New HVAC Design to Give Historic Army Band Hall a More Sustainable Life
As part of major renovations to historical Building 615 at Joint Base San Antonio/Fort Sam Houston, home to the U.S. Army Band known as “Fort Sam Houston’s Own,” our Facilities team designed an innovative new heating/cooling system that saves energy and will give the facility a more sustainable life over the long term. Design was completed in 2019, and the renovations are underway.
The Military Engineer, the magazine of the Society of American Military Engineers, features the project in its March/April issue. The article, A Major Tune-Up: Energy-Savings Makeover for Historic Army Band Hall was written by Mechanical Engineers Ryan Edwards and Ai Sexton and Vimal Nair, Assistant Division Manager for Facilities.
Project Background
The U.S. Army Bands make music all over the world, and the 323rd Army Band known as “Fort Sam’s Own” prepares for its performances in history-filled Building 615 at Joint Base San Antonio/Fort Sam Houston.
Built as a barracks in 1891, Building 615 has at times housed a dining hall, gym, surgery training center and classrooms. It was converted into a band hall in 2008 but within a decade required upgrades to meet current needs and building codes.
Replacing the outdated ventilation system was a priority as part of a larger renovation. Besides being inefficient, the system was overcome by mold in many places, creating an unsafe environment. Other challenges in updating the ventilation system included:
- The building’s historical nature meant no roof vents or exterior wall penetrations could be added for bringing in fresh air.
- Tight ceiling spaces not originally designed for air conditioning could not be expanded.
- Military restrictions on air systems limited design options.
Working as part of the Kenall-Freese and Nichols Joint Venture, our Facilities team devised an energy-saving, more efficient system to give the facility a more sustainable life over the long term. This innovative approach focused on handling the envelope and ventilation loads separately while preconditioning outside air with energy recovery wheels and controlling indoor temperatures with dual-technology occupancy sensors.
Challenges
Building 615 measures 26,800 GSF over two stories. It was not designed for air conditioning 130 years ago, despite San Antonio’s humid, blazing-hot summers. This newest ventilation system makeover needed to serve upgrades to offices and practices rooms and addition of a performance hall.
The project overall aims to respect as many of the building’s historical elements as possible. For the ventilation component, that meant using techniques such as:
- Adapting antique attic vents to avoid new openings in the slate roof
- Minimizing the number of exterior wall penetrations for outside air
- Reclaiming antique window openings that were used for outside air on previous renovations
- Limiting equipment near the distinctive building exterior
- Preserving unique elements such as a stained-glass inlay (formerly a window) over a duct intake
Other special considerations included mitigating sound entering/exiting practice rooms and carefully controlling the humidity level for instrument storage.
Key Solutions
The building consists of an east wing and a west wing and originally was heated/cooled using a two-pipe, manual switchover system served by an air-cooled chiller and a gas-fired boiler, with zero energy recovery. The design replaces the entire system with a four-pipe system, including new fan coil units (FCUs) and dedicated outside air systems (DOAS) with energy recovery.
The facility consumes a considerable level of energy because of the outside air required to properly ventilate the space and because of the location’s high humidity. To address this, energy recovery using preconditioning with enthalpy wheels was incorporated into the new system to make the HVAC system sustainable. It’s designed with a compact configuration, which also provides a solution to the building’s space limitations.
The energy recovery approach reduced the size of the chiller required from 100-ton to 72-ton and achieves 30% cooling energy savings and 5% heating energy savings. The new system also controls humidity better and no longer requires a manual changeover.
Another issue was cooling the new 3,100-square-foot performance hall efficiently. The space has a 200-person capacity but will be used by only a few people much of the time. Military facilities regulations limited the options for a new cooling system, and the team wanted to avoid a system that would waste energy overcooling the hall while it’s largely unoccupied.
The solution was to divide the space into three zones, each monitored by a dual-technology occupancy sensor to detect movement and thermal projection within that zone. The system modulates the amount of outside air brought in based on occupancy levels the sensors detect, creating a healthy environment when the room is fully occupied and saving energy when few people are in it.