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Tuesday
Oct062015

The Tower at PNC Plaza – A Breath of Fresh Air

The Tower at PNC Plaza. Image © Gensler

On October 1, The Tower at PNC Plaza opened to the public, completing a five year design and construction process that started with a powerful and singular vision: create the world’s greenest skyrise. The Tower represents the culmination of a 10 year journey Gensler has taken with PNC, beginning with the first high-rise erected in Pittsburgh in decades (the mixed-use Three PNC Plaza) and followed by the first LEED Platinum office building in Washington, D.C., a net-zero bank branch building, and countless LEED-certified workplaces and bank branches across the country.

A tower of such ambition could not have happened without the teamwork and trust borne out of our long-term relationship with PNC, the collaboration of many consultants, engineers, and builders, and the relentless focus and detailed attention of a complete Gensler design team that included architects, interior designers, design strategists, and graphic designers.

It starts with setting a really high bar

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 greenest 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 façades and passive radiant systems emboldened our resolve to rethink how green office buildings could be designed back at home.

First and foremost, we realized we needed to define what greenest skyrise meant. 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 footprint similarly small, or more traditional buildings that were large but had a lot of bolt-on technologies to reduce carbon emissions. Neither fit our vision of what The Tower at PNC Plaza could or should be.

Instead, we 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), our 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.

To do this we put the user experience at the forefront of the design process. Our snapshot of the ideal workplace was that of an employee working on a park bench on a sunny afternoon, connected online via a tablet, enjoying the sunlight and abundance of fresh air. Most building designs seek to create optimized interior environments by solely focusing on importing as much daylight as possible. We wanted to go one step further by developing a passive natural ventilation strategy that would bring fresh air into the building, giving workers a true feeling of being outdoors and connected to nature.

So we set out to design a building that could breathe.

A purposeful and beautiful design

Our 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 façade, the characteristic that defines the building’s aesthetic and facilitates its high performance. To make a building façade 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. We wanted to reverse this 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 façade 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. We 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 façade further suggest the aerodynamic qualities of these wind-capturing devices.

The Tower’s vertical translucent glass panels. Image © Gensler

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 façade. This lets fresh air into each office floor. Desirable cool air comes in at the lower portion of the windows, and warmer air naturally exhausts through the top of the vents. The diagonal placement across the façade prevents the warm air from reentering the building on the next floor, thus assuring the building cools down naturally.

When open, the Tower’s panels bring cool air into the building and convey hot air outward. Image © Gensler

A similar level of thought went into the design of the inner façade 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 façade.

Employees can access the space between the Tower’s inner and outer façades and increase or decrease ventilation by opening or closing large sliding doors on the interior façade. Image © Gensler

For a building to inhale, it must effectively exhale. To complete the cycle, the double-skin façade 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 façade, gently pulling the passive flow of fresh air across the floorplate, into the building core and upward to the top of the building where it disperses.

The Tower’s façade delivers fresh air at low velocity through automatic dampers in the sill of the windows. Image © Gensler

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 façade. Not only does the wood provide the required thermal properties, the wood was sourced in Western Pennsylvania and gave the office interior a warmer ambience.

The Tower’s solar chimney pulls cooler air into the building’s core and disperses hot air. Image © Gensler

A building of and for Pittsburgh

The other striking quality of The Tower’s exterior façade is its sheer 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. We designed The Tower so casual passersby could look directly into the building and see the collaborative work taking place within.

The Tower's interior spaces are furnished with locally sourced materials, such as wood from Western Pennsylvania. Image © Gensler

The building’s interior was designed with collaboration top of mind. Two-story 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.

This five-story “park in the sky," is ventilated with fresh air and pulls elements of urban planning into the vertical plane. Image © Gensler

Just above the neighborhoods is a five-story 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.

Two Tower’s clear façade visually connects the building to the surrounding community. Image © Gensler

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 here in the U.S. and beyond.

The Tower at PNC Plaza. Image © Gensler

Hao Ko is grounded by the belief that the fundamental role of an architect is to elevate the human spirit, Hao strives to design beautiful places – ones that inspire people and impact the way they live, work and play. As the lead designer for the Tower at PNC Plaza, he is always pursuing a high level of conceptual thinking, pushing the performance boundaries, and detailed in final execution and craft. Contact him at hao_ko@gensler.com.
Ben Tranel is compelled by his belief that architects are stewards of the built environment, Ben relentlessly pursues the highest aspirations for each project. As the technical design director for the Tower at PNC Plaza with a specific focus on how to achieve the project aspiration, he takes pride in the artistry of building, where craftsmanship and a love of detail inform every aspect of the design concept and enhance the human enjoyment of the project. Contact him at benedict_tranel@gensler.com.

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