Window Manufactures settle with FTC over false claims. Some truths about Windows.

By
Home Inspector with Certified Structure Inspector IOS #1730, EA #30

We all love windows in our home.  Often time windows are sold as an energy saver upgrade. New windows can save some money in energy cost but most of the time they don’t pay themselves back in Energy savings like other energy retrofits can. People often take in to account the possibility of energy savings when buying windows. This was due to some marketing done by 5 big window manufactures. These 5 window manufactures just recently settled with the FTC over false claims of large savings.

http://ftc.gov/opa/2012/02/windows.shtm

A good rule for window change out is the condition of the old window. Single pane wood or metal windows that are deteriorated, damaged or inoperable are a better candidate than double pane aluminum windows in good conditions. If windows are in good condition storm windows are another usually less expensive option. If you replace a double pane window with another double pane window your gain is mostly in the frame.  Two panes of glass don’t always insulate twice as good as a single pane.  In older leaky windows you can have air leakage around the window. This is another area you can gain some efficiency and comfort. When choosing to upgrade windows some things to consider are aesthetics, function, and security. These reasons are often more compelling than the energy savings.Window Performance Sticker

When looking at windows there is a rating supplied with all new windows. The sticker on the window tells its performance rating. The two most important are the SHGC and U-Factor. The Solar Heat Gain Coefficient is the amount of heat gain that is allowed through the window. In a colder area like ours this allows the suns heat to warm the inside of the home.  The other is the U-Factor. This is a rating from the National Fenestration Rating Council. This rating gives the overall insulation value of the window. It can be related to the R-Value of insulation. During an Energy Audit when new windows are desired by the home owner these are the factors I use to calculate pay back of the windows from the old to the new. The cost of the window and are factored against the Energy Savings per year to find the payback in years.  The smaller the U-Value the better, the average double pane window has a U-Factor of .87. The best triple pane window I can find available has a U-Factor of .16. These windows are significantly more expensive than the average window.

Some standard values for windows are

Window Type

U-Factor

R Value

Single Pane Metal

1.310

.76

Single Metal W/Storm

.982

1.02

Single Pane Wood

.9

1.11

Single Wood W/Storm

.675

1.48

Double Pane Metal

.87

1.15

Double Pane Wood

.49

2.04

Double Pane Vinyl

.46

2.17

Triple Pane Vinyl

.36

2.78

Best Triple Pane Available

.16

6.25

 

Even the best window available falls short of an insulated wall.  But windows that have a high SHGC that are placed in the right part of the home can provide 8 watts of heat or more.  While new windows will give you a small amount of improvement in energy savings your money might be better spent in another area. How do you know if that is the case in your home? You hire someone like myself to perform a whole house energy assessment. Using advanced techniques, specialized software and high tech equipment your homes Energy Performance is rated and areas that need improvement are pinpointed.

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