Pane Gains

Window Glass Goes High Tech

By Joel Nelson on Nov 22, 2024 in News

Much of the discussion about energy efficiency in commercial and residential buildings focuses on heating and cooling systems. But windows, which account for more than half of a modern skyscraper’s exterior surface area, are earning their share of attention in the search for smart solutions for buildings.

Commercial buildings account for about 40% of carbon emissions. Glass traditionally used in skyscrapers easily transfer heat from the inside to the outside, leading to higher energy consumption for heating and cooling.

In response, advanced materials and engineering are driving a “revolution” in the building industry, “one that is set to transform the way we think about construction and energy efficiency. At the center of this revolution lies glass,” says Görkem Elverici, CEO of Şişecam, a leading glass manufacturer based in Turkey.

For example, low-emissivity (low-e) coatings incorporate an extremely thin coating of silver, zinc or indium tin oxide to reduce heat loss and heat gain through windows. They also help prevent the damaging effects of ultraviolet light on furniture, floors and other items.

Insulated glass units often fit into existing window frames, eliminating the need for costly redesigns and retrofits.

Other energy-efficient windows contain sealed layers of argon gas, which combine with low-e glass and vinyl framing for greater comfort and energy cost savings.

Secondary glazing involves improving a window’s insulation with an additional windowpane. With this technology’s potentially not yet fully realized, the U.S. Department of Energy (DOE) is sponsoring prizes valued at $2 million to encourage innovation of high-performance, cost-effective secondary glazing systems for commercial building windows. The prizes will be announced by May 2026.

“Less than 1% of commercial buildings get full window replacements each year because it is so expensive and disruptive for occupants. Secondary glazing systems can help solve this problem,” says Jeff Marootian, the DOE’s principal deputy assistant secretary for energy efficiency and renewable energy.

Windows were added to the ENERGY STAR® program in 1998. Recent updates to ENERGY STAR standards and building codes in some jurisdictions increase the urgency of elevating performance standards.

The DOE’s Building Technologies Office estimates that improved window performance could reduce the country’s annual energy use by 1.7% and CO2 emissions by 1.9% by 2050.

Ongoing challenges include high energy consumption associated with extracting and processing the natural resources used in manufacturing glass. Some manufacturers are responding by increasing their use of recycled glass, instituting energy efficiency initiatives and making greater use of renewable energy sources.

“Inefficient windows are a huge energy savings opportunity,” says Marc Lafrance, a DOE technology manager. “The widespread adoption of cutting-edge novel window technologies can keep energy use and costs low while ensuring our comfort as well.”