What is Energy Star version 7?

Recently, the U.S. Environmental Protection Agency’s (EPA) ENERGY STAR® program released its final version 7 specification for Residential Windows, Doors, and Skylights that establish higher energy-efficiency benchmarks for products to earn EPA’s coveted ENERGY STAR certification. This new specification outlines more demanding certification criteria of various fenestration products.

The energy performance of windows is essential to overall building efficiency and its environmental impact. More efficient windows will reduce your home’s carbon emissions on day one, independent of what source of energy is used to heat and cool your building. Although windows only account for about 10% of an average home’s surface area, approximately 35% to 45% of the heat homes lose in winter months pass through windows. More insulative windows, like the industry-leading models that the new ENERGY STAR criteria will certify, can bring those losses down considerably, which saves energy and money.

Do Westlake Royal Window Solutions products meet Energy Star version 7 requirements?

Yes! We have several Energy Star certified window and sliding glass door products available including standard, impact and STC (Sound Transmission Class) grades. These support the Southern, South-Central and North-Central climate zones and are available from all four of our manufacturing plants:

Magnolia collection (Baldwin, GA)
Krestmark collection (Dallas, TX)
Legacy collection (Houston, TX)

When do Energy Star version 7 certification requirements go into effect?

Energy Star version 7 certification requirements go into effect October 23, 2023. All fenestration products bearing the Energy Star label must adhere to the new requirements.

Are Energy Star version 7 certified windows mandatory?

Energy Star version 7 certified windows are not mandatory. However, some builders and zoning districts may require installation of Energy Star certified windows. Additionally, homeowners may choose Energy Star certified windows for energy savings as well as potential tax credits.

If you require an Energy Star rated product for your project, it is very important to select the proper performing glass option for the location in which it will be installed. Use the Energy Star Climate Zone Finder to determine your climate zone.

The NFRC label lists important fenestration performance ratings and can be found on all of Westlake Royal Windows’ products. Our label lists the performance ratings in four main categories: U-Factor, Solar Heat Gain Coefficient (SHGC), Visible Transmittance (VT) and Air Leakage.

Condensation (outdoor and indoor surfaces)

Condensation is water droplet build up on one of the glass surfaces. Today’s high performance LoE coatings are more susceptible to condensation due to their high insulating characteristics. It is important to understand where condensation occurs to determine if you have a problem or not. Condensation within the airspace of the window indicates a crack in the glass or failed seal and replacement should be considered. Condensation on the indoor or outdoor panes are usually indicative of a temporary environmental factor and should not be replaced.

Indoor Condensation or Glass Sweating on the Room Side Glass Surface – glass having indoor condensation or sweating caused by high room side humidity conditions should not be replaced. This phenomenon is usually seen in the winter at the bottom edge of the glass, around the glass periphery, or sometimes on the complete indoor glass surface. It is caused by high room side humidity conditions when the indoor glass temperature is below the dew point of the room side air. Common examples of indoor condensation:

  • Winter – boiling food on a stove within a pot of water, can cause nearby windows to sweat
  • Summer – using air conditioning on a cooler morning, can cause nearby windows to sweat

Outdoor Condensation and Frost Glass units – condensation or frost on the outdoor glass surface of an insulating unit is not an indication that the glass or insulating unit is defective and should not be replaced. Under the right set of atmospheric conditions, it is possible to get condensation or frost on the outdoor surface of an insulating glass unit. Specifically, these conditions are as follows:

  • Glass temperature below the dew point
  • Clear night sky
  • Still air
  • High relative humidity
  • Highly insulating IG units potentially using:
    •  High performing Low E coatings
    • Multiple airspaces
    • Multiple Low E coatings

For additional information:
Cardinal Glass – Outdoor Condensation
Cardinal Glass Technical Bulletin – Insulating Glass Condensation

Window Tint Film

Use caution when applying a tint film to your window or sliding glass door. While it will provide a SHGC boost, application will void the warranty as it disrupts the insulated glass engineering it was originally tested and certified to.

Acid Washing

Use caution when using acid washing products when cleaning masonry to ensure they do not come in contact with windows and sliding glass doors. Many of these products are too harsh, which can etch the glass, compromise the insulated glass airspace seal, disrupt proper operation of sashes and cause brittleness/discoloration/damage to the PVC glazing bead/frame components. Windows and Sliding Glass Doors which have come into contact with acid wash products are not covered under warranty.


Windows that are field mulled by the customer must be attached/sealed in a specific manner and adhere to certain maximum size requirements or the warranty of the individual windows is void. If you don’t see Field Mulling Instructions on our website for the particular series you are installing, please contact your Sales Representative or Customer Service Representative for guidance.

NFRC Ratings & Energy Star Compliance


200/220/275 Series
250 Series
400 Series


250 Series
700 Series
900 Series


400/4000 Series
5957 Series