Purchasing replacement windows

Published January 1, 2012

Q:  I can feel cold air coming from the windows on the west side of my home. The windows are wood with a storm glass on the outside. A contractor told me he could replace all the windows and I would save enough money on heating bills to pay for the replacement in no time. I really don’t have the money right now to replace all the windows and was wondering if replacing a few at a time is a good investment.


A:  If your home has storm windows you most likely have double hung windows with a single pane of glass.  Double hung means the bottom and top portions of the window slide up or down.  Awning and casement type windows open out and storm windows would block the opening of the window.  It is likely that your windows will experience air leakage around the window’s trim, but that can be fixed by removing the trim, adding a spray-on foam insulation between the window and house frame and then replacing the trim.  You should also make sure the windows have weather stripping at all edges and the locking system holds the upper and lower sashes tightly together when closed.  You may still feel as though there is air leakage when you hold your hand next to the glass.  The air between your warm hand and the cold window glass is trying to equalize and most people will mistake this transfer of heat-to-cold as an air leak.  Even replacement windows will have glass that has a cooler surface temperature when compared to the air in the room. Replacement windows are an excellent choice as an upgrade, but it will take a while to recoup your initial investment.  Over time a properly installed foam core filled, vinyl framed window will produce some savings.  If you choose a triple pane window with a low-e coating, your energy savings should be greater, but so will the costs of installation. As an example, a single pane window has an estimated R-value of 1.0 (the higher the R value the better the product will resist heat transfer).  Add a storm window to a single pane window and the R-value is increased to 2.0.   A double pane window with argon gas between the two panes has an R-value of 3.0 and a triple pane argon gas filled window has an R-value of 5.0.  When comparing R-values remember that a typical 2x4 stud wall, properly sealed and insulated, has an R-value of 13.0.  You can replace one or more of the windows at a time, but the costs per unit will be significantly more, which will reduce your opportunity for energy savings.


C. Dwight Barnett