July 30, 2020
Inspired by classical pavilion architecture, using Doric Order and monumental half-round column design, Capitol Towers in Charlotte, North Carolina, is an iconic office building combining old-world Roman influence with high-performance glazing and modern energy efficiency. The ornate façade, designed by LS3P in Charlotte, showcases concrete pillars and a prominent exterior glazed with neutral-reflective, low‑emissivity (low-e) glass, which helped it achieve the Leadership in Energy and Environmental Design (LEED) Gold certification.
The buildings design also prescribed preferential parking for low-e vehicles, smart HVAC and air filtering systems, and solar control low-e glazing.
The proprietary low-e glass was chosen because its bronze coloration complemented the overall building color palette and its performance was vital to helping attain LEED Gold certification, said Jim Williams, vice-president of LS3P. “Even with the classical design, we achieved a 60/40 glass-to-solid-wall for the overall façade.”
A mixed-use structure, Capitol Towers includes 43,664 m2 (470,000 sf) of office space, a seven-level, 1700-capacity parking garage, and 2787 m2 (30,000 sf) of retail space. To minimize local impact and attract progressive businesses, energy efficiency and sustainability were major design considerations.
A Monroe (North Carolina)-based glass manufacturer installed floor-to-ceiling windows fabricated with low-e glass throughout the buildings, except for the street-level windows where local building code dictates the use of clear glass. The low-e glass advances the project’s energy-efficiency ambitions by uniting solar heat gain coefficient (SHGC) of 0.23 with visible light transmittance (VLT) of 42 percent.
The structures were also designed for visibility. A coffered dome, functioning as a mechanical screen, top the buildings off at a height of 61 m (200 ft). With an exterior reflectance of 32 percent, low-e on bronze glass delivers a natural aesthetic that harmonizes with the concrete exterior while affording views of Charlotte’s Carnegie District of SouthPark.
“The high-performance, energy-efficient windows at Capitol Towers allow for an abundance of natural light to fill the space without the radiant heat gain from the sun,” said Patrick Stark, director of energy and sustainability for property manager Lincoln Harris. “The windows allow tenants to keep their blinds open and connect with the outdoors without sacrificing comfort or energy efficiency.”
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