Oak Ridge National Laboratory researchers demonstrated that window shades with a cellular or honeycomb structure provide higher energy savings during winter compared to generic venetian blinds and can save millions of tons of carbon emissions.

Windows contribute to energy demand in residential homes because they let heat escape; coverings can improve insulation. In a study, researchers compared the performance of three single-cell and two cell-in-cell-construction cellular shades with that of generic horizontal venetian blinds. The shades were installed from December to March for two heating seasons over windows in adjacent, identical second-floor rooms in a home in the Southeast United States.

"The room with the cellular shades achieved up to 24% heating energy savings," ORNL's Mahabir Bhandari said. Additional energy simulations predicted how the shades would perform in different climate zones. "Nationally, carbon emissions could potentially be reduced up to 3 million tons assuming a 20% penetration rate of cellular shades in residential buildings."

The study is published in the journal Building and Environment.