Zurich Insurance Group’s new North American headquarters, a 784,000-square-foot, 11-story office building outside of Chicago, achieved U.S. Green Building Council LEED Platinum certification. Working closely with architects Goettsch Partners and developer Clayco, Thornton Tomasetti served as the sustainability consultant for the project, which is the largest LEED Platinum Core and Shell v2009 project in the U.S. and the only LEED Platinum CS v2009 project in Illinois.
Thornton Tomasetti played a key role in developing and analyzing project strategies to achieve LEED Platinum certification and a 62.7 percent whole building energy cost savings. The building includes multiple green roofs, energy efficient technologies, rainwater harvest and reuse, accommodations for electric and low-emitting vehicles, and native landscaping with more than 600 trees on 40 acres.
To verify performance and optimize the façade for reduced energy consumption, Thornton Tomasetti provided computational fluid dynamics modeling on the ventilated double-wall façade on the lower portion of the south-facing, three-story cafeteria. The 4.5-foot-wide double wall with integrated shades is designed to reduce solar gains in summer, while increasing the gains in the winter, as well as to improve daylighting, resulting in an estimated 33 percent energy savings in the adjacent space.
The building is composed of three primary “bars,” stacked and arranged to maximize views of the surrounding landscape and to optimize solar orientation. Thornton Tomasetti provided detailed daylighting studies using Honeybee software to evaluate the effects of automated interior blinds and fine-tuned the depth of the exterior shading devices for each orientation. The analysis optimized the depth of the shades for energy performance, which reduced peak solar gain for better thermal comfort and the size of the mechanical systems.
“We are delighted to have played a role in Zurich Insurance’s new LEED Platinum headquarters,” said Gunnar Hubbard, FAIA, LEED Fellow, principal and sustainability practice leader, Thornton Tomasetti. “Through our collaboration with the architects and developer, we were able to achieve a level of LEED certification that is unprecedented in Illinois and pairs seamlessly with Zurich’s commitment to sustainability.”
Joseph Dolinar, AIA, partner, Goettsch Partners, said, “Thornton Tomasetti’s expertise in high-performing building systems was instrumental in achieving our goal of LEED Platinum certification. The firm’s energy modeling of the building, targeted studies of façade shading concepts, daylighting studies, and double-skin wall analysis enabled us to optimize the façade design and greatly improve the overall building energy performance.”
Information provided by Thornton Tomasetti (www.thorntontomasetti.com/services/sustainability).