Choosing the Right Windows for Your Climate

If you live in an older home and have decided to change your windows, congratulations are in order! Replacing windows is a great way to better insulate your home during the summer and winter months. The trouble is – windows aren’t a one-size-fits-all purchase. There are different types of glass panes and frames, many of which are designed to work best in certain climates. Rest assured, we have all the details you need so that you can choose the right windows for your home.

Glass Attributes

You may hear the terms U-Factor and SHGC (solar heat gains coefficient) used when describing different glass panes. A window’s U-Factor measures how well the window insulates, while SHGC determines how well the window reflects the sun and reduces glare (which is one way to insulate windows to keep heat out). These measuring tools are important to use to determine what windows will work well depending on your climate.

Understanding the U-Factor

The best windows have a U-factor rating of 0.30 or lower, which means they are extremely energy efficient. When choosing a window replacement, it is important to know if the glass meets or exceeds a specific U-factor rating. If the U-factor rating of the replacement window is lower than your current windows, consider replacing them with another, more energy-efficient option.

High SHGC (Solar Heat Gains Coefficient)

In colder areas, air conditioning may not be a concern, but keeping your home warmer throughout the year may be more important. If you live in a colder region, a window with a high SHGC level may be the best option since the solar heat gained through the window can be used to keep your home at a more comfortable temperature. Therefore, finding a window with an SHGC range of 0.30 to 0.60 can be helpful for insulation.

Energy Performance Testing, Certification, and Labeling

The National Fenestration Rating Council (NFRC) operates a voluntary program that tests, certifies, and labels windows, doors, and skylights based on their energy performance ratings. The NFRC label provides a reliable way to determine a window’s energy properties and compare products. The NFRC label can be found on all ENERGY STAR® qualified window, door, and skylight products. However, ENERGY STAR bases its qualification only on U-factor and solar heat gain coefficient ratings.

Heat Gain and Loss

Windows, doors, and skylights can gain and lose heat through:

• Direct conduction and convection heat transfer through the glass or multi-layer glazing and framing.
• Thermal radiation into and out of a house from room-temperature objects.
• Solar radiation absorbed by building surfaces.
• Air leakage through and around them.

These properties can be measured and rated according to several energy performance characteristics:

• U-factor: Measures how well a window transmits non-solar heat flow. The lower the U-factor, the more energy-efficient the window.
• Solar Heat Gain Coefficient (SHGC): Represents the fraction of solar radiation admitted through a window. A lower SHGC means less solar heat is transmitted; higher SHGC is better for winter heating.
• Air Leakage: Indicates the rate of air movement around a window in specific conditions; lower ratings indicate tighter seals.

Sample NFRC labels show energy efficiency ratings for windows including U-factor, SHGC, visible light transmittance (VT), air leakage (AL), and condensation resistance (CR).

Frame Options

There are many different window frames to choose from, including fiberglass, composite, vinyl, vinyl-clad wood, and aluminum. Here’s how they stack up based on cost, functionality, and performance depending on your region:

• Fiberglass: Fiberglass frames have excellent thermal performance and are sturdy enough to withstand storms and high winds. They resist fading and cracking but are more expensive than vinyl.
• Composite: Composite frames combine materials like aluminum and wood or vinyl and wood, providing good insulation without expanding or contracting with temperature changes.
• Vinyl: Vinyl frames insulate well in summer and winter, require minimal maintenance, and stabilize UV rays. However, fiberglass is stronger.
• Vinyl-Clad: Similar benefits as vinyl but offers a classic look without needing paint.
• Aluminum: While durable and low maintenance, aluminum conducts heat rapidly and is not ideal for extreme temperatures.

Upgrade to Triple Panes

While double-pane windows have many benefits (the air pocket used between the two panes of glass is excellent for insulation), triple-pane windows may also be an option in some parts of the country. Triple-pane windows have three panes of glass and two air pockets, creating greater soundproofing and insulation than double-pane windows provide.

Ideal Climate for Triple Pane Windows

Triple-pane windows are particularly beneficial in climates that experience periods of extreme hot or cold weather for an extended period.

Conclusion

Choosing the right insulating windows for your climate can significantly impact your home’s energy efficiency and comfort. By understanding glass attributes like U-Factor and SHGC as well as selecting appropriate frame materials, you can make informed decisions that suit your specific needs. Investing in quality windows tailored to your climate will not only enhance your living environment but also contribute to long-term energy savings.