Window film boosts library’s energy efficiency

The latest energy-efficiency improvement in D.H. Hill Library isn’t likely to be noticed – even by those looking directly at the cutting-edge technology.

New high performance film has been applied to 770 south- and southwestern-facing windows in the library’s North Tower and Erdahyl-Cloyd Wing. The ceramic, nearly transparent film reduces the rate of heat transfer through the windows, helping to maintain optimal indoor temperatures year-round while reducing the HVAC load and the building’s energy consumption.

“We are expecting the film to cut the building’s annual energy costs by at least 10 percent,” said Claudia Powell, a program coordinator with NC State’s Energy Management.

Powell anticipates the most dramatic results will be felt in the Erdahl-Cloyd Wing, where the windows are single-pane. She conducted pilot testing with the film in this location over winter break. For that 10-day period, data loggers recorded temperatures in side-by-side rooms – one where the film had been applied to windows and one where the film had not been applied. The room without the film reached more than 100 degrees on several afternoons while the room with the film experienced less dramatic temperature swings.

“The pilot was very revealing with the film creating up to a 30-degree temperature differential at times,” Powell said. “The test confirmed that the film will enable us to reduce HVAC load and help keep building occupants more comfortable.”

In addition to reducing heating and cooling costs, the film also blocks ultraviolet rays that are harmful to human skin as well as furniture, books and other indoor items.