Save Big Bucks By Restoring Your Old Windows & Making Them Energy Efficient

By: Matt Grocoff , Contributing Writer
In: Home Improvement Tips, Green Renovations
Matt's Restored 110-Year Old & Energy Efficient Windows

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

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 Storm & Screen Installing Low-E glass Storm Windows

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.


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  1. 11 Responses  to “Save Big Bucks By Restoring Your Old Windows & Making Them Energy Efficient”

  2. Karin Murphy
    Sep 29, 2016
    Thanks for this article! I've restored several old houses and hundreds of windows and it always pains me to see people spend thousands of dollars replacing their old wood windows that have character and charm with vinyl replacements that wont last 25 years, when their old windows could be restored with a little elbow grease. The last house I restored was 150 years old with over 30 original windows. The bid to replace (made by a well known window company) was 60k. I decided to restore and at the end of the day, I have windows that will last another hundred years and the reward of doing it myself. If only more folks would think twice before replacing.
  3. Brian
    Nov 6, 2015
    Nice story. However, you failed to mention, although it's obvious, that after using your solution. your windows won't open. I'm looking for a solution that will allow me to use my windows as windows - meaning they will open, as designed.
  4. Travis Simons
    Feb 6, 2015
    It seems like it is getting to be more poplar to repair your windows then replace them. My uncle saved a lot of money doing this at his house. Then in the long run it made his house more energy efficient also. He is so glad that he repaired his windows to get them back up to date. http://www.glassimpressionsinc.com/residentialservices.html
  5. peter henin
    Aug 29, 2011
    you did a great job...but I have query like is that any possible to repaint the window will stop the energy loss...
  6. Aug 29, 2011
    Great work, Matt and Kelly!
  7. lucy
    Aug 29, 2011
    Great case study. check out this study that speaks to energy savings of high rvalue windows vs solar and other measures http://www.Seriouswindows.com/highrvaluestudy
  8. Aug 29, 2011
    Here's a link to the full Case Study: http://www.scribd.com/doc/35303527/Case-Study-Window-Restoration-Energy-Efficiency-for-110-Year-Old-Net-Zero-Home
  9. Aug 29, 2011
    Jonny - Restoring old windows and using storms is usually much, much more cost effective and affordable. I'll be posting our case study soon which has some more details about how we added weather stripping to the old windows. But, if you get high-quality storm windows that are well sealed and have Low-E (low emissivity) glass, you will achieve as good or better energy performance than many new windows out there. For the storms, make sure you look for welded miters in the corners, and tight weatherstripping on all of the moveable parts. The storms are put in place with a caulk and screwed to the inner frame of the window. They are low profile and can be removed, so they are suitable for most historic districts. Our storm windows are triple track. Meaning that there is a top and bottom glass with a screen. They can all move up and down and can be positioned where you like. They are easily removable from the inside for cleaning. Our neighbor down the street moved into a historic home where someone had illegally removed the historic windows and replaced them with cheap vinyl windows. The former owner probably thought they were getting a great deal and saving some energy. But, their house is actually less tight than our house with our restored old windows. We both had blower door tests done and our old windows out performed their "cheap" new windows by about 30%.
  10. Jonny
    Aug 29, 2011
    Aren't the new storm windows you installed, just like adding new windows? Are they fixed or operable. We have an old house and were considering getting new windows and using the tax credit, but maybe we'll just get storm windows..more details, please!
  11. Aug 29, 2011
    I never have the patience to repair old windows other than a new pane and some glazing now and then. I have thought it would be cheaper in the long run with materials and labor to just rip out the old and replace with the new. There are windows you can get now that look like the old antique windows.