The renovation of the Grant-Deneau tower includes around 2,400 VIG panels, in both vision and spandrel areas, totaling 60,000 square feet.

The Grant-Deneau tower in Dayton, Ohio, was vacant for seven years when Columbus, Ohio-based developer Windsor Companies purchased the glass gem in 2019.

Built in 1969, the 22-story, mid-century tower was Dayton, Ohio’s, first modern skyscraper, and was listed on the National Register of Historic Places in 2016.

Built in 1969, the 22-story, mid-century tower was the city’s first modern skyscraper, and was listed on the National Register of Historic Places in 2016. The tower, however, was flawed. So flawed, that no one wanted to work there. The problem wasn’t mold, asbestos or bugs. It was the glass. The monolithic glazed building’s heating and cooling costs were so high, that no one could afford to work there. So, they left.

Now owned by Windsor, the firm had its eyes set on renovation. As the process began, Alex Manno, director of construction for Windsor, was sure there had to be an energy-efficient glass they could use. But not just any high-performance glass would work. As a historic site, the tower had to maintain its original aesthetic.

“I was searching for ‘super-efficient’ glass online and vacuum insulating glass (VIG) popped up,” he says.

Through that search, he found Vacuum Glass LLC and began the conversation with its president and chief technical officer Dave Cooper. Those conversations led to what is currently the largest VIG retrofit in North America.

The project includes around 2,400 VIG panels, in both vision and spandrel areas, totaling 60,000 square feet. Vacuum Glass provided fully tempered 10-mm VIG panels to replace the original curtainwall’s annealed glass.

Minimal structural changes were needed, helping to reduce costs and enhance energy efficiency. The renovation includes the use of the original gasket from Stanlock, as well as the same profiles.

Manno says there are about 18 different sizes, including arched windows on the 22nd floor, which will become penthouse units.

Cooper says it took about three months to fabricate the units, and all of the glass is currently on site.

Because the tower is a historic site, it was also eligible for tax credits on both the federal and state level.

The project has received acknowledgment from the State of Ohio for a historical tax credit in the millions by matching the new tempered VIG to the original annealed monolithic glass. Project developers are also working toward the 179 D tax credit for energy efficiency upgrades.

Renovation work began in January 2022. Once complete, the tower will include a mix of commercial space on the lower floors and residential units on the higher levels. Developers are targeting July 1 for completion.

“This is the largest VIG glazing project in North America at this time,” says Cooper. “The ability to take an abandoned 22 story tower in the center of a city and upgrade it for mixed use occupancy makes this project a significant milestone for VIG, let alone the city of Dayton. Coupling VIG with a heat pump solution and tax incentives will drastically lower both capital and operating costs. Such a significant thermal insulation to the envelope glazing is just not possible with standard insulating glass.”

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