St. Louis Power House

Re-energizing a historic landmark

CannonDesign St. Louis Office

St. Louis, Missouri, United States
32,000 square feet
LEED Gold Certified

Constructed in 1928 and designated as a landmark by the National Historic Register, the Power House once provided coal-fired steam heat to a dozen buildings in downtown St. Louis. Decommissioned in 1980, the building became a shell of its former self—a large vertical building with a relatively small footprint, completely empty.

In 2007, we purchased the building and began the meticulous process of preserving the structure while transforming it into the new home for our St. Louis office. The Power House spoke to our team because it matters deeply to the city of St. Louis and we knew it could matter again in entirely different ways. We were inspired by the building, and we sought to create a design solution that would inspire others.

Our transformation of the building went on to win an Honor Award from the American Institute of Architects—the highest honor bestowed upon building projects.

Powerhouse Before
Once a power house providing coal-fired steam, the building sat vacant for nearly three decades before becoming our St. Louis office.
Power House After
The building’s “revival style” exterior, featuring tall, arched windows on three street facades and fine terra cotta detailing, has been fully restored.
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The building’s “revival style” exterior, featuring tall, arched windows on three street facades and fine terra cotta detailing, has been fully restored.


  • An interesting dialogue between present and past. The project maintains, preserves and reestablishes the integrity of the existing, historic building while creating modern, attractive and energy-efficient interior spaces that accommodate user needs. A balanced and pleasing chiaroscuro effect is produced between new materials reflecting light and the existing materiality of the project that absorbs light.

    Institute Honor Award Jury American Institute of Architects
Powerhouse Before 2
Remediating the site was a monumental task, removing toxic materials and lead paint, as well as contaminants that were found in the soil.
Power House
To make the most of the voluminous space, we designed a structure within the existing structure to provide the necessary square footage needed.

Although the building’s exterior shell and original structural steel were fundamentally sound, transforming the space into a workplace required a creative spatial solution that exploited the building’s massive volume in spite of its relatively small footprint.

Our solution involved designing two separate floor plates above the ground floor inside the tall volume, thereby creating two extra floors and ample collaborative meeting space and workspaces for approximately 120 employees. In addition, an elevator shaft, kitchenettes on each floor, and two staircases located against the back wall in the northwest and southwest corners were all achieved within the historical building envelope.

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  • This project demonstrates the notion that the most sustainable building is the one not built. If sustainability emphasizes "leave no footsteps," this one seems to dance.

    Contract Magazine Interiors Awards Jury
Power House
The new floors are set back from the building’s spectacular windows to maintain the building’s sense of transparency and volume.
St. Louis Office
The openness on the ground floor is the ideal setting for community and office events.

Within the original framework of the building, a model shop and materials library plus a boardroom are carved out of the basement. On the roof, an oblong structure originally used to store coal conveyor equipment now houses a conference room and staff lunchroom.

Power House
Power House
Model shop

The LEED Gold building now performs at an exceptionally high level, exceeding even forecasted energy-use predictions.

Power House
The interior was completely rehabilitated, with installation of high-performing HVAC, plumbing and electrical infrastructure. All the windows were replaced with historically accurate replacements.
Power House
The workplace was designed to house 120 teammates with room to expand.