New windows can be pretty expensive, especially if you’re replacing multiple at once or opting for energy-efficient materials. But did you know that the right windows can actually save you money in the long run?
This article discusses everything you need to know about upgrading your windows and answers common questions like how much energy new windows can save and the different ratings to look for when buying a new one.
Why Windows Matter: Heat Loss Through Windows
Windows are one of the primary pathways for energy to escape from a building, especially during colder months.
According to a study published by Penn State College of Earth and Mineral Sciences, about 18% of a building’s total heat loss occurs through its windows. This means that nearly one-fifth of the energy used to heat a home or office can be lost directly through window areas, even though they make up only about 15 to 20% of a building’s wall surface area.
As such, improving a window’s efficiency ratings is one of the most effective ways to cut down on long-term energy costs and reduce your monthly utility bills.
On average, energy-efficient windows can reduce your energy bills from 7% to 30% annually, or $126 to $465 a year, per the US Department of Energy.
Understanding Energy Efficiency Ratings
When shopping for new windows, look beyond appearances. Some may look sleek and modern but offer poor thermal performance, while others have high energy ratings but are made of weak materials.
First, let’s discuss the various energy efficiency ratings you may encounter when buying windows:
U-Factor Windows
U-factor, also known as thermal transmittance, measures how easily heat escapes your windows and doors. U-factor values range from about 0.20 (very efficient triple-pane windows) to 1.20 (single-pane windows). The lower the U-factor, the better the insulation.
You can manually calculate a window’s U-factor using the formula for heat transfer (Q = mcΔT), but this is rarely necessary because reputable window manufacturers list the window’s U-factor rating on the National Fenestration Rating Council (NFRC) sticker.
If the window doesn’t have an NFRC sticker, consider another manufacturer, as their windows may not have been independently tested or certified for energy performance.
Solar Heat Gain Coefficient (SHGC)
Solar Heat Gain Coefficient (SHGC) measures how much solar heat enters through your windows, ranging from 0 to 1.
Unlike U-factor, which should be as low as possible to minimize heat loss, a window’s ideal SHGC value depends on your area’s climate.
Lower SHGC ratings (below 0.30) block more solar heat and are therefore suitable for hot climates, while higher SHGC ratings (0.40 to 0.85) let in more warmth and are best for colder areas.
If you live in an area that has both hot and cold seasons, we recommend getting a balanced SHGC value of 0.40 to 0.60.
Insulation by R-Value
R-value measures how well a material resists heat flow. R-value ratings for windows range from R-1.5 to R-7, with higher values equaling better insulation and reduced heat transfer.
Standard ENERGY STAR insulated glass windows have an R-value of around 3, but you should look for windows with higher R-values when possible to maximize energy efficiency.
Types of Energy-Efficient Windows
Today’s market offers a wide selection of energy-efficient windows to suit virtually every climate, style, and budget. Here are some of the most common:
Double Pane Windows – Basic Standard Today
Double-pane windows are considered the standard for most modern homes. They offer a good balance of durability, energy efficiency, and affordability, making them a practical and cost-effective choice for most homeowners.
Double-pane windows are made of two sheets of glass separated by a spacer and an insulating air or gas-filled gap, typically about 12mm wide. The gap acts as a thermal barrier, doubling insulation compared to single-pane windows.
That said, it offers less insulation and noise reduction compared to triple-pane windows, especially in extreme climates and noisy environments.
Triple Pane Windows – Superior Insulation for Extreme Climates
If you live in areas that experience extreme heat and extreme cold, investing in triple-pane windows is the smart choice.
As the name suggests, triple-pane windows consist of three panes of glass with two air spaces in between. They offer better insulation, reduced drafts, and noise reduction by up to 50% when compared to double-pane windows. They’re also more durable and secure than double-pane windows due to the additional layer of glass.
With that said, triple-pane windows cost 10% to 15% more than double-pane windows. That doesn’t seem like a huge difference at first, but costs can add up quickly, especially when you’re replacing multiple windows.
Still, triple-pane windows often pay for themselves over time through lower energy bills. The added insulation helps maintain a more consistent indoor temperature, which is particularly beneficial for areas with extreme weather.
Low E Coatings – Reflect Infrared Light, Improving Insulation
Low-E Coatings are microscopic, transparent metallic layers applied to the surface of window glass. These coatings reflect infrared heat while allowing visible light to pass through, helping keep heat inside during winter and outside during summer.
Most energy-efficient double- or triple-pane windows feature Low-E coatings, baked onto the glass surface during the manufacturing process.
Gas Fills – Argon vs. Krypton for Extra Insulation
The space between double or triple-pane windows is filled with one of two gases: argon or krypton.
Both gas fills have distinct advantages and disadvantages. Argon is the most common gas fill; it’s inexpensive and provides good insulation.
Krypton, however, is the superior gas fill. It offers better insulation than argon, which is beneficial for narrow windows and areas that experience extreme climates. It’s more expensive than Argon, though, with some costing three and sometimes even five times the amount of Argon.
Window Framing Materials – Vinyl, Fiberglass, Wood-Clad
A window’s frame material also plays a big role in a window’s thermal performance. Among the most common window framing materials you’ll find are vinyl, fiberglass, and wood-clad.
Vinyl frames are cost-effective, moisture-resistant, and can be insulated internally.
Fiberglass, on the other hand, excels in durability. They’re resistant to warping and rot, and have up to 40% longer lifespans than vinyl. It isn’t uncommon for fiberglass frames to last 50 years or more, compared to vinyl lasting only around 20 years.
Wood-clad frames combine the natural insulation of wood with protective exterior cladding (aluminum, vinyl, or fiberglass), making them both aesthetically pleasing and energy efficient.
The lifespan of wood-clad windows depends on the quality of the wood and the durability of the protective exterior cladding. This means that wood-clad frames made with fiberglass cladding last longer than wood-clad frames with vinyl or aluminum cladding.
Best Energy Efficient Windows in 2025
Here’s a look at some of the best energy-efficient windows in 2025:
Fiberglass Windows With Double- or Triple Glazing
Fiberglass frames are known for their longevity. Combine that with double- or triple-glazed windows and you have a durable, energy-efficient window that works exceptionally well in almost any climate.
The choice between double and triple glazing depends on where you live.
If you live in an area with a mild or temperate climate, like San Diego or coastal regions of Oregon and Washington, double-glass panes will get the job done.
But if you live in, say, California, Kansas, or Minnesota, investing in triple-pane windows is a smart move.
Vinyl Frames with Double Low-E Coatings
Let’s say you live in an area with an extreme climate but want to save money or don’t have the budget for triple glazing or fiberglass frames.
In that case, the next best thing to get is vinyl frames with double Low-E coatings on double-pane windows. These windows will save you several hundred bucks and still provide solid insulation year-round. And though not as durable as fiberglass, vinyl frames are still a solid pick because they balance performance and cost.
Hybrid Wood-Clad Windows
If you love the aesthetic of wood, look for a wood-clad window made with vinyl or fiberglass. Both options are good, with fiberglass racking extra points for durability.
Ideally, you want the wooden frames to be made of rot-resistant hardwoods like oak, mahogany, and teak, or softwoods like Western red cedar or Douglas fir.
Avoid pressure-treated wood because it’s susceptible to warping and rotting when exposed to the elements.
Smart Window Systems
If money isn’t a concern, consider investing in smart glass windows. Also known as dynamic windows or switchable windows, smart window systems can adjust tint in real-time. They automatically darken when intense sunlight hits, reducing thermal gain and glare.
Smart windows, on average, can cost between $100 and $200 per square foot, compared to regular windows that cost between $25 and $40 per square foot.
How Much Can New Windows Save on Energy?
Replacing old single-paned windows with efficient, double- or triple-paned windows can reduce your electricity bill from 7% to 20% annually. The higher the energy efficiency, the higher your savings. Ideally, you want windows with a low U-Factor, an appropriate SHGC for your climate, and a high R-Value.
Do New Windows Save Money? Cost vs. Long-Term Savings
Installing new windows can be expensive, with high-performance options like triple-pane glass or fiberglass frames costing upwards of $3,000 excluding installation.
However, windows typically pay for themselves within 5 to 15 years through energy savings. Well-insulated windows can reduce energy loss by up to 20%, which translates into lower utility bills year after year.
Other Benefits of New Windows
Outside energy savings, new windows offer:
Increased Comfort
With new windows, you no longer have to worry about cold drafts or hot spots near your windows. Energy-efficient windows keep your home cozy in winter and cool in summer.
Reduced Noise
Double- and triple-pane windows offer excellent sound insulation. The extra layers of glass and insulating gas create a barrier that reduces outside noise, making your space quieter and more peaceful.
Boosted Home Value
Given how expensive window replacements can be, energy-efficient windows attract more potential buyers. They add to the aesthetic of the house and lower energy costs, increasing your home’s resale value.
FAQs
Are double-pane windows enough to reduce heat loss?
Double-pane windows reduce heat loss by 40 to 50% compared to single-pane windows. However, that might not be enough if you’re living in an area that experiences extremely cold weather. In such cases, triple-pane windows are the better choice.
What is the best type of window for hot climates?
For hot climates, choose windows with a low SHGC to block heat from the sun, ideally 0.25 or less. Look for double- or triple-pane windows with Low-E coatings, gas fills, and vinyl or fiberglass frames to maximize energy efficiency and reduce cooling costs.
How does Argon gas in Windows work?
Argon gas is placed between the glass panes to improve insulation. It’s thicker than air, so it slows down heat from passing through the window.
What’s the difference between U-factor and R-value?
U-Factor and R-Factor both measure a window’s insulation, but in opposite ways. U-Factor shows how much heat escapes, so lower ratings are better. On the other hand, R-value shows how well a window resists heat flow. This means that the higher the R-value, the better.
What’s the difference between U-factor and R-value?
Triple-pane windows cost 10% to 15% more than double-pane windows. Whether they’re worth the cost depends on where you live.
In mild climates, double-pane windows are more than enough. In very cold or hot climates, triple-pane windows are worth the investment.
The same is said if you live in an area with lots of noise pollution; triple-pane windows reduce noise by up to 51dB compared to double-pane windows at 35dB.
How Long Do Energy-Efficient Windows Last?
Depending on the frame and glass quality, energy-efficient windows can last anywhere from 15 to 50 years or more. Regular maintenance can significantly extend the life of your windows.
How much does professional window installation cost?
Professional installation can cost between $300 and $2,500 per window, depending on the location, installation complexity, and window size.
Need Expert Help With Window Replacement?
Upgrading your windows can be a big investment, but it pays off in comfort and savings. For professional advice, quality products, and expert installation, Kobyco is your trusted local expert. Whether you’re considering double- or triple-pane windows, energy-efficient coatings, or durable frames, their team can help you choose the right windows for your home and climate and install them perfectly to maximize energy savings. Contact Kobyco today to get started!