old windows

One of the common misconceptions in curbside recycling is that all glass is treated the same so you can recycle glass cups, light bulbs, and windows along with your bottles and jars. Believe it or not, your recycling company doesn’t want these items — and not just because they are likely broken.

Windows are an example of treated glass, and they’re much more difficult to break than a glass bottle. Glass manufacturers use different processes and materials to make container glass (bottles and jars) and treated glass. Treated glass is reinforced with chemicals to make it stronger and less likely to break. 

The process for recycling glass involves melting it in a furnace. Treated glass requires a much higher temperature to melt, so if window glass gets mixed in with container glass, it contaminates the entire recycling batch with chemicals that prevent use as recycled containers. While windows could be recycled if all of the glass being recycled were treated glass, windows are disposed of infrequently enough — outside of large building demolition projects — that most recycling facilities aren’t set up for it.

Reuse Windows When You Can

If you have windows that are still in one piece, try to donate them for reuse. One option is the Habitat for Humanity ReStore. ReStores accept and resell all sorts of construction materials, and your local store may accept windows. Stores are more likely to accept your windows if they’re newer and energy-efficient, as customers will want such windows for new applications.

Old windows are an excellent material for a variety of DIY  projects — particularly if your window’s frame is intact. You can make bulletin boards, jewelry organizers, or even a headboard.

Window Recycling Options

In the recycling industry, windows are classified as construction and demolition (C&D) waste. The U.S. generates more than 500 million tons of C&D waste per year (more than twice the volume of our packaging waste), so many states have stepped up to address this issue by providing lists of C&D recyclers.

For instance, CalRecycle maintains a list for the state of California. You can contact your state solid waste agency to see if they can refer you to a company that accepts windows for recycling.

Beyond Recycling

You may be able to upgrade your old windows, the options are expanding with technology.

A company called SolarWindow goes one step further: It lets you turn your windows into solar panels. The U.S.-based company provides a spray-on technology for any glass surface that allows it to generate renewable solar energy, and claims that the technology achieves payback within one year in energy savings (compared to five to seven years for traditional solar panels).

The biggest catch when it comes to windows is that you’ll most likely want to recycle them when they are broken, and that’s when they have the least value in the recycling market. The injury risks of transporting broken glass negate most of the value in the material, so if you’re planning a house remodel, make sure the old windows stay intact.

By Trey Granger

Trey Granger is a former senior waste stream analyst for Earth911.