The Tower at PNC Plaza / Gensler / USA

The Tower at PNC Plaza 

• Architects: Gensler
• Location:  Pittsburgh, United States
• Client:  PNC Financial Services Group
• Structural Engineer:  Buro Happold
• Structural Material:  Composite (Core: Reinforced Concrete; Columns: Steel; Floor Spanning: Steel)
• Project Years:  2010-2015
• Tower Gross Floor Area:  56,485 m2 / 607,999 ft2  
• Building Height:  166 m / 544 ft / 33 storey
• Development GFA:  74,322 m2 / 799,995 ft2  
• MEP Engineer:  Buro Happold
• Main Contractor:  P J Dick Inc.
• Acoustics Consultant:  Threshold Acoustics LLC
• Energy Concept Consultant:  Buro Happold
• Facade Consultant:  Heintges & Associates; Permasteelisa Group
• Geotechnical Consultant:  Langan Engineering
• Landscape Consultant:  LaQuatra Bonci Associates
• Lighting Consultant:  ESI Design; Fisher Marantz Stone; The studio company
• Sustainability Consultant:  Buro Happold; Paladino and Company
• Vertical Transportation:  Edgett Williams Consulting Group Inc.
• Wind Consultant:  Alan G. Davenport Wind Engineering Group

LEED Platinum Energy Label

When Gary Saulson, PNC's Director of Corporate Real Estate, came to Gensler's Chicago office in 2011 for The Tower at PNC Plaza project kick-off, he challenged the team with an audacious goal: "design the greatest skyrise in the world." Months earlier, the design team had traveled to Europe and Canada to study best-in-class high-performance buildings. Seeing first-hand the focus on the quality of the built environment with respect to performance, and the ubiquity of building technologies such as double-skin facades and passive radiant systems emboldened our resolve to rethink office buildings could be designed back at home.

At the time, the term "green" was almost uniquely focused on LEED standards and energy conservation. This meant that buildings fell into two categories: buildings that were very small and kept their energy footprints similarly small, or more traditional buildings that were large but had a lot of bolt-on technologies to reduce carbon emissions. Neither fit their vision of what The Tower at PNC Plaza could or should be.

Instead, they crafted a vision for the project that holistically addressed user experience, health and wellness, energy savings, workplace, innovation, and responsible community stewardship. Inspired by the newly introduced Tesla car, which had redefined its industry by uniting driver experience and environmentally friendly performance (one could go from zero to sixty in under four seconds and have a zero carbon footprint in a car that also looked great), Gensler's team sought to design something that would exemplify the best of contemporary architecture, facilitate a transformational employee experience, and set new benchmarks for saving energy and water.

So they set to design a building that could breathe -

Their guiding ethos throughout the design process was what we call the Three Pillars: workplace innovation, energy response, and community building. Design elements needed to purposefully support one or more of these pillars or else they were discarded for better ideas.

This guiding ethos explains The Tower's facade, the characteristic that defines the building's aesthetic and facilitates its high performance. To make a building facade that could function as a breathable skin and facilitate natural ventilation in a passive manner, the team employed a double-skin design. Opening a window in a high-rise building is not challenging in and of itself - an occupant in the newly opened Empire State Building in 1931 could open a window. But the physics of tall buildings has long meant that opening a window causes air flow out of the building rather than into it. They wanted to reverse the paradigm and allow air to move inward whenever people chose to open their windows. This would give occupants the cooling sensation of air moving across their body; it would feel as if the building itself was inhaling.

How does The Tower achieve this? 

Through innovative facade design that carries a distinct aesthetic touch as well as unique functionality. The characteristic that one first notices upon looking at The Tower's exterior are the slim, vertical translucent glass panels that stagger in a diagonal pattern. They designed these panels to resemble boat sails and spaced them to follow the cadence of the warp and weft in the weave of such sails. The flowing curves in the facade further suggest the aerodynamic qualities of these wind-capturing devices.

This pattern is not simply a poetic one. On days where the weather conditions are ideal, the building's management system instructs the operable panels to open outward, parallel to the facade. This lets fresh air into each office floor. Desirable cool air comes in at the tower portion of the windows, and warmer air naturally exhausts through the top of the vents. The diagonal placement across the facade prevents the warm air from reentering the building on the next floor, thus assuring the building cools down naturally.

A similar level of thought went into the design of the inner facade of the double-skin. While fresh air is delivered at low velocity through automatic vents in the sill of the windows, the design team also wanted to make sure there was an appropriate level of manual operability that would give users control over their personal environments and allow them to engage directly with the performance of the building. Large sliding doors were thus designed to allow an employee to augment the ventilation of their space and to experience the exterior, porch like cavity of the double-skin facade.

For a building to inhale, it must effectively exhale. To complete the cycle, the double-skin facade works in tandem with a solar chimney located throughout and at the top of the building. Instead of turning sunlight into energy with photovoltaics (an inherently inefficient process), the building's roof harnesses the sun's abundant rays and captures them as heat. This heat inside the solar chimney acts as a magnet for the cooler air entering through the exterior facade, gently pulling the passive flow of fresh air across the floor-plate, into the building core and upward to the top of the building where it disperses.

The materiality of the envelope was also thoroughly considered for performance and impact on the environment. To minimize the embodied energy in the building, wood is featured in a unique way as the primary material of the inner facade. Not only does the wood provide the required thermal properties, the wood was sourced in Western Pennsylvania and gave the office interior a warmer ambiance.

The other striking quality of the Tower's exterior facade is its shear transparency. PNC did not want a fortress-like new home; they wanted the building to be visually connected to the community of Pittsburgh from the lobby to the very top floor. They designed The Tower so casual passersby could look directly into the building and see the collaborative work taking place within. 

The building's interior was designed with collaboration top of mind. Two-storey neighborhoods connect groups of office floors in a single space offering an array of alternative work environments, pantries, office services, and a variety of shared conference rooms. These neighborhoods, stacked vertically on the building's west side are clearly visible from Market Square. Each have their own subtle variation in furnishings, encouraging people to move from neighborhood to neighborhood. This vertical stack of neighborhoods is stitched together visually by a colorful mural that runs the height of The Tower and is inspired by PNC's history.

Just above the neighborhoods is a five-storey indoor "park in the sky." It is a low-energy and seasonal space that brings a bit of the outdoors inside. It provides an incredible panoramic view of the city and is a window into the organization from the outside.

The base of the building features highly contextualized amenities. The food service is purposefully undersized to encourage people to support the surrounding restaurants in downtown, The lobby celebrates the legacy of Pittsburgh by using materials both familiar and local and provides an artful beacon that communicates the story of the building to all.

The Tower at PNC Plaza redefines the urban high-rise headquarters typology and raises the bar for how forward-thinking companies can use architecture as a means to inspire and enable great work to happen within their organizations. With a focus on how intuitive, high-performance technologies integrate into a building and enhance employee experiences, and a dedication to augmenting the city it lives in, The Tower at PNC Plaza sets a new benchmark for sustainable building design in the United States and beyond.