Window retrofit technology can cut energy use by 25%

A 40-year-old Philadelphia high-rise was fitted with insulated glass units to study energy-use reduction and improved indoor comfort.

Turns out that 400 Market Street, a 12-story building in Philadelphia, used the RENOVATE by Berkowitz window retrofit system to reduce its annual heating and cooling energy consumption by more than 25 percent and significantly improve indoor comfort. The Department of Energy funded the year-long study of the building built in 1972.

The 200,000-square-foot building was retrofitted with the Renovate system’s Platinum version in 2011, which added a factory-made insulating glass unit (IGU) to the original single-pane windows, creating an energy-efficient triple-pane IGU. As part of a $1.6M DOE-funded study conducted by the Home Innovation Research Labs and Quanta Technologies, Inc., the building demonstrated the ability of low-e retrofit glazing systems to improve the energy efficiency of older commercial buildings.

“At more than 25 percent, the whole building’s heating and cooling energy savings were significant and on par with what I expected, but frankly, I was surprised by how much the savings were in the perimeter offices—up to 35-60 percent, depending on orientation," said project manager Thomas Culp of Birch Point Consulting, LLC. "It shows the potential the Renovate system has for significantly improving an existing commercial building with more glass surface area."

According to Culp, the study also examined four unoccupied perimeter offices in the building, two facing east and two facing north. One office in each pair was retrofitted with the Renovate system, while the other was left untouched. “The data showed that the surface temperatures of the retrofitted windows were typically 20 degrees warmer on winter days and 10-20 degrees cooler on summer days, substantially improving comfort and usability of the space,” he said.

“People tend to focus on the energy efficiency of new buildings, but there is a huge opportunity to improve a large number of older buildings that have single-pane windows,” Culp said.

“Retrofitting these buildings with the Renovate system can provide comparable energy savings at up to half of the cost of a traditional rip-out-and-replace project,” added Darrell Cherry, business development manager for Renovate by Berkowitz.

Read more about energy-efficient windows and doors.

Topics: Remodeling, Windows

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