Case Study - ReVISION House Orlando 2011
Manufacturer: PGT Industries
Product: Wingard Impact Resistant Windows and Doors
Whether it’s preventing heat loss from a building, minimizing excessive solar heat gain and overheating, controlling condensation, maintaining occupant comfort, resisting strong winds and hurricanes, or preventing the building envelope from being breached by flying debris, it is the windows that are most vulnerable. Even with these downsides, we still need windows in buildings for daylight, views, and natural ventilation. So how do we balance the functional necessities with the performance shortcomings? With advanced glass and window technologies specifically intended to reduce risks and enhance performance. The ReVISION House™ team was faced with this same question and after reviewing available options selected PGT’s WinGuard windows and doors for the project.
From the pre-renovation starting point, the ReVISION House was a typical 1950’s ranch-style Orlando home: a poorly insulated concrete block, one-story slab-on-grade house, with single glazed aluminum-frame windows. As bad as the rest of the building enclosure was, the windows represented one of the weakest areas and conversely offered the highest potential for improvement. Viewed in the context of improving whole-house performance the design team analyzed the pre-retrofit conditions and the major window attributes needed to meet the ultimate performance goals. The criteria for improved window efficiency had to include solar-heat-gain-coefficient (SHGC); U-value; resistance to wind pressure; and resistance to wind-borne debris.
For energy performance and indoor comfort the two important components were SHGC and U-value. The existing windows were rated at 0.80 SHGC; and U-1.3, both at the bottom of performance curves for residential windows. The 0.80 SHGC means that only 20% of the non-visible solar-radiation is blocked by the glass allowing 80% of that energy to enter the home as long-wave radiation, otherwise known as heat. In a cooling dominated climate this was highly inefficient. The U-1.3 equates to less than R-1 meaning any thermal qualities were nearly non-existent.
The WinGuard windows chosen for the ReVISION House dramatically improved these values into the realm of high-performance. Using the insulated laminated Low-E SH700 glazing option the window performance values were improved to SHGC 0.34, and U-0.55. These improvements reduced the homes annual heating load by 5.3 MBTU’s, and cooling load 22.9 MBTU’s, or over 56% compared to the original windows. Improved comfort and reduced loads made it possible for a smaller HVAC system to be employed, resulting in cost savings, and further energy savings.
In hurricane country is it reassuring to know that products will perform during a big wind event. The WinGuard laminated windows are rated to meet Florida’s stringent wind-zone requirements for up to 150 mph. Wind-borne debris protection is also provided for up to 150 mph, without shutters or other separately attached protection. For hurricane protection this is critical, because if the windows fail and the enclosure becomes breached much more significant damage and even catastrophic failure may result.