Window Retrofit Reduced Building’s Energy Consumption by More than 50 Percent

The RENOVATE by Berkowitz LLC (RbB) window retrofitting system has enabled 400 Market Street, a 12-story building in Philadelphia, to reduce energy consumption in perimeter offices by over 50 percent, according to results from a year-long energy study.

Built in 1972, the 200,000-square-foot building was retrofitted with the RbB system in late 2011, converting its original single-pane windows into triple-pane insulating glass units (IGUs). As part of a $1.6 million U.S. Department of Energy- (DOE)-funded study conducted by the NAHB Research Center and Quanta Technologies Inc., the building was selected as a real-world case study to demonstrate the ability of low-E retrofit glazing systems to improve the energy efficiency of older commercial buildings. The study examined four unoccupied perimeter offices in the building, two facing east and two facing north. One office in each pair was retrofitted with RbB, while the other was left untouched.

According to project manager Thomas Culp, of Birch Point Consulting LLC, the renovated north-facing office saw a 33 percent reduction in total energy usage and the east-facing office saw a 53 percent reduction. “We are compiling results for the whole building’s performance to compare them with prior years’ usage, but these results for the building’s perimeter offices are compelling in both heating and cooling performance,” he says.

The DOE estimates inefficient windows account for as much as 25 percent of a typical building’s heating load in cold climates and 50 percent of the cooling load in warm climates. “After we evaluate all the numbers, we expect the RbB system to have made a significant improvement to the entire building?s energy performance,” Culp adds.

Culp said he sees great potential for low-E window retrofits, such as the RbB system. “There are countless older buildings with single-pane windows that waste a huge amount of energy,” he explains. “While results will vary from location to location, 400 Market Street in Philadelphia was an ideal testing environment to determine both heating and cooling benefits.”

Carolyn Pfeiffer, property manager for Kaiserman Company, the owners of the building, agreed. “400 Market Street is representative of many older commercial buildings, both larger and smaller, across the country,” she says. “This is just one of our properties that we have updated with the RbB system and we are excited by the results. RbB is suited for all weather conditions as the results from the energy study show, and it’s a cost-effective alternative to other window replacement scenarios.”

Because the RbB system is a pre-assembled IGU that is installed to the existing interior window surface, it also has the advantage of being much faster and less disruptive to install than a traditional rip-out-and-replace project.

“Our tenants were able to stay in their offices, and we were able to save the time and costs associated with temporarily relocating them,” Pfeiffer adds. “Tenants also have shared comments about reduced street noise and indoor comfort, and the maintenance staff has noted reduced cycling times on the boilers along with the ability to lower hot water set points.”