Looking for energy-efficient windows for your home? Replacing older windows with newer, more efficient windows can be a great way to save money on your monthly electricity bills, but not all “energy efficient” windows are made equal.
There’s a lot to consider when shopping for windows that can help you reduce your energy bills. Let’s go over what you should know before buying any window that’s marketed as being energy efficient:
Energy Efficient Windows and ENERGY STAR
When shopping for an energy efficient window, the first thing you’ll probably want to see is if the window is ENERGY STAR v7.0 program compliant.
ENERGY STAR is a program that was developed by the United States Department of Energy (DOE) and the U.S. Environmental Protection Agency (EPA). It covers all kinds of household products, including windows, doors, and skylights.
The stated goal of the program and its blue label is to provide “simple, credible, and unbiased information that consumers and businesses rely on to make well-informed decisions” in regards to energy efficiency (Source: ENERGY STAR’s About page).
ENERGY STAR provides energy efficiency criteria for windows and doors to meet in order to be certified as energy efficient under the program—earning the coveted blue label proving the product’s energy efficiency. Windows that meet ENERGY STAR’s requirements can qualify for tax rebates and other incentives.
The program assesses windows primarily on two criteria: U-Factor and Solar Heat Gain Coefficient (SHGC).
- U-Factor. A measure of how well the window insulates the home from outside temperatures. The smaller the number, the less heat moves between the structure and the outside. Typically measured on a scale between 0.2 (Best) and 1.2 (Worst) according to the National Fenestration Rating Council (NFRC).
- Solar Heat Gain Coefficient (SHGC). A measure of how much warmth from the sun penetrates the window in the form of ultraviolet and infrared radiation. The lower the number, the less heat gets in from sunlight. The NFRC measures this on a scale from 0 (strongest protection) to 1 (weakest protection).
Air leakage, another important window energy efficiency factor measured by the NFRC, strongly correlates with the window’s overall U-factor. This is because if air can move through the shut window easily, the window will not do as good of a job of preventing thermal transfer.
Do ENERGY STAR Requirements Change?
ENERGY STAR program requirements do periodically change. The latest version of the program is v7.0.
Additionally, program requirements for windows and doors may also differ based on where you live and whether you’re looking for basic compliance or want to qualify for tax incentives.
Here in Florida, windows need to have a u-factor of 0.32 or less and an SHGC of 0.23 or less to be considered compliant. To qualify for tax rebates, they would need to have a u-factor of 0.21 or less and an SHGC of 0.23 or less.
Meanwhile, in Juneau, Alaska, a program-compliant window would need to have a U factor of 0.22 or less and an SHGC of more than 0.17 to meet prescriptive requirements.
The difference in focus is because of the different climates. In Florida, you want to keep the heat out for most of the year, so lower SHGC is better than higher. Meanwhile, in Alaska, you’d want more warmth, so higher SHGC values are considered optimal there.
So, when you’re shopping for energy efficient windows, it’s important to ensure that the windows you choose are ENERGY STAR certified for Southern climate zones, specifically.
What’s the NFRC?
The National Fenestration Rating Council, or NFRC, is an organization that certifies the performance of “fenestration” (i.e., windows and doors). The NFRC creates certification labels that spell out the performance characteristics of windows and doors to make it easier for consumers to know if a window or door meets energy standards for their home.
The NFRC Label shows information about a window’s U-factor, SHGC, visible transmittance, condensation resistance, and air leakage ratings.
What’s Visible Transmittance?
Visible transmittance, or VT, is a measurement of how much pure light can pass through a window. The higher the number, the more light the window lets in. So, a window with 0 VT would be completely opaque while a window with 1 VT would let in 100% of all visible light.
How Can I Identify an Energy-Efficient Window?
The NFRC label is one of the easiest ways to identify an energy-efficient window while you’re shopping… but how do you verify that the windows in your home meet current efficiency standards?
While not foolproof, there are a few features that are common to energy-efficient windows that you can use to identify them in your home:
- Frame Material. Is the frame of the window made of metal, wood, or plastic/vinyl? Metal windows are tough, but tend to transmit much more heat than vinyl or wood. So, if the frame is made of metal, it likely isn’t an energy efficient window.
- Multiple Panes of Glass. How many panes of glass does the window’s sashes have? Is it a single pane of thick glass or multiple panes of glass? Windows with multiple panes of glass separated by air gaps tend to be more efficient than ones with a single thick layer of glass.
- Butyl or Other Sealant. Some windows with multiple panes of glass might have butyl or other sealants in them at the edges of the glass panes to block air leakage. If the butyl has signs of tiny pinholes, evenly spaced, the window may even have been given an inert gas fill (such as argon gas) to further enhance its insulating properties.
A tinted window could be a sign of an energy-efficient window, but not all tints actually improve energy efficiency. Some tints are purely decorative or only work to block visible light rather than the infrared and ultraviolet radiation of the sun that actually heats up your home.
One way to check if a window’s tint improves energy efficiency is to stand in the sunlight coming through it and feel if your skin warms up or not. If you can immediately feel warmth, odds are that it’s just a decorative tint rather than a low-e glass coating.
Benefits of Energy-Efficient Windows
So, why get windows with strong energy efficiency features? There are a lot of reasons to go with windows that are more efficient in Florida, such as:
- Saving Money on Cooling Your Home. Because energy efficient windows prevent thermal transfer between your home and the outside, your air conditioning system doesn’t have to consume as much energy keeping your home at a comfortable temperature. This helps to reduce your monthly electricity bill, saving you money.
- Improved Comfort Year-Round. Preventing excessive temperature changes in your home helps keep it more comfortable year-round, day or night.
- Protecting Your Home’s Furniture. Low-e glass windows that have solar control films that block ultraviolet light can help protect your furniture from fading due to excessive exposure to sunlight.
- Tax Incentives. ENERGY STAR compliant windows can qualify your home for tax rebates and other incentives that help reduce your tax burden.
- Improved Home Value. Having new energy efficient windows can improve your home’s curb appeal and resale value in the future, should you decide to resell it in the future.
Need Energy Efficient Windows?
When it comes to energy efficient windows, installation quality can make or break your windows. The better the installation, the more efficient your windows will be. Meanwhile, substandard installation can compromise even the most efficient windows.
That’s why it’s important to ensure that your windows are installed properly by a real team of experts, not random subcontractors who don’t know what they’re doing or are intentionally cutting corners to save time and money.
Real experts know to use the right tools and techniques to put in windows and ensure a tight seal around the opening that eliminates air gaps which let warmth into and out of your home.
We never subcontract our work to third parties. That way, we can guarantee the consistency of the windows we install. We’re so confident in the quality of our windows and our installation work that we provide a 25-year labor warranty and a 50-year material warranty!
Reach out to Karoly Windows & Doors to get energy efficient windows installed by a team of experts! Our in-house installation pros know how to help homeowners get the most out of their windows’ energy efficiency, so you can save more and rest easy knowing you’ve gotten the best windows with the best installation service in Tampa Bay!
