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Historic Window Follow-up

It seems appropriate that I give a little rebuttal to the story I reprinted last week on historic windows (here).  I’m a supporter of Indiana Landmarks.  I can’t argue that preserving old windows is a green solution.  Keeping them out of landfills is just one example of this.  Unfortunately there are other issues.

It’s worth noting that Daniel tested old windows with storm windows installed.  Many older windows don’t have storm windows and some that do have storm windows that fit poorly.  It’s also worth noting that he was testing glass to glass.  I think he’s right that the extra air space between the inside window glass and the storm window glass made a difference.  Most of the new window manufacturers will tell you the same thing.

But a window is an assembly, not just the glass.  Daniel might have gotten different results if he had tested around the perimeter.  New windows have thermal blocks to prevent heat transfer which old windows do not.  He might have gotten different results if he had tested around the outside of the trim.  New windows don’t have ballasts or their associated cavities in the walls.  When we install new windows we fill those voids with insulation which is nearly impossible to do with a window in place in a finished wall.

And one more thing about storm windows…  They generally come down in the Spring and don’t go back up until Fall so we can enjoy the fresh air.  Heat transfer is just as important in the heat of the summer when the air conditioner is running.

Old Window with cracking Lead Paint

Another big issue with old windows is lead paint.  I attended a lead safety course and they emphasized that old windows with lead paint were a prime producer of lead dust.  The old double hung windows are often painted on the sides of the sash as well as in the window frame track.  Friction across these painted surfaces as the windows are raised and lowered produce lead dust which is easily inhaled, absorbed or ingested if it gets near food.  Stripping an old window such as the one in the picture to the right is a time consuming and expensive process, particularly when lead safety practices are observed.Window location is also important.  New building standards require tempered glass when glass is installed less than 18″ above the floor or adjacent to stairs.  Older windows are exempt from this requirement, but that doesn’t make the safety issue that caused the rule to be promulgated go away.

There is also the issue of seals.  We’ve all seen old double hung windows with foam stuffed into the joint between the sashes to prevent air infiltration.  New double hung windows have seals at those cross points.  Even with those, they can’t compare with new casement windows that have the locking mechanism that pulls the sash tight against the seal.

All in all, there are some benefits to salvaging old windows.  New windows never provide the same look or have the authentic trim.  Often it is cost prohibitive to install new windows with true divided lights.  There are many reasons to preserve historic windows.  It’s important to understand all the cons that go along with the pros though.

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