(Above) Front side and rear side of building. Photo credit: Chad Baumer Photography

By Joshua Bowditch

Achieving Sustainable Design with GateLite Panel System at Baptist Hospital (Pensacola)

Through a design-assist collaboration with architecture firm Gresham Smith, GATE Precast has artfully demonstrated the use of innovative building products on a large scale with its prefabricated GateLite unitized façade system featured at the Baptist Hospital campus in Pensacola. Here the concept of prefabrication is taken a step further by integrating expansive curtain wall window segments into the panels at the precast facility, which expedited the construction schedule by approximately three months. With GateLite panels, concrete and steel are used synergistically. This design innovation allows for architectural precast concrete cladding at an unusual thinness of only 2-1/4” thick. The GateLite panels use 60% less concrete than regular precast concrete and 50% less steel than conventional light gauge steel framing1. This is an example of the concept of dematerialization, the use of less material to fulfill an intended purpose, which corresponds to less embodied resources, and lighter weight load. The panels have the advantages of precast concrete but in significantly lower quantity of materials. From a construction standpoint, the advantages of the GateLite unitized system are simplification of the exterior wall assembly, consolidation of the construction process, and improved quality, safety, and predictability.

Unconventional Components

As precast concrete typically contains steel as rebar, concrete must provide sufficient cover over the steel reinforcement2. Instead of relying on rebar, GateLite panels are innovatively supported at the interior side by a steel tube mainframe, thereby allowing the thickness of the overall concrete to be reduced. Pins of 1/4” diameter steel anchored or embedded in the precast transfer the loads to the mainframe of mild steel tube. Despite the thinness, impermeability to the exterior is provided by well-consolidated precast concrete with low water/cement (w/c) ratio3. The steel tube mainframe is prefabricated with hardware connections for efficient installation to the building structure and functions as a drywall-ready substrate, eliminating the need for furring along the walls. GateLite panels have a 2” layer of HFO (hydrofluoroolefin) polyurethane spray foam insulation, with zero ozone depletion, an ultra low GWP (A1-A3, is 3.47 Kg CO2e)4 and R-value of 7.5 per inch1, applied at the precast facility. The foam is produced by combining two separate formulations that react and expand when combined through the application process; after the foam has cured it is chemically inert4. As a closed-cell foam, the HFO provides an air and vapor barrier at the interior side, in addition to highly efficient insulating value4.

Design Considerations

Efficiency of the system is furthered by repetition in the design. Repeating window and aesthetic patterns not only give orderliness but also can enhance aesthetic appeal. Through a high level of coordination between GATE and the design team, the GateLite componentized modular system lets the architect have tremendous creativity in designing the building envelope. Precast concrete was selected for the new Baptist campus to emulate the varying shades of earth tone colors of the original brick hospital, which had outlived its useful life. The panels are complemented by cool tone reflective glass, while joint lines and integral grooves delineate rhythmic patterns. Precast concrete is inherently colored with integral pigments, and has an ingrained finish, thereby eliminating the need for repainting or refinishing. Precast concrete has outstanding longevity and minimal long-term maintenance, which allows the Baptist Hospital to serve as a safe haven for its community for 75 to 100 years. Sustainability in the building industry often involves trade-off because of complexity and multiplicity of applicable factors, but GateLite is an outstanding option for achieving sustainable design.

Hauling of panels and installment of panels. Photo credit: GATE Precast Company

Sealed Airtightness

Because glass is contained in aluminum frames, window openings involve two joints, one at the glass-to-frame interface and another at the frame-to-perimeter (adjacent surface) interface. At Baptist Hospital Pensacola the windows are YKK AP “YHW 60 TU”. These are preglazed, meaning the glass is structurally and hermetically sealed (unitized) to its aluminum framing at a fabrication shop, so that the sealant is applied and cured in a controlled environment, where there is no variation of temperature and humidity, and no exposure to airborne contaminants5. In comparison to shipping directly to the Pensacola jobsite, the window assemblies were shipped to GATE-Monroeville, AL, which saved 1,032 transportation miles. Installation, caulking, and inspection of the integral windows in the GateLite panels are performed on the ground and in a controlled environment, away from the rigors and variable conditions of the jobsite, improving safety and reducing jobsite waste. Joints between respective GateLite panels are sealed by inserting backer-rod of closed-cell material and using low-modulus silicone sealant. Silicone sealants are chemically stable and extremely durable with excellent resistance to weathering and aging6.

Architectural Stewardship

Aesthetically interesting as Baptist Hospital campus may be, these aspects would be generally unknown. It is publications like this one that can provide representation of these sustainability aspects through description and illustration. That would be the intent of “Architectural Stewardship”.

Disclaimer

This article of Architectural Stewardship was sponsored by GATE Precast Company.

 

References
1GateLite by Gate Precast. 2021. Health Product Declaration Collaborative.
2Architectural Precast Concrete Manual, Third Edition. 2007. Precast/Prestressed Concrete Institute. Page 456.
3Architectural Precast Concrete Manual, Third Edition. 2007. Precast/Prestressed Concrete Institute. Page 307
4ASTM International. 2022. Environmental Product Declaration: Spray Polyurethane Foam Insulation (HFO). Spray Polyurethane Foam Alliance.
5Takish, M. S., M. H. Haugsby, C. M. Schmidt, and W. J. Schoenherr. 1989. Structural Silicone Sealant Curtain Walls: Field or Factory Glazing? In: Science and Technology of Glazing Systems, ASTM STP 1054, American Society for Testing and Materials, pp. 58-65. C. J. Parise (ed.).
6Beall, C. 1999. Thermal and Moisture Protection Manual. McGraw-Hill. Page 74-81.

About the Author: Josh Bowditch

As a native resident with architectural experience and environmental regard, Josh Bowditch is intent on publishing about sustainability in the architectural and building construction industry locally. From being in the architectural profession, Josh has an understanding of the processes involved. Is it possible to reconcile environmental considerations with development? The word sustainability has various connotations but indeed can be viewed in the context of stewardship. Read Previous Article.