Dynamic or Static?
- Feb 09, 2012
Exterior sun-shading devices, long popular in Europe, are just starting to attract a following in the United States. They carry a number of benefits, although their long-term payback period remains a deterrent to adoption.
Those pursuing them, among them sustainability leader Hines, may choose from a couple of different options. One is the fixed shading devices that appear poised for increasing popularity among the next generation of U.S. high-rises; the other a modern motorized, or “dynamic,” alternative.
A meaningful benefit of motorized systems is that they adjust movable parts to maximize daylighting on cloudy days—or pretty much any time the sun isn’t shining directly onto the corresponding façade.
But while retractable operable shading elements such as louvers and rollers tend to be quite effective minimizing heat gain in low-rise buildings, their applicability is limited for now because high winds become a daunting challenge above five stories or so, related Mark Perepelitza, associate partner with Zimmer Gunsul Frasca Architects.
More new low-rise commercial developments will likely see combinations of fixed and dynamic systems—as is the case at First Western Development’s four-story The Terry Thomas in central Seattle’s South Lake Union district. The property’s automated louvers and blinds and fixed shading devices are coordinated with operable windows and various other design and operational strategies allowing for passive cooling via natural ventilation.
Accordingly, the Weber Thompson-designed project doesn’t need a mechanical cooling component whatsoever, a fact that also provides space for higher ceilings that help with ventilation as well as tenant marketing. Likewise, its fixed glass shades are strategically tinted, installed and angled outside certain windows to help retain views while minimizing heat gain and glare.
For his part, Jerry Lea, Hines’ vice president of conceptual construction, expects U.S. developers to opt for more motorized models going forward as subcontractors here become accustomed to installing sophisticated systems that have become popular in Europe.
And Rob Kistler, founding principal of The Façade Group, suggested the shading-system discipline generally is bound to see even more innovation in coming years as it adapts to quite an array of high-tech energy-efficient and even energy-generating glazing systems that are about to take hold in commercial buildings.
Shading device developers in fact already have all manner of as-yet-unrevealed cool and futuristic systems in the works based on client input, he added—but purposefully avoid showing their hands to competitors before initial installations.