ADVANCED INTERLAYER SOLUTIONS
Built in the mid 90s, the imposing 12-storey building – which houses a wide variety of offices, administration centers, chambers and courts – had to be brought up to current building codes following the devastating effects of Hurricane Andrew, one of only three category five hurricanes to hit the United States in the 20th Century.
The building already had a significant façade infrastructure as part of the original build, but after Hurricane Andrew in 1992 building codes in South Florida were significantly revised; demanding even greater protection from high speed winds and the effects of flying debris.
Architect Mark S. Beatty AIA, LEED A.P., who at the time worked for MPA architects, explains the reasoning behind the renovation: "The building was built just before Hurricane Andrew with insulating glazing in the façade. Following Andrew in 1992, Frances and Jannie in 2004 and Wilma in 2005, FEMA money became available and, coupled to a matching grant, the finances were in place to make it not only hurricane hardened but also to solve a water infiltration issue it was facing.
"We were extremely fortunate in that after some initial meetings spent poring over the original architect's drawings and running preliminary engineering calculations, we discovered that the existing façade frames had the potential to meet the revised codes – all we had to do was replace the glass panels," Beatty explains. "Based on the initial findings, we went forward and contracted with the Weitz company to reconstruct and test a modified mock up of the building's glazing and framing facade in a hurricane testing lab. It successfully passed the tests – including the county's high-velocity wind zone requirements – with only minor modifications to the beading. We then went forward and prepared a design based on new large-missile-impact glass panels comprising Viracon’s VP reflective coating on the surface of the insulating glass unit and 14.29 mm (9/16") laminated with 2.28 mm (90 mil) SentryGlas® interlayer on the inboard.
"The original glass façade panels were not designed to be impact resistant," he elaborates, "they were insulated doublepaned glass, so we needed a tougher replacement. As well as the impact performance however, we were also concerned that we were going to change environmental dynamics of the façade, which had originally been designed for a certain solar performance. The new system had to offer the same or better performance, or the building might not be able to cool itself. During the testing phase we ran a number of energy models to ensure that we could address the environmental issues. As it turns out, the new panels with the SentryGlas® interlayer actually offered better thermal performance after the application of a film coating that was as close to the original that we could find. The new coating, which, like the old coating, is reflective so you can't see inside the offices on outside walls, also contributed to the better thermal performance and retained the visual security for the occupants inside.