The smart, renewed Willis Tower welcomes the outside in

Buoyant enthusiasm filled the air during the ribbon-cutting for the renovated Willis Tower in May 2022. Taking the stage in an expansive, travertine-glazed lobby, David Moore, senior vice president of EQ Office, a realty management company of Blackstone, behind the $500 million project, invoked the celebrated history of the 110-story steel and glass tower, “a symbol of Chicago’s ingenuity, technical skills, and shared grit.”

Moore then pivoted to the need to upgrade the nearly 50-year-old late-modernist icon for a new era. “We began to reimagine Willis Tower as more than just an office building—as a place that connected people that will become a thriving energetic hub of the neighborhood and the city.”

A fortress of solitude comes down

In 1974, the possibility that the project, called the Sears Tower until 2009, “could challenge the planned height of the World Trade Center in New York, then under construction, was extremely appealing to a Chicago business, its architects, and the city,” according to Skidmore, Owings & Merrill, the experiment since 1936 (Electa, 2006). The SOM team responsible for the building’s design—led by architect Bruce Graham and structural engineer Fazlur Khan — were inspired by a handful of cigarettes, said Francisco López de Arenosa, the firm’s communications manager. After cupping and stacking cigarettes in his palm, Graham sketched a grid of packed steel tubes of graduated heights that would come to define Chicago’s skyline.

Yet despite its grandeur from afar, the building, like many in its era, was unwelcoming at the street level. In a bid to retain anchor tenants, like United Airlines and Morgan Stanley, attract new businesses, and revive visitor interest, EQ office hired the global architecture firm Gensler, Seattle-based SkB Architects, and Philadelphia-based landscape and urban designer Olin to redesign the tower’s podium, lobby, and upper level offices. Prior to the renovation, the building offered tenant access only from a flight of stairs off Wacker Drive to its west; visitors to the glass viewing platforms at the Skydeck Chicago observation tower, redesigned by SOM and engineering firm Halcrow Yolles in 2002, had to enter separately along West Jackson Boulevard.

“Gensler had a challenge,” says Gary Michon, general manager of Willis Tower. “When Sears built this, they built it as a fortress, with those big granite walls that surrounded the building. It wasn't warm and inviting. We wanted to open up the building to bring people in, but still provide the security that tenants are asking of us.”

The first part of that challenge was largely spatial and programmatic, says Gensler principal Benjy Ward. In addition to reglazing the building’s 463,000-square-foot base with glass and white terra cotta tiles, the renovation added public entrances on West Jackson and Franklin Street, updated the ground floor tenant entrance on Wacker Drive with black steel columns and a skylit vestibule, and enlivened the interior with two new lounges, public seating areas, the Color Factory art museum, a food hall called Catalog (an homage to Sears & Roebuck Co.’s mail-order business), and a fourth-floor roof garden with native grasses, oaks, and a resident bee colony. The lower levels now have the feel of a boutique hotel, with casual seating areas and quiet alcoves where workers can plug in their laptops or meet with clients outside the confines of the office. Ward puts it best: “It’s a great post-pandemic building that was strangely designed before the pandemic.”

Improving internal systems

Optimizing building performance and updating aging mechanical systems were other measures to enhance the tower’s property value, Michon says. EQ Office consulted with the New York–based data and analytics firm Aquicore on the energy and water use overhaul, which targeted everything from the air handling units and lighting system to the cooling towers and chiller plants. In the Willis Tower’s restrooms, more than 300 Kohler toilets and Sloan flush valves replaced existing units to reduce water usage from 3.5 to 1.6 gallons per flush. More than 200 Sloan urinals have reduced flow from 1 gallon per flush to 1 pint per flush. In addition, 750 aerators installed in sink faucets reduce the flow rate from 2 to 0.5 gallons per minute.

The team specified that the air handling units enforce demand setpoints, automatically reset at programmable start and stop times, and stagger equipment startup to avoid energy peaks. Three rebuilt chillers, which circulate 8,000 tons of cooled water, increase the units’ electrical efficiency from just under 0.9 to 0.6 watts per ton—a roughly 30% increase.

Johnson Controls’ Metasys Building Automation System replaced the outdated system; more than 60,000 control points, including water use from toilets and faucets, the temperature setpoints of the heating and cooling systems, and the electrical output of 300 LED strip fixtures, 600 tube lights, and 100-plus motion sensors, are managed. Together, Michion says, these renovations have helped make Willis Tower “the largest LEED platinum building in the U.S.”

Arguably, the most noticeable system change is an ongoing $75 million modernization of the building’s original 94 elevators and 108 passenger cabs, which make an estimated 46,000 trips daily. Artificial intelligence–powered smart dispatch technology by Otis routes passengers going to the same or nearby destinations to reduce passenger wait and journey times, reducing electricity consumption by 35% while reducing travel times during peak hours by 30%. Along with a braking system that feeds electrical energy back into the building’s power grid as elevators descend, the routing system is expected to significantly reduce peak-hour travel time when complete in September 2024.

Attendance numbers

Behind the turnstile lanes, closer to the tenant elevators, screening stations resemble those at a Transportation Security Administration–managed airport check-in. Disguised by paneling and monitored by security personnel, who may perform additional checks on registered guests, they are largely invisible to the public “so it looks like a friendly environment,” Michon explains. “When you're coming in, it's very casual, but to get past our security, you have to go through the screening stations.”

The spatial configuration of the floor plan reinforces security protocols. Cascading elevation changes imply distinctions between public and more controlled tenant zones. For instance, an elevator bank to the fourth-floor landscaped terrace can be publicly accessed without digital credentials from a concourse at the northern edge of Catalog. On the other hand, access to elevators leading to Skydeck Chicago is overseen by security personnel and tightly restricted. At the entrance, two floors beneath ground level, visitors must pass through an alert system of infrared body scanners by the Chicago-based cybersecurity service company Evolve Security.

Andy Farmer, vice president for corporate identity at Idemia, says the biometric credentialing system, which regulates access to higher level building floors and expedites entry, is compliant with the Illinois Biometric Information Privacy Act, one of the most stringent state laws protecting individuals’ privacy data. The Illinois law, elements of which have been adopted in California, Texas, New York and Washington, requires participants to sign a consent form and regulates how data will be captured, stored, and deleted.

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