Behind the Scenes: How a Window Gets Made

by on May 5, 2013

Two workers working with wooden pieces in a factory.
This spring, I had a chance to tour the manufacturing facility at Andersen Windows Corporation in Bayport, Minnesota. Bayport is a small town (about an hour from Minneapolis) on the banks of the scenic St. Croix river. It’s a beautiful setting, and one Andersen has enjoyed for a hundred years. Preserving the river is really important to the company, and one reason they take great care to produce their windows and doors in an environmentally-conscious way. Read on to see what I learned about how windows get made, and watch my video tour!

In theory, a window’s not a very complicated thing; it’s like a picture frame, with glass inside. Picture frames are easy, right? You’ve probably made some; just four pieces of wood, four 45-degree miter cuts, and some glue or fasteners.

In practice, though, windows are a lot more advanced. Andersen’s been making them for a long time, and the process has changed a lot since the beginning. That simple wood frame is now made of engineered wood which is recycled from waste scraps. Why? Well, the frame isn’t visible in the finished install anyway, and the engineered lumber (little scraps of wood trimmed and glued together) is actually stronger than solid wood. This reduces waste and makes a better window.

A bunch of two by fours with weird cuts in the ends of them.

So, if the engineered lumber isn’t visible in the final product, what is? Well, on windows that are ordered to have exposed natural wood, it’s just that … solid wood! But turning huge, sixteen-foot rough-cut lumber into small, precisely die-cut window components is also a tricky process, and one that can be done with an eye toward sustainability.

At Andersen, that rough lumber comes into the factory on a train, and then goes through a machine that optically scans the boards for maximum yield. Wait…what?

Technical hacks to follow in your computer.

Yep; they have a huge scanner (like the one in your office) that looks at every single board and, using computer algorithms, figures out which sections of the wood are usable and which ones are not. It also comes up with a cutting plan for how the automated saws (first a rip-saw, then a crosscut-saw) should cut the board to get the most good, usable wood out of it. 

Even if you’re using recycled wood for the interiors, and being super-efficient about how you use and produce the solid wood components, there’s one thing you can remove from any process that involves cutting wood. Sawdust.

If you’ve ever done so much as a minor woodworking project in your basement or garage, you know a saw produces a lot of sawdust, even for short cuts. So, clearly, all of Andersen’s operations must produce a tremendous amount. But, interestingly, looking around the factory, you don’t see it anywhere. Why?

Because the crown jewel of the factory’s sustainability efforts is a plant-wide sawdust collection system. A series of tubes (no, not that kind) that pick up sawdust from every cutting station in the facility making the factory floor sawdust-free! But what to do with all that waste (not to mention the bits and scraps of waste wood)?

An industrial set of structures and buildings are interconnected with pipes and vents.

A lot of the sawdust (or wasted wood, which gets ground up into sawdust) gets turned into Fibrex, a material Andersen invented which is a combination of vinyl and wood. It’s about 40 percent wood fiber, 60 percent thermoplastic polymer (vinyl). That makes it stronger than vinyl alone, rot and weather-resistant, and a 700-times-better insulator than aluminum (Fibrex is mostly used in exterior window cladding, where you’d normally see aluminum). 

A handle holding tiny pebbles.

The rest of the sawdust (yeah, there’s a lot) gets sent to Andersen’s private steam generating facility. Opened in 2007, this plant burns sawdust as its primary fuel, and supplies the heating and cooling energy needed for the entire 2.5-million square foot manufacturing facility.

An industrial piece of machinery contains fire and is made with pipes, nuts, and bolts.

The plant also captures thermal energy from warm water discharged from the Xcel Energy power plant located just upstream on the St. Croix; that means the water that goes back into the river isn’t as hot (which is better for the river’s ecology).

Windows are ubiquitous; they join the insides of our homes to the outside world. And although you can think of them as just simple openings filled with glass, there’s a lot more to them than that. I really enjoyed getting a backstage look, and it was great to see a company taking great pains to incorporate sustainable values into their production processes.

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