According to the United States Department of Energy, buildings use about 76 percent of electricity in the US and are responsible for about 40 percent of all direct and associated greenhouse gas (GHG) emissions in the country. This means that reducing energy consumption from buildings is an essential step for the US as it makes its way towards net-zero emissions. A discarded window innovation from the 1990s might just help it get there.

Using better-insulated windows can go a long way in improving a building’s overall energy efficiency. And that’s exactly what a team of researchers at the Lawrence Berkeley National Laboratory tried to achieve back in 1991 when they designed a “thin triple-pane” glass window.

Breakthrough window design

According to Scientific American, the improved-efficiency window design had the potential to cut annual energy use for heating buildings by 39 percent and slash air conditioning spending by 28 percent. The key component in the design was adding a thin layer of glass between the usual two and sealing it with an inert gas.

The breakthrough, however, was abandoned by US window manufacturers because they found it too expensive. “It was un-manufacturable,” Robert Hart, a Berkeley Lab researcher involved in the design, told Scientific American. Equipped with perseverance, the Berkeley team decided to give it another try in 2003.

This time, however, they relied on the help of television and cellphones companies. These firms had managed to drive down the price of ultra-thin glass because it was such a key component in their production methods. Then in 2019, the team decided to approach several US window companies once again.

One of these window manufacturers was the Alpen High Performance Products Inc. of Louisville, Colorado. Alpen was already working on a three-pane window, but the company decided to tweak its design after seeing the Berkeley prototype and learning that the price of thin glass dropped by about an eighth of its previous cost. The change resulted in a much superior window.

The upgraded window design was cost-effective enough that it drew the attention of the California Energy Commission, which granted the Berkley team a grant to replace all of the double-pane windows in every new home in Fresno. The state then awarded the researchers a second grant of $1.85 million to help them evaluate the economic effects of the triple-pane window design in three low-income communities.