Energy-Efficient Windows and Doors: What Are Your Options?

Editor’s note: This post was originally published in June 2018 and has been updated for accuracy and comprehensiveness.

It’s no secret that energy-efficient windows and doors make your house more comfortable. They can also lower your power bill. But making the decision to update your house with new windows and doors is only half the battle. You still have to decide on materials and options!

In this article, you’ll learn:

• The differences between energy-efficient window materials
• Pros and cons of energy-efficient door materials
• What everything on an ENERGY STAR label actually means
• How to recognize an installation job that needs to be redone.

Here are a few key takeaways:

• Double-pane windows are your best bet unless winters get extremely cold where you live.
• A fiberglass front door will give you energy efficiency without compromising on looks.
• Look for windows and doors with the ENERGY STAR label. They’ll help you save money on heating and cooling costs.

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Types of Energy-Efficient Windows

As you shop for windows, pay attention to these three things:

1. The window’s frame material
2. What kind of glass the window has
3. How the window opens and closes

This information will help you compare window options equally.

Window frame

The frame is the material that surrounds and supports the glass. Window frames are available in several different materials. Aluminum, vinyl, fiberglass, and composite are popular in today’s market.

• Aluminum windows are low maintenance but conduct more heat than other options.
• Vinyl windows are easy to find and almost maintenance-free. They can’t be painted if you want a different look in the future.
• Fiberglass windows offer great insulation and won’t expand or contract with temperature changes. They tend to be on the upper end of the cost scale.
• Composite windows combine the energy efficiency and easy care of vinyl and fiberglass with the look of wood. Composite windows can also be stained or painted. Like fiberglass, they’re more expensive than other windows.

Window glass

Single-pane glass is common in older homes. A single pane of glass doesn’t provide much insulation, so it isn’t recommended for replacement windows.

Double-pane glass is the most popular option in replacement windows. It’s the industry standard in new construction. Double-pane windows have argon or krypton gas between the sheets of glass. That gas-filled space serves as insulation. Your house will be quieter and more comfortable with double-pane windows. You’ll also see a reduction in your heating and cooling costs.

Triple-pane glass is less common than double-pane glass. It’s a great option if you winters are really cold where you live. If you don’t have super cold winters, you probably don’t need triple-pane windows. They’re expensive, and recouping your investment may take a long time.

Other options, like glass coatings and tints, can make your windows even more energy efficient.

Low-emissivity glass (also called low-E glass) is window glass with an energy-efficient coating. The very thin glaze blocks UV and infrared rays from the sun without making the room dark.

A low-E coating cannot be applied after a window is installed. If this is a feature you’re interested in, ask your window and door contractor about it before you make a purchase.

Solar control window film filters UV rays and can be applied after a window is installed. Some window films are reflective, but not all are. Talk to a qualified installer to find the best option for your home.

Window operation

How your windows open and close also contributes to their energy efficiency. Think about it this way: A window’s energy efficiency is related to how much air escapes through it. Even with tight seals and gaskets, a window that opens will always release more air than one that does not.

Awning, casement, and hopper-style windows let less air out than single- or double-hung windows. Fixed windows have an airtight seal, but you can’t open them for ventilation.

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Types of Energy-Efficient Doors

Entry doors

Your home’s front door needs to look good and do its part in keeping your house secure. There are so many options on today’s market that you’ll be able to find exactly what you want without compromising on style.

Wood exterior doors are beautiful and classic. They don’t insulate as well as steel and fiberglass doors with foam cores. If you have your heart set on the look of wood, take a look at fiberglass front doors. Fiberglass can be made to mimic almost any material, including wood.

Patio doors

Patio doors are traditionally all glass. This keeps the view to the outdoors nice and open. But since they’re all glass, patio doors aren’t as energy efficient as entry doors.

But that doesn’t mean that energy-efficient patio doors don’t exist! Energy-efficient patio doors will have many of the same features as an energy-efficient window:

• Two panes of glass with insulating argon or krypton gas between them
• Fiberglass, vinyl, or wood frame
• Professional installation to ensure a tight fit

Sliding glass doors offer better energy efficiency than French doors. Keep a close eye on the seals, especially if the door receives a lot of use. The friction from sliding the door open and closed can cause the seals to wear down over the years. Worn seals decrease the door’s efficiency.

You can find energy-efficient French doors, of course. Because both doors open (as opposed to just one in a sliding door), their efficiency rating will be slightly lower than a sliding door. Replace any failing seals on your French doors promptly to reduce air leaks.

How to Read an ENERGY STAR Label

When you buy new windows and doors, keep an eye out for options that carry the ENERGY STAR label. ENERGY STAR products reduce energy costs by an average of 12 percent over their traditional counterparts.

ENERGY STAR is a government program that identifies energy-efficient products for consumers. The ENERGY STAR label ensures that the windows and doors you are buying are truly energy efficient.

When you look at an ENERGY STAR label on a window or door, you’ll see measurements from the National Fenestration Rating Council (NFRC). If those numbers look like gibberish to you at first glance, you’re not alone!

Here’s a quick guide to the terminology you’ll need to know:

U-Factor

The U-factor measures how well a window or door insulates your house. U-factor numbers range from 0.25 to 1.25. A lower number means that a product provides better insulation.

Low-E glass lowers a window’s U-factor. Multiple glass panes and insulating gas between the panes do the same. The U-factor measurement is important no matter where you live. But it’s especially important if you live in a cold climate.

Solar Heat Gain Coefficient (SHGC)

The Solar Heat Gain Coefficient (SHGC) measures how well a window or door blocks the heat from sunlight. SHGC ranges from 0 to 1, but you will typically find numbers between 0.25 and 0.80.

Normally, when looking for the best SHGC, the lower numbers are better. If you live in a colder climate, however, look for a higher SHGC rating. A higher SHGC means the product is better at collecting solar heat to warm your home. For warmer climates, a lower SHGC means the window or door will block heat gain to keep your house cooler.

Visible Transmittance (VT)

Visible transmittance measures the amount of light that comes through your windows. When you add more glazing to your windows, the VT decreases.

VT is measured on a scale of 0 to 1, and you will typically see values from 0.20 to 0.80. If the VT drops below 0.40, everything you see through the window may appear gray. If you want a lot of sunshine to come through your windows, choose a window with a higher VT rating. Consider your options wisely, since unfiltered sunshine can fade furniture, carpet, and flooring.

Air Leakage (AL)

The air leakage rating measures how quickly air escapes through joints or cracks in a window or door. A lower AL number equals less air leakage.

The standard value is 0.3 cfm/ft². The air leakage rating is important because openings in windows and doors can let moisture into the house. That moisture can foster mold growth and cause health issues. Properly sealed windows and doors can also save you money on heating and cooling bills.

Condensation Resistance

Condensation resistance is a measurement of how well a window resists moisture buildup. This feature is measured on a scale of 0 to 100. A higher number means that the window has a high resistance to condensation. This is a good thing, especially in wet or humid climates.

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Proper Window and Door Installation

The best energy-efficient windows and doors are only as good as their installation. Choose your installation company very carefully. Best Pick window and door companies carry general liability insurance, state-required workers’ compensation insurance, and any required trade licenses. They also must meet our high standards for quality of work, cleanliness, and customer service. When you hire a Best Pick, we guarantee that you’ll be pleased with the experience and the end result.

Didn’t use a Best Pick? Keep an eye out for the following signs of a less-than-stellar window or door installation:

• A door that doesn’t hang level in the frame
• Windows or doors that require significant force to open or close
• A door that creaks loudly and consistently
• An increase in your heating and cooling costs

Improper installation can cause all sorts of problems. It can also make your new doors and windows less efficient. Above all, your installer should follow the manufacturer’s installation procedures. If they don’t they’ll void any manufacturer warranties on your windows or doors. That definitely isn’t what you want.

The Bottom Line

Efficient windows and doors are essential to making your house comfortable and affordable. There are so many products to choose from on today’s market. It can be overwhelming at first, but a window and door replacement expert can help narrow your options.

• Carefully consider your climate, your budget, and the market value of your home to settle on the best products for you.
• Opt for ENERGY STAR windows and doors when they’re available.
• Pay attention to the NFRC ratings. That information will help you compare each product’s efficiency features.

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