The 6 Most Important Thing to Remember When Comparing Vinyl Windows


Vinyl is either newly-made (a.k.a. Virgin vinyl) or re-ground (a.k.a. recycled). Both are virtually maintenance-free. But the make-up of the vinyl is not as important as the thickness of the vinyl. Vinyl thickness is a good gauge of quality. If cross-sections of the competing windows are available, take a look at the frames. Measure the vinyl thicknesses if possible. Thicker and heavier is almost always better but realize that it may cost a little more too. If you think you’ll need windows of larger stature, ask about the use of metal reinforcements inserted inside the window’s frame to improve its strength and rigidity.


The corners of vinyl windows can tell a huge story. Many vinyl window manufacturers use a technology called fusion-welding, which basically fuses the corners together to form a nearly unbreakable and impenetrable joint. Other vinyl manufacturers have corners which are screwed together or chemically welded, which functional but could possible leak over time. 


It’s quite easy to compare energy-efficiency thanks to the National Fenestration Ratings Council® (NFRC). See right.

The NFRC is a non-profit organization created by the window, door and skylight industry. Its primary goal is to provide accurate information to measure and compare the energy performance of window & door products. While the NFRC does NOT distinguish between a “good” window and a “bad” window, set minimum performance standards or mandate performance levels, it has directed window & door manufacturers to display their product’s performance by implementing the use of stickers on residential windows and doors. 

A typical NFRC label looks like this. See right.It allows you to easily compare the performance levels of competing windows. An NFRC label contains 4 categories and corresponding test values. While each category has an official definition, here are the laymen’s descriptions. 

  1. U-Factor: This is also known as the U-Value. The U-Value measures how well a window or door prevents heat from escaping. Remember: Lower is better when comparing U-Values. 
  2. Solar Heat Gain Coefficient (SHGC): SHGC measures how well a window or door blocks heat caused by sunlight. SHGC is expressed as a value between 0 and 1. Remember: Lower is better when comparing SHGC. 
  3. Visible Light Transmittance (VT): The VT measures how much light comes through a window or door. VT is expressed as a number between 0 and 1. The higher the VT, the more light being transmitted 
  4. Condensation Resistance (CR): CR measures the ability of a window or door to resist the formation of condensation on the interior surface of that product. CR is expressed as a number between 0 and 100. Remember: the higher the CR rating, the better.

It’s important that when you use the NFRC sticker to evaluate windows, that it’s a true “apples-to-apples” comparison. Don’t compare vinyl windows with wood windows. Don’t compare windows with doors. Most importantly, don’t compare a window with standard glass to a window that has specialty or Low-E glass. Different glass types can make a huge difference in the values shown on the sticker and can skew the comparison. Always check the NFRC sticker. It will tell you the glass make-up of the product you’re assessing. If you’re not sure, ask.


If energy-efficiency is your top priority, look for products that carry the Energy Star® label.


Energy Star® is a government-backed program helping individuals protect the environment through superior energy efficiency. Two categories make up Energy Star® window and door requirements; U-Value and Solar Heat Gain Coefficient. 

Energy Star® divides the United States into 4 different climate zones. Those zones and their respective requirements are as follows:Energy-Efficient-Residential-Windows-Doors-and-Skylights-2_副本

Energy Star Performance levels

5) WHAT’S THE WARRANTY:As you can see, Energy Star® levels vary depending on where you live so make sure you know the zone in which you are located. Also keep in mind that some areas of the country require Energy Star® status so you will probably want to check your local building codes. 

Warranties are different so make sure you fully understand the coverages being offered to you. These are the questions you should ask:

  1. What kind of warranty is it? Window warranties are presented in a couple ways. (a) Broken down by window component (glass, vinyl, hardware, etc. ) (b) Given as “whole window”, meaning everything from top to bottom receives the same coverage. 
  2. How many years are the coverages? 
  3. Is it a “non-pro-rated” (manufacturer’s liabilities remain constant throughout the life of the warranty) or is it “pro-rated” (manufacturer’s liabilities gradually decrease during the life of the warranty)? 
  4. If you sell your home, is it transferable to the next homeowner(s)? 
  5. Some vinyl window manufacturers offer painted exteriors. If this is a product you’ll be purchasing, ask how long the painted finish is covered. 


The old adage “You get what you pay for” is usually very true when it comes to vinyl windows. There are many vinyl window manufacturers and pricing on similar windows from two different manufacturers can fluctuate by as much as 25%. There’s usually a reason for this price variation. When all is said and done, make sure you don’t short-change yourself by basing your choice solely on who has the lowest price.


National Fenestration Ratings Council®
Energy Star®
American Architectural Manufacturers Association