Today, it’s easy to take big glass windows and doors for granted, whether they show up in commercial buildings or in our homes. But this use of glass is, at its core, a technological breakthrough that changed how we live and how our buildings work.

As Thomas Leslie explains, insulated glass shaped the look of the 20th century. Big but poorly insulated glass windows went out of fashion as electricity allowed for the production of artificial light. Builders needed a new way to install windows that let in natural light, but also controlled heat.

Insulated glass was that solution. As the above video shows, the invention of a branded glass, Thermopane, and its immediate competitors, led to the landscape we recognize today.

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