Are you ready to buy new windows?
Our Window Selection Tool is your shortcut to finding the best options for your home and climate, but here’s a window buying guide if you’re keen to shop around for what’s available near you. It includes a step-by-step guide to help you through the process and information about which energy-efficient ratings you should look for based on your location.
Learn more about what the ratings mean for different climate zones with this Complete zone guide
1. Meet the Energy Code & Look for the Energy Star
Windows must comply with your local energy code. Windows that are ENERGY STAR® certified often meet or exceed energy code requirements. To verify if specific window energy properties comply with the local code requirements, look for the NFRC label.
The ENERGY STAR logo typically accompanies a map similar to the one on the left that highlights which location the product is certified for unless it meets the requirements in all 50 states. In that case, it says “Certified in all 50 states”.
2. Look for Efficient Properties on the NFRC Label
The National Fenestration Rating Council (NFRC) label is needed to verify energy code compliance. The NFRC label displays whole-window energy properties and appears on all windows which are part of the ENERGY STAR program.
The NFRC label gives ratings for U-factor, Solar Heat Gain Coefficient (SHGC), Visible Light Transmittance (VT), and optionally Air Leakage (AL) and Condensation Resistance (CR) ratings.
4. Ensure Proper Installation
Without proper installation, even the best windows may not perform as expected. If you’re working with a contractor, ensure they are qualified. Window manufacturers often maintain lists of approved installation partners most familiar with their products, as well as maintenance guidelines to extend the life of your windows.
To aid in proper installation, the Fenestration and Glazing Industry Alliance (FGIA) administers the InstallationMasters® program, which has certified thousands of individuals on industry-accepted installation practices and other critical information related to window installation.
Efficient Window Properties
This mandatory rating measures the amount of heat inside your home that can escape through a window and is the top-left number on all NFRC labels.
- Rating range: 0.10 – 2.00 (this may vary, but is a typical range)
- A lower number means less heat loss
- BUYERS TIP: In cold climates, windows with low U-factors help reduce heating costs
Solar Heat Gain Coefficient (SHGC)
This rating measures the amount of solar heat sun that can enter a home through a window and is the top-right number on all NFRC labels.
- Rating range: 0.00 – 1.00
- A lower number means less heat gain
- BUYERS TIP: In hot climates, windows with a low rating can reduce cooling costs
Visible Transmittance (VT)
This rating measures the amount of solar light that can enter a home through a window. The rating can be found on the middle or bottom row of an NFRC label on the left side.
- Rating range: 0.00 – 1.00
- A higher number means more natural light
- BUYERS TIP: Windows with a high rating may reduce your dependence on artificial lighting and lower monthly utility bills
Air Leakage (AL)
This rating measures the volume of air that can infiltrate a home through a window. This rating can be found on the middle or bottom row of an NFRC label on the right side.
- Rating range: less than or greater than 0.3
- A lower number means less air leakage
- BUYERS TIP: windows rated higher than 0.3 in this specific category disqualify a building from ENERGY STAR certification
Condensation Resistance (CR)
This rating measures a window’s ability to prevent moisture on the interior of the window. This rating can be found on the bottom row of the NFRC label on the left side.
- Rating range: 1 – 100
- A higher rating means less condensation on and around a window
- BUYERS TIP: a higher rating is better but particularly important in cold climates