There's nothing worse than windows that don't provide proper insulation. You feel it when the weather is cold. Thin single-pane windows—or even balky double-pane windows—seem to radiate with cold.
That's just the glass area. If you've got poor or non-existent insulation around the window framing, the entire window area feels like the sash is open. No wonder your furnace constantly runs and your bills run higher than expected every month.
Is it time for new windows? Possibly. One way to justify the cost of new windows is to tell yourself that you can recoup the cost with the energy savings you will enjoy. But is this even true?
Claims: New Windows Pay For Themselves
Window replacement means removing the existing sashes (the framed glass) and installing a newer but slightly smaller set of sashes set within its own window frame, which then is set inside of the home's window frame. Usually, insulation around the frame can be added, too.
Window replacement is a very expensive project. The national average for replacing a window is $650. On the face of it, that might sound like a manageable cost. But when you consider that homes can have ten windows or more (usually more), that cost suddenly leaps to $6,500.
One way for some window retailers and local window installation companies to try to sell their products is to claim that the cost of the windows will be made up by the savings in energy costs.
Most major window manufacturers such as Pella and Andersen do not make these claims. Instead, they concentrate only on energy saved without factoring in the issue of the windows' cost.
So, how would this argument work?
A salesperson might say that government research shows that you can save $126 to $465 a year in total when replacing windows. If each window costs $650 and you use the higher of the two figures—$465—you have nearly paid for the windows in ten years. At that point, you're only short $1,850. To fully cover the cost, it would be about 14 years.
Considering that many windows come with warranties ranging up to 20 years for glass and 10 years for components, you're still in a safe zone of ownership.
While these figures are basically right, they can get inflated in certain ways so that they bear little resemblance to reality.
New Windows Cost-Benefit Analysis
New replacement windows will save you energy and provide greater comfort within the house. This much is true. The Environmental Protection Agency (EPA) EnergyStar program estimates that the average U.S. home can save $126 to $465 a year when replacing windows, but this is for single-pane windows, which fewer homes have today.
The figure is lower for double-pane windows: $27 to $111 a year with EnergyStar-qualified replacements, not new construction windows.
The argument is further weakened when you consider that the cost savings numbers tend to be at the top of the scale—$465 or $111—while the cost of the windows is often minimized.
Also, it is important to remember that the EPA figures are per year. By the EPA's estimates, the absolute most you can save over 30 years, or the length of a typical mortgage, is $13,950. That figure is for New England homes, based on replacing single pane windows with double pane windows.
Shanon Peterson Wasielewski, in her paper for the Washington Department of Archaeology and Historic Preservation "Windows: Efficiency Facts and Myths" did a cost/benefit analysis. She used the EPA software, RESFEN 3.1, for a two-story brick home in Nashville, Tennessee. In her scenario, the house has 20 windows and it cost $8,000 to replace all the windows. Wasielewski even acknowledges that $8,000 is an "extremely low estimate."
By her estimates, it would take 70 years for the energy savings to help you recoup the cost of the windows. Seventy years takes you well beyond both the warranty period for most windows and their practical life expectancy—as well as your own life expectancy.
Cost Savings Real or Not?
Except in extreme scenarios, replacement windows will not pay for themselves in energy savings in any appreciable sense.
For there to be any hope of making up your investment, the total cost of the windows must be very low (possible if you replace the windows yourself); current windows must be very bad (single-paned and not energy efficient); and you live in a cold climate (Maine, not Florida).