Urban Natural Homes July 24, 2014

The History of Windows


With all the progress made in building technology to date, nothing has the potential to change the appearance of our homes more than new window technology. We now have the ability to create wide expanses of glass, opening up to the outdoors and nature like never before, while still conserving energy and our precious resources. Understanding the history of windows and how we got where we are today sets the stage for a wide range of topics including how windows fit into the larger picture of new building technology, energy efficient remodeling and upgrades, and whether or not to replace older/vintage windows. It also shows the incredible progress we’ve made in window technology in just a few short decades. So here goes – a brief overview of the history of windows.

The earliest windows were in fact just holes in the wall, sometimes covered with animal hide, cloth or wood. Romans were the first to use glass for windows, but they weren’t windows as we know them today. They were more like blown glass jars that were flattened into sheets so that they still had a circular striation pattern throughout. Incredibly enough, it was over a millennium before window glass became transparent enough to actually see through, and it wasn’t until the early 17th century that glass became common in the windows of ordinary homes. Single paned glass remained the standard until the mid-1970’s when world politics drove the price of oil to historic highs and the US Dept. of Energy did a study determining that approximately 25% of home heating costs were covering the heat lost through windows. This gave rise to the multi-pane window industry, the first step towards energy efficient windows. Multi-pane windows use the space between two or more layers of glass as an insulating layer, which is filled with argon or some other inert gas, to improve its insulating properties. As the industry progressed, manufacturers learned that aluminum frames were poor insulators and they began to look towards other materials including vinyl and wood-vinyl composite frames. Toward the end of the 1980’s, low-emissivity (low-e) glass, which uses a thin layer of metal oxide to create a barrier to infrared radiation, began to be incorporated into energy efficient windows. Low-e glass allows visible light to pass through, but keeps heat from escaping. As we progressed into the 21st century, researchers continued to expand the efficiency of windows through developments in triple paned windows, new coatings that change window transparency based on outdoor conditions, and further research into framing and spacing materials.

With the huge advances made in window technology, energy-efficient windows are of course a no-brainer for new construction. But are certain types better suited for each project? And as the vast majority of homes in our area are not new construction, but already existing homes, the more important questions may be: Should I replace my old windows with energy efficient models? Is this the first, or most cost effective, step to take towards energy conservation? How will new windows affect the historic integrity of my home? And are there alternatives to full window replacement? Stay tuned for discussions on these topics and more…