Q. I have old windows and want to replace them with something more energy efficient, but someone told me that keeping my old ones is actually a better idea.
A. At my company we're advocates of reusing anything existing as there is always a carbon cost to newly manufactured items. Windows however present some different issues. No matter how much carbon you save by keeping that old window unit, if it leaks something awful and heat is lost or gained through the single pane glass as if there were nothing more than tissue paper there, then you are neither doing your heating/cooling budget any favors, nor the world in general.
Upgrading your window system to a new unit that fits the character of your structure and is more energy efficient is certainly a good idea during a remodel. However in an existing home you need to remember, unless you are using a cheap retrofit unit, that the exterior cladding will need to be peeled back to properly install the new unit. This means the added cost of patching and painting. Luckily there are a couple of smart solutions short of replacing the whole window unit if you don’t have the budget or the inclination and the window itself is salvageable.
The first is to make sure the window fits tightly against the jamb, adding weather-stripping as needed so that there are no drafts. The next option is to replace the glass itself with more energy efficient glass of which there are a few options. Typically with older historic windows we use a laminated glass with a low e coating to create an improved thermal barrier without the thickness of the dual pane solution.
As always your approach needs to fit your budget and complement the existing design of the house. The bottom line is new windows may be necessary but there are also excellent options short of that.
