Replacement Home Windows FAQ
For Muncie & East Central Indiana
Answers To Questions Homeowners Have About Our Windows.
A Crash-Course On Getting The Most Efficient Windows For Your Home.
No question about it: Energy efficiency is one of THE most important aspects to consider when buying replacement windows. This is especially true in the East Central Indiana area, which experiences all kinds of unpredictable weather and fluctuating temperatures.
But how, exactly, do you know if a window is energy efficient? And how can you tell if one window is more efficient than another?
That’s what we explore on this page. Window energy ratings SEEM complicated—but they’re actually simple to understand once you know how the rating system works.
The NFRC Label Tells You All You Need To Know
Everything you want to know about a specific window’s energy efficiency is on the National Fenestration Rating Council (NFRC) sticker. The NFRC is an independent organization that measures window efficiency based on several criteria. Any window that the NFRC has tested will have the organization’s sticker attached to the glass.
Here is what the NFRC sticker looks like:
See those four numbers? Those are ratings for different energy and performance aspects of a window. Windows with sufficient energy ratings are certified by ENERGY STAR®, the government’s official energy-efficiency program.
ENERGY STAR certified windows have the official ENERGY STAR seal on the NFRC label. It looks like this:
Now let’s take a look at each NFRC rating and the requirements for ENERGY STAR certification.
U-Factor
U-Factor rates how well the ENTIRE window insulates. This is measured on a scale from 0 to 1, with LOWER numbers meaning better insulation.
U-Factor is the most important rating when determining how well a window will keep your home warm in the winter. For ENERGY STAR certification in Indiana, a window must have a U-Factor of 0.30 or lower.
Clemens Replacement Windows have a U-Factor as low as 0.23, which is 30% superior to ENERGY STAR requirements.
Solar Heat Gain Coefficient
Solar Heat Gain Coefficient (SHGC) rates the amount of solar heat that penetrates a window’s glass. It’s measured on a scale from 0 to 1. The LOWER the number, the better the glass blocks out the sun’s heat.
SHGC is the most important rating when determining how well a window will keep out excess heat in the summer. ENERGY STAR requirements for SHGC in Indiana vary based on a window’s U-Factor. That said, it’s recommended to go with a window with an SHGC of 0.42 or lower.
Clemens Replacement Windows have an SHGC of 0.20, far exceeding ENERGY STAR’s strictest standards.
Visible Transmittance
Visible Transmittance rates how much actual LIGHT (not solar heat) penetrates the glass of a window. This is measured on a scale from 0 to 1. The HIGHER the number, the more light will pass through the glass.
There is no ENERGY STAR standard for Visible Transmittance. But you’ll want to go with a window that has at least a 0.40 if you want exceptional clarity and natural light. Double-pane windows almost always have better Visible Transmittance ratings than triple-pane windows, which often have a noticeable tint.
Clemens Replacement Windows have a Visible Transmittance rating of 0.47, which allows for clear views of the outdoors.
Air Leakage
Air Leakage rates how much air passes through one square foot of a window. This is measured on a scale from 0 to 1. The LOWER the number, the more airproof the window is.
To be ENERGY STAR certified, windows must have an Air Leakage rating of 0.30 or lower. Anything higher may allow noticeable drafts.
Clemens Replacement Windows have one of the best Air Leakage ratings in the industry: 0.01!
Jennifer S. 