Matt's restored 110 year old windows with energy efficient weather stripping
Owners of old homes are led to believe that if they want to make their homes more energy efficient they need to replace their old windows. This week we proved them wrong. We were able to reduce the air leakage in our 110 year old, double hung, single pane windows by an astonishing 70%!
Surprisingly, about 1/3 of home heating and cooling costs come from energy loss, not energy use! If you spend $1000 to heat your home, $330 of that is going out the window.
Windows in old homes are among the biggest losers. Add up those gaps in the sashes, the holes in the pulleys, and the tiny cracks in the glazing and it’s like leaving a window or door wide open all year long!
When Kelly and I bought our house and launched Greenovation.TV
, the windows were in pretty bad shape. None of them could be opened. They had layers of paint, they were swelled into the tracks, most had cut sash cords, a few had old felt strips stuck in between the sashes, and some had broken or missing sash locks. And they all leaked — A lot.
Before we did any work to our windows, the non-profit Clean Energy Coalition helped us run a diagnostic blower door test to see how much air leakage we had in the house. Our baseline was a very, very leaky 4400 cubic feet per minute (CFM at 50 pascals). That is typical for an old house.
Silicone bulb weatherstripping inserted into a kerf cut into old window
Next, Lorri Sipes from Wood Window Repair Company, and some students from our window repair workshop helped us restore our windows. During the restoration we put silicone bulb weather stripping in the sash top, bottom and meeting rail and tacked a bronze weatherstrip into the jambs. Then, we added tightly sealed Trapp storm windows with low-E glass. This gave us the benefit of modern glass and the effect of having double pane windows.
Finally, it was time to do a follow up blower door test to see how well the windows perform. Drum roll please . . . . 1300 CFM at 50 pascals - down from a pre-restoration of 4400 CFM.
Robertson's Screen & Storm Company Installing Trapp Storm Windows with Low-E Glass
Restoring your old windows as DIY project will cost about $400 in materials; if you hire a pro to restore the windows for you, it will cost about $400 per window. New windows cost about double and will need to be replaced again in 25 years.
With continued care and maintenance, our restored windows should last us another hundred years, keep us cozy inside and help us meet our goal of net zero fossil fuel energy.