Care Center (ACC) project at Lackland AFB in San Antonio, TX will replace all functions of Wilford Hall Medical Center. Using a phased design approach, this project provides for a new Primary Care Clinic, Diagnostic, Surgical and Therapeutic Treatment Center, Specialty Care Center with command and administrative functions, ancillary departments, education programs, and support spaces.
M.E. GROUP provided MEP design services for Phase 1, which includes the new construction of a parking garage, parking lots, a central utility plant and utility vault, and Building 1 of the development. These programs are distributed throughout three phases. Phases 2 and 3 will construct the remaining 3 buildings and demolish the old medical center. The project is targeting LEED Silver Certification.
M.E. GROUP’s design of Phase 1 is complete and this portion is currently under construction.
High Performance Features
- Water saving low-flow fixtures
- Occupancy sensors
- CO2 monitors provided for HVAC zones
- Condensate from cooling coils is captured and utilized for makeup water for the cooling towers
- Duplex instantaneous water-to-water plate
- Frame heat exchanger system
Engineering Challenge 1
The engineering portion of this multi-phase project was divided between two separate design A/E teams. HDR was to provide 25% design at which point M.E. GROUP and its design-build partners, would further the design through 100% Construction Documents. It was critical that the two design teams be integrated to allow for the successful completion of this project over the 6-month design schedule.
- Integrated design approach
- Precise and frequent communication between the two firms
- Regularly scheduled coordination meetings were imposed on all team members
- Rigorous design review process was established and then continued throughout the length of the project
Engineering Challenge 2
The energy efficient central equipment plant (CEP) design needed to be able to support the Ambulatory Care Center, (ACC) building 1, (128,000 SF), as well as the infrastructure and capacity for future planned buildings 2, 3, and 4 (combined total of 533,000 SF). The projects 25% design included a separate CEP structure located on the opposite end from building 1 of the ACC complex. A utility tunnel (or vault) was planned and routed from the CEP to ACC building 1. The project design-build team needed to coordinate the routing of piping, expansion loops, electrical, data, etc. below the structure of each building. Another project goal was to recover all of the condensate from chilled water coils in AHUs and Fan Coil Units. This would be used for cooling tower water makeup.
- All mechanical, electrical, plumbing, fire protection, and telecommunications infrastructure mains were routed in the vault and sized to service all four buildings
- The vault was routed to intersect the crawlspace below the future buildings 2 through 4 before making the connection to building 1 below the basement level
- The plant was designed to be tested, commissioned, and balanced using the load of building 1 alone so additional equipment, including a heat recovery chiller, cooling towers, pumps, boiler, etc. are planned to be provided in future phases of design and construction within the footprint of the constructed CEP
- Condensate from cooling coils was gravity routed into the vault and pumped back to a collection tank in the CEP therefore, the condensate recovery collection tank was sized for all four buildings (661,000 SF)
High Performance Design Solutions:
Solar Shading Device
Solar shading is the most effective passive energy saving strategy for the San Antonio climate, with savings potential during 28% of the year (2456 hours). The architect created this solar shading feature to reduce heat gain to the space, reducing load on the HVAC system and saving energy. This strategy contributed to the overall savings of 27.8% when compared to ASHRAE 90.1-2007.
BIM was used to coordinate MEP systems with architectural and structural systems. This allowed the design team to coordinate the routing of ductwork, hydronic piping, plumbing, electrical systems and other systems within structural constraints. This effort can greatly reduce the potential for coordination issues during construction.
High outdoor air requirements in healthcare projects consume a significant amount of energy, making demand controlled ventilation strategies very effective. Space mounted CO2 sensors are provided in all densely occupied spaces to monitor and reduce ventilation airflows below design based on demand. Occupancy sensors and time of day schedules are also in place to reset ventilation airflows based on zone-by-zone occupancy. Air handling units are also equipped with outdoor airflow measuring stations. These sensory inputs dynamically reset airflows at the air handlers based on demand.