Find a Dealer in Your AreaSUMMARY: In this article, you’ll learn what the four biggest window energy ratings numbers mean. While these are the most important energy numbers there are other reasons to choose a particular window over another. The National Fenestration Rating Council (NFRC) tests windows and doors and publishes test results which end up on the NFRC Labels on each new window.
Window Energy Ratings Definitions
U-Factor: This is your insulating property of the window. The window’s ability to keep out the cold.
SHGC: This (Solar Heat Gain Coefficient) rating is the window’s ability to block out the heat from the sun. You want your windows to reflect, not absorb, heat.
Visible Transmission: The VT rating is the amount of light that the windows will allow into your home. A clear window would have a rating of 1 since it does nothing to block sunlight.
Air Leakage: How well is the window constructed? The frame, weatherstripping, rails, etc. How well do they work in preventing air leakage.
Why Are We Named “Experts”?
What is an expert anyway? It’s a person or organization who possesses comprehensive and authoritative knowledge on a subject. We are experts in our field by a combination of training and experience. Training by both the manufacturers and other industry trade sources. We don’t take our name lightly.
Take products for example. We have almost 2 dozen manufacturers we have elected to supply to our customers based on quality, performance, reliability, and warranty coverage.
When you contact us and deal with our people you’ll quickly experience the kind of respect and dignity that is often rare in the home improvements industry. We have selected the best employees and trained them to offer only 5 star level service.
When we install windows or doors, we follow strict and proven processes in order to arrive at consistently the best outcome: A Lifetime Leak-Free Guarantee.
U-Factor Explained – Window Energy Ratings
The window U-factor quantifies how well a window insulates, specifically its rate of heat loss or gain. A lower U-factor signifies superior insulation. For homeowners, selecting windows with the appropriate U-factor for their climate translates directly into tangible benefits: reduced energy consumption for heating and cooling, lower utility bills, enhanced indoor comfort through minimized drafts and temperature fluctuations, and a smaller carbon footprint due to decreased energy demands.
SHGC Defined – Window Energy Ratings
The Solar Heat Gain Coefficient (SHGC) measures how much solar radiation a window allows to pass into your home, expressed as a number between 0 and 1. A lower SHGC means less solar heat enters, which is ideal for hot climates to reduce cooling loads and lower air conditioning bills. Conversely, a higher SHGC allows more solar heat, beneficial in colder climates for passive solar heating and reduced reliance on furnaces, leading to year-round comfort and significant energy savings.
Visible Transmission or VT – Window Energy Ratings
The Visible Transmittance (VT) rating indicates how much visible light passes through a window, ranging from 0 to 1. A higher VT means more natural light illuminates your home, reducing the need for artificial lighting and lowering electricity bills. Choosing the right VT ensures optimal daylighting, enhancing comfort and mood by creating bright, welcoming spaces. It’s a balance: too high might cause glare in sunny rooms, while too low can make rooms feel dim, impacting both aesthetics and energy use.
Air Leakage Rating – Efficiency Of The “Non-Glass” Components Performance
The Air Leakage (AL) rating quantifies how much air passes through a window’s sealed components, measured in cubic feet per minute per square foot (cfm/ft²). A lower AL rating, ideally below 0.3, indicates a tighter seal and less unwanted air infiltration. For homeowners, this means significant benefits: fewer drafts, more consistent indoor temperatures, reduced energy waste from heating and cooling, lower utility bills, improved indoor air quality by keeping out dust and allergens, and a quieter home by minimizing outside noise. This is completely independent of the glass package (IGU) performance rating.
What Happens At The Window Experts In-Home Consultation?
There are many factors we will consider when we visit your home. We want to help you make the best decision based on a number of initial inputs.
- Your Home’s Orientation: Which way does your home face? We may choose a different specification base on whether the walls face North, East, West or South.
- Amount Of Shade: How much of your home is shaded by trees? This may affect the SHGC we recommend as well as the VT rating.
- Your Home’s Age And Construction: How and when your home was built may influence the window manufacturer and window frame types to select from.
- Neighborhood/Community Noise Level: In noisier communities (near freeways, airports, and downtown) we may recommend a specific glass package with asymmetric glass or with laminated glass to reduce noise levels.
- Your Budget And Desired Appearance: We have so many choices from vinyl to wood to fiberglass – all with unique characteristics and colors available.
- Opening Style: Certain window styles go best with different home architectures.
The Value Of Choosing The Window Experts
Above are all the value you get out of working with us. You get stellar customer service and expert knowledge of our manufacturing partners and which windows would work best in your home. Our consultations are free and without obligation. Start your Estimate today by completing a request form. Or call us directly.
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