Most people only replace their windows once or twice in a lifetime, so it’s important to make informed decisions when it comes time to make the choices needed to get the best windows for your long-term needs.
With the cost of heating and cooling your home rising, getting the best energy-efficient replacement windows for your home. Learn about the basics of window energy-efficiency below.
The Difference between ENERGY STAR Ratings and NFRC Ratings
The ENERGY STAR label informs consumers that a product is energy-efficient, but the NFRC label helps you compare window products by breaking down its energy performance.
Making Sense of the Energy Ratings Found on Replacement Windows
One of the greatest reasons to install replacement windows is to gain the energy efficiency you desire in your home. Save consistently on utilities throughout the year with energy-saving windows. Here are four main ratings (and one optional rating) found on replacement windows:
1. U-Factor
The U-factor measures how well a window will keep interior heat from escaping your home. It calculates heat loss, so it’s a gauge of the window’s effectiveness as an insulator. U-Factor scores range from 0.20 to 1.20 with a lower score meaning the window is better at keeping heat inside your home. The lower the number, the better the product is at keeping heat where it belongs: inside your home. The lower the U-factor, the longer it takes heat to pass through it, and the better it performs as an insulator.
What you’re looking for: Low numbers are best.
2. Solar Heat Gain Coefficient
This is a rating that measures heat gain, or how a window keeps the heat from the outdoors from entering into your home. Its score ranges from 0 to 1, with the lower number meaning less heat will enter your home from the outdoors. The lower the number, the less you’ll need to spend on cooling your home.
What you’re looking for: Low numbers are best.
3. Visibility Transmittance (VT)
The VT rating measures how much natural light will pass through your replacement window’s glass. This rating is contingent on components like low-E coatings, window tints, and colored glass. It measures between 0 and 1. VT has little to do with thermal ratings, but it does impact energy consumption. A higher score depicts the fact that more natural light will be able to pass through your replacement windows. The higher the number, the more natural light you’ll have in your home.
A higher VT rating will decrease the amount of artificial lighting needed in your home, and will therefore impact the amount of energy you need to light your home. A high VT rating doesn’t automatically result in a warmer room. With today’s glazing techniques, it’s now possible to have a very bright room, lit only by the sun—which is just as cool as a dark room in a different location of your home.
What you’re looking for: High numbers are best.
4. Air Leakage
This rating measures how much air will enter your home through your replacement window frames, or around the seal. The air leakage (AL) value ranges from 0.1 to 0.3 with the lower score meaning that your home is more airtight, and more energy-efficient. The lower the number, the fewer drafts you’ll have inside your home.
What you’re looking for: Low numbers are best.
5. Condensation Rating
The NFRC also has a condensation rating that’s optional for manufacturers to include. The higher the number, the better a window resists condensation. Since condensation can hinder views out your window, it’s a great number to be aware of.
What you’re looking for: High numbers are best.
Choosing the Best Window Energy Ratings for Your Home and Climate
When the climate you live in is cold, and you want to heat your home and keep the heat inside, here are the numbers you’re looking for in your energy-efficient replacement windows:
- A high Visible Transmittance (VT) rating will ensure you’ll enjoy lots of natural sunlight in your home.
- A moderate Solar Heat Gain Coefficient value displays that some of the solar heat is allowed into your home.
- A low U-factor indicates heated air stays inside your home, and cold winter air stays outside.
If you live in a hot climate, and you want to let in lots of natural light, and you want to block as much solar heat and heat transmission through your energy-efficient replacement windows as possible, you’ll want:
- A moderate Visible Transmittance (VT) rating
- A low U-factor
- A low Solar Heat Gain Coefficient
As you make decisions on energy-efficient replacement windows, realize that you don’t need the same type of energy-rated windows everywhere in your home. For example, if you have a window that doesn’t get much direct sunlight, the Solar Heat Gain Coefficient won’t be as vital as it is for a window that gets a lot of direct sun.
The Value of Independently Tested Energy-Efficient Windows
The National Fenestration Rating Council (NFRC) offers fair, accurate, credible data on windows. Fenestration comes from the Latin “fenestra,” meaning “opening.” NFRC-certified window products are independently tested, certified, and labeled to help you make the right choice for your home. The NFRC’s commitment to advancing the improvement of windows contributes to making homes more comfortable and more energy-efficient.
A Trustworthy Replacement Windows Contractor
At Kelly Window and Door, we understand how overwhelming it can feel to select replacement windows. That’s why as a replacement windows contractor, we developed a simple process to guide you through the selection of the ultimate window components for your specific needs. We ensure you get the perfect window style for your home, and the best frame material, glass package, and hardware features for your long-term needs.
We stand by the products we offer, and if you have any issues, we fix the problem with no questions asked. Our Quality Assurance Team follows up with you after installation.
Learn more about how replacement windows can transform your home.