Some recent discussion on new verses old windows motivated me to post these infrared images. The dark blue spot at the bottom of all three windows is cold air flowing by the window seals. The first two windows, one a casement and one a double hung, are newer thermal pane windows. They are from the same home.
The glass is in fact performing fine. You will notice the glass temperature is close to the adjacent wall temperature.
What these images show is a more common problem with windows, air infiltration.
Just to demonstrate how little difference there can be from old to new windows look at the last image from the same home.
This window is an 80 year old single pane window with a storm in place. It is leaking air along the entire bottom of the sash. You will also notice air coming through the trim molding. That is probably because there is no insulation between the window frame and house framing.
No insulation is common with old as well as newer windows especially replacement windows.
The glass is cooler than wall by about 5 -6 degrees as opposed to the newer window where the differential was 2 - 3 degrees. The difference will become greater as the outdoor temperature drops.
Should the old window be replaced? Absolutely.
Will the homeowners save lots of energy?
No, but they will be more comfortable.
The estimated cost to replace the window, $352. The estimated yearly savings, $10.
Is there a return on investment? No.
It would take 35 years to break even and 36 to begin seeing a return. Of course as energy costs increases the ROI time will decrease.
Window replacement in the context of energy savings would best be described as a wash.
What the energy audit revealed for this home was insulation and air sealing were the best and most cost effective upgrades. The windows placed dead last.
Next time you see an ad or receive an offer for replacement windows promising 20 - 40 % energy savings, be skeptical. Be very, very skeptical.
James Quarello
SNEC-ASHI President
NRSB #8SS0022
JRV Home Inspection Services, LLC
To find out more about our other high tech services click on the links below:
| Learn more about our Infrared Thermal Imaging & Diagnostics services. | Learn more about our energy audits, the Home Energy Tune uP®. |
Susan, Just trying to spread the word.
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