Best Energy Efficient Windows For Your Home

Energy Efficient Windows Summary:

• Learn the importance of the NFRC label
• Find out more about Low-E coatings
• Dive deep into window technology
• Discover the average energy savings

It’s not breaking news that homeowners are watching their energy bills. Unfortunately, most people are watching them go up! Where does all that heating and cooling money go? Why isn’t your home consistently comfortable? Can Energy Efficient Windows help?

There are many individual upgrades you can do to your home to reduce energy use. Energy Efficient Windows are one of the best methods with the biggest impact. The reason is in heat gain from the sun and air leakage causing your air conditioner to work overtime due to windows and doors that do not seal properly.

There has to be a way to reflect the sun’s energy away from your home. The answer is in the low emissivity coatings on the glass. Low-e in the invisible metal oxide coatings that cause the UV rays from the sun to bounce off your windows before they get the chance to heat up your home.

As far as keeping your heated or cooled air inside your home, the answer is the U-Factor rating. This rating is an insulation indicator similar to saying R-9 when speaking of fiberglass bat insulation.

There are a number of tools used to measure the energy efficiency of your windows. You can check for air leakage at home using a candle close to your window. Is the flame steady or does it flicker or lean towards the window or away from the window?

A flame from a match or a lighter can also be used to check for the existence of low-e coatings. When a lit match or lighter is held near the glass, reflections of the flame will be visible. If the window has a Low-E coating, one of the reflections will have a slightly different color or hue than the others, often appearing slightly bluish or greenish. 

Besides the DIY self tests, the National Fenestration Rating Council (NFRC) performs tests on windows and doors and displays the results on the NFRC Label. When your new windows arrive or if you shop for windows in our showroom, you’ll be able to compare NFRC labels from various manufacturers.

Energy Efficient Windows: What Are The Numbers?

Two of the numbers on the NFRC label are the most important numbers to understand and compare.

SHGC: The Solar Heat Gain Coefficient (SHGC) rating for replacement windows measures how well a window blocks heat from the sun. It’s expressed as a number between 0 and 1, where a lower number indicates less solar heat passes through the window and into your home. For Texas homes, it’s generally recommended to look for replacement windows with a low SHGC rating, ideally 0.30 or lower, to minimize solar heat gain during the hot Texas summers. This will help keep your home cooler and potentially reduce air conditioning costs. Consider a SHGC of 0.25 or lower if your windows receive a lot of direct sunlight.

U-Factor: The U-factor of a residential window measures how well the window insulates, indicating the rate of heat flow through the entire window assembly (glass, frame, and spacers). A lower U-factor signifies better insulation, meaning less heat will transfer through the window. For Texas homes, especially in the hot climate zones, it is recommended to choose replacement windows with a low U-factor to minimize heat gain during the summer and heat loss during the cooler months. Aim for a U-factor of 0.30 or lower to maximize energy efficiency and comfort in your Texas home. Some energy-efficient windows, particularly those with double or triple panes, low-E coatings, and gas fills, can achieve even lower U-factors, further enhancing insulation.

Visible Transmission: The Visible Transmission (VT) rating of residential windows indicates how much visible light passes through the glass.It’s expressed as a number between 0 and 1, where a higher number signifies that more daylight enters the room. For example, a VT of 0.60 means that 60% of the visible light is transmitted through the window. While a higher VT can brighten interiors and reduce the need for artificial lighting, it’s important to consider the balance with other factors like the Solar Heat Gain Coefficient (SHGC), especially in warm climates like Texas. Windows with high VT might allow more solar heat, potentially increasing cooling costs. Therefore, when selecting windows for Texas homes, consider your desired level of natural light while also aiming for a lower SHGC to manage heat gain effectively.

Air Leakage: The Air Leakage (AL) rating of a residential window measures the amount of air that passes through the window’s frame and operable sections (like where the sash meets the frame) in cubic feet per minute per linear foot of crack around the window. This rating is expressed as a number, and crucially, a lower AL number indicates a tighter window with less air infiltration. Reducing air leakage is vital for energy efficiency as it prevents drafts, minimizes heat loss in winter and heat gain in summer, and can contribute to a more comfortable and consistent indoor temperature. When selecting residential windows, particularly for energy-conscious homes, prioritize windows with a low Air Leakage rating.

Bottom Line: What Numbers For Energy Efficient Windows In Texas?

As a resident of Texas, you are quite familiar with the seasons we get here. There are many more months of running your air conditioner than months running your heater. As such, the most important number for Texas windows is the SHGC. Remember, the number goes from Zero (allowing no solar energy gain) to One (affording no solar heat blockage at all) so you’ll look for the lowest SHGC number possible. A SHGC of .25 is usually the most popular rating for our Texas windows.

Opposed to the SHGC number is the U-Factor number. When the SHGC goes lower, the U-Factor rating trends higher. So a .30 is just fine all around Texas.

You probably want as much natural light in your home as possible, right? The Window Experts offers a variety of windows from multiple brands…about 20 at last count. Most of our tried, trusted, and recommended windows use glass from Cardinal Glass. Cardinal is a popular glass manufacturer and offers the perfect residential glass for Texas energy efficient windows. It’s call Low-E366. With 3 coats of solar energy reflecting low-e coatings, the visible transmission rating of this glass is 66%, meaning 66% of the natural light will still enter your home. In other words, it does not significantly darken your home.

How Much Can The Average Homeowner Save On Energy?

Making your home more efficient by installing all energy efficient windows and doors can result in savings exceeding 35% when investing in the full package of, for example, fiberglass framed windows with dual-pane Cardinal Lo-E366 glass and argon gas filled. Compare to the less expensive big box store windows with basic Energy Star ratings where you’ll realize lower savings of up to 15%.

How Can I Get Help Selecting The Best Windows For My Home?

Ask the Experts…The Window Experts. We pride ourselves for offering the best selection of windows available. We have evaluated, installed, and vetted from the best of the best. Schedule a visit from one of our low-pressure window consultants if you’re ready to find out which windows work best for your home and your budget.