Although both R-Value and U-Factor values measure thermal performance, U-Factor values are more commonly used for windows and doors. Here’s how to make selections that will boost the U-Factor value of your window unit:

• Window type: Select the most energy-efficient type, like picture (non-operable) windows, where possible and consider casement and awning windows where operable windows are needed.
• Glass type: Select triple-pane glass where possible. The extra air space and opportunity for an additional low-emissivity (Low-E) coating contribute to better thermal performance. 
• Low-E coatings: Select the right coating or combination of coatings for your climate. Find out more about how to select the right Low-E coating(s).
• Avoid grilles: This is the best way to boost U-Factor values. However, if you want grilles, consider energy divided light grilles, which help reduce energy transfer through the glass. 

Triple-pane windows outperform dual-pane windows in both energy efficiency and sound abatement. 

To compare the thermal performance of one window unit against another, look at U-Factor values, which measure how well windows keep heat inside the home. Be sure you are looking at “whole unit” performance rather than “center of glass” performance. Whole unit performance measures exactly that — frame, glass, etc. — so it gives you the most accurate measure of the window’s thermal performance. Find thermal performance documentation for our products.

To compare the sound performance of one window unit against another, you can look at sound transmission class (STC) and outdoor-to-indoor transmission class (OITC). Find sound performance documentation for our products. 

Windows with triple-pane glass are generally more expensive. However, we offer triple-pane windows through a variety of product lines that are priced to meet a range of budgets. For the most affordable option, choose a 100 Series window with triple-pane glass. Understand more about pricing, or get the specific details you need to begin pricing your project by requesting a quote. 

These products are available with triple-pane glass:

• A-Series windows and doors are available with triple-pane glass.
• E-Series windows and doors are available with triple-pane glass.
• 400 Series windows and doors are available with triple-pane glass in select states.
• Select 200 Series doors are available with triple-pane glass.
• Select 100 Series windows will be available with triple-pane glass on October 20.
• All big doors, including Folding Outswing, MultiGlide™, and Liftslide Doors, are available with triple-pane glass. 

Find out more about triple-pane windows.