How much will you save on your heating bills by installing new windows?

Good question!

You may have heard claims of 40% savings “guaranteed.”  Such claims or guarantees are usually just lures or gimmicks to hook consumers into a quick deal. 

The fact is that 40% savings may be possible in some cases, but it depends on your  situation—the type of windows you have now, how many windows you have,  the performance of your new windows, and several other factors all affect potential energy savings. 

Too complicated?  Weathervane is here to help!  Let us answer your questions and make recommendations.  

#1.  What type of windows are being replaced?  If your old windows have aluminum frames and single-pane glass, you have the biggest opportunity for savings that could amount to 40% depending on the other factors listed below.

#2.  How much window area do you have?  The more glass area you have per square foot of living space then the more heat is lost through the windows.  If you have lots of windows, then there’s a better chance that you can save up to 40%.

#3.  What is your exposure?  If a significant number of your windows face north or are shaded by overhangs, trees, or nearby buildings, then you are not getting much “free” solar heat from direct sun through your windows.  High-performance windows will have a greater benefit under these conditions.  On the other hand, if you have a large, southern exposure, then you are already getting the benefit of some “free” solar heat.  New windows will still save you money, but probably not 40% of your heating cost.

 #4.  What is the performance level of your new windows?  Most windows sold in the Northwest meet Energy Star requirements.  Many exceed them.  Super-high performance windows, such as triple-pane, exceed them by a lot.

Energy Savings Estimates.  Here are three estimates of  savings on heating costs from several types of windows—.

Conditions:      A 2,000 sq.ft. house with 300 sq.ft. of window area that is equally distributed on 4 sides—east, west, north, and south.   The original windows are aluminum frame, single-pane glass,

     Case #1:    Switching to…double-pane low-E,  wood or vinyl windows,
U-factor 0.35                Savings = 25%

     Case #2:    Switching to…double-pane low-E, wood or vinyl windows with warm-edge spacer and argon gas,
U-factor 0.28                Savings = 27%

     Case #3:  Switching to…triple-pane low-E, wood or vinyl windows with warm-edge spacer and argon gas,
U-factor = 0.19             Savings = 34%

So what about the “guaranteed”
40% savings??? 
It’s mainly a gimmick.  Like they say—be sure to read the fine print.  Most of these guarantees only promise to “make up the difference” in your energy savings for one (1) year.  If you were expecting to save $500 per year, but only saved $400 per year, then the "guarantee” pays you $100.  BUT, your windows will last 25 years or more.  Why does the “guarantee” only make up the difference for one year?

Don’t be taken in by an empty “money back guarantee!!!”  Companies that offer the best value usually don’t have to use gimmicks.  Remember these three rules when replacing your windows:

       Rule #1:  Get more than one bid!
       Rule #2:  Get more than one bid!
Rule #3:    Get more than one bid!

Tax Credit for Energy Savings.  Uncle Sam will give you up to a $1500 credit on your taxes for window replacement.  Make a note for your 2009 tax return!

Return on Investment.  New windows have been shown to have a 75% to 100% return on investment when a home is sold assuming what you paid for the windows and installation is reasonable (remember the three rules!).

Total it all up!  Imagine seeing monthly savings on your heating bill, a $200 tax credit,  and getting back 100% of your window purchase price if you sell your home!

A final tip:  Consider putting two types of glass in your house.  For example, use double-pane “high solar gain” Low-E where you get direct sun so that you maximize your “free” solar heat gain.  Then on the colder north or shaded sides, use windows with the lowest possible U-value, such as triple-pane. In this way, you “tune” your windows for maximum savings and comfort.