How Do Energy Efficient Windows Work?

When it comes to the features of your home, aesthetics are important. However, there’s another essential consideration that you should keep in mind: energy efficiency. And when it comes to choosing energy efficient windows, you can save on your heating and cooling expenses, giving you a better return on investment.

Rising Costs of Living

The mounting costs of living are always going to be a cause for concern for many homeowners. However, investing in energy-efficient features such as home windows is a good long-term saving plan.

Homes need energy efficient windows for energy conservation.

When it comes to home renovations and upgrades for windows, most people would think it’s all about selecting new paint colors, choosing new blinds, or updating window treatments.

Most of us don’t usually think about how much the windows affect our residence’s energy consumption, utility bills, and overall property value.

One fantastic way to manage electricity consumption (and reduce energy waste) is to replace your old and outdated home windows to energy-efficient options available on the market today.

Energy Efficiency Is Vital

Old and outdated windows are likely to let air escape through their cracks. Also, windows with inefficient parts or that are not properly installed also tend to let the air out.

Because of this ineptitude, the heating and cooling system in your home will have to work harder to sustain a comfortable indoor temperature.

Energy efficient windows are the solution to this problem. When you choose products with excellent energy efficiency, you are getting the following benefits:

Enhanced Comfort

Reducing the air escaping from inside the house keeps your space more comfortable. There’s less drafts and less noise pollution.

Reduced Energy Bills

Windows without energy efficiency abilities are one of the reasons why property owners have high energy costs. When you install energy efficient windows in your home, you help your heating and cooling system, thus you also save on money.

For a typical home, replacing old windows with an ENERGY STAR rating can help save up between $100 and $500 per year.

Lessened Carbon Footprint

Innovative materials, expert installation, and fantastic craftsmanship help alleviate the impact of your house on the environment. Choosing good-quality and energy efficient windows can save on carbon dioxide production of a home.

Energy Efficient Windows: Performance Factors

Before you choose the best type of replacement windows for your house, it’s important to know how energy efficiency is measured.

There are categories in measuring the performance of energy efficient windows.

There are many factors that determine the improvement of comfort and thermal performance in your home when you switch to energy efficient items. Figuring out what those factors mean to general energy efficiency will help you choose the home windows you need.

The National Fenestration Rating Council (NFRC) is an organization overseeing the independent testing, certification, and verification of energy efficient doors, windows, and skylights.

The NFRC helps property owners compare the energy performance of skylights, doors, and windows. Their testing does not necessarily determine a good or bad score. Instead, they distinguish what the product’s energy performance levels are.

This is where the ENERGY STAR program from the US Department of Energy comes in. The ENERGY STAR rating helps consumers identify products rated by the NFRC with the best energy performance levels.

Performance Gradings

The NFRC tests all ENERGY STAR certified doors, windows, and skylights. They determine the performance grade in five categories:

U-Factor or U-Value

This measures the rate of heat lost during a window’s installation. When the U-Factor is lower, you get better insulation through your home windows. You also get a better resistance when it comes to heat flow.

The best efficiency windows (triple-pane windows) can get a U-Factor/U-Value of 0.15. Some double-pane, energy efficient windows have a U-Value of 0.30.

Solar Heat Gain Coefficient

The Solar Heat Gain Coefficient (SHGC) calculates the solar energy conducted by the home windows. This measurement shows the windows’ performance when it comes to blocking heat coming from the sun. The typical SHGC range sits between 0.25 and 0.80. It measures 0 to 1 values.

Air Leakage (AL)

Air Leakage (AL) gauges the level at which air passes through corners and joints in home windows. It’s measured in cubic feet, starting from the air that passes through one square foot of the window’s area per 60 seconds.

The lower the AL measurement, the less leakage there is. This means that the windows with low AL measurement will yield better energy efficiency performance. Building codes and most industry standards require an AL of 0.3 cf-m/ft². 

Visible Transmittance

The Visible Transmittance evaluates the level of light that pushes through the window. Similar to the Solar Heat Gain Coefficient, the Visible Transmittance is measured in values of 0 to 1. The typical range of Visible Transmittance sits between 0.20 and 0.80.

Windows with superior energy efficiency performance will have a high Visible Transmittance score because they let additional light go through.

Condensation Resistance

With a score between 0 and 100, this category determines how well home windows perform against build up of water or moisture.

Many mediocre window products don’t have a good Condensation Resistance score. Run-of-the-mill window manufacturers, who only care about churning out subpar products, will not pay attention to Condensation Resistance abilities of their windows.

Naturally, the good energy efficient windows will have a high Condensation Resistance score than those average ones.

What Makes Up Energy Efficient Windows?

Work with a windows installer with energy efficient products.

The rise in home technology and availability of better resources allowed window manufacturers to produce products with fantastic energy efficiency capabilities.

Due to this, many professional window contractors provide energy efficient windows to demand the needs of environmentally conscious consumers.

And since more and more consumers favor products with good energy efficiency ratings, they tend to look for and purchase those that meet the ratings and requirements set by the ENERGY STAR program.

Windows with high energy efficiency are constructed with a combination of engineering, physics, and high-quality materials.

The glass, sash, frames, and spacers are put together by experts to make sure that the windows are energy efficient.


More and more homeowners are choosing vinyl windows for their affordability and durability. They come in many different styles and options.

On top of that, they are low-maintenance and provides great energy efficiency features.

These replacement home windows come in a variety of framing options.

Energy efficient windows have different components.

Fiberglass. Like vinyl, this material can either be stuffed with foam for more insulation or hollowed out. Fiberglass, when used as a window frame, is low-maintenance, reliable, and sturdy.

Vinyl. This type of framing material can either be lined with foaming insulation or hollowed out if you wish. Vinyl frames also come in wider varieties. You can use other materials such as metal or wood to make it sturdier.

Aluminum. This material is sturdy and recyclable. Some designs incorporate thermal breaks, which can lower the heat-loss level.

Wood. Wood is a popular material – and for good reasons. A timeless favorite frame for windows, wood has decent insulation properties. However, one downside of this material is its not easily maintained or protected, mostly if it is not covered by aluminum or vinyl. 

Glass for Energy Efficient Windows

Low-E Glass

Window manufacturers introduced low-emissivity glass to increase energy efficiency features of windows. Since glass itself does not have good insulation properties, low-E glass was the perfect solution.

It’s manufactured with a combination of treatments, including reflective coating and invisible tinting. These treatments help the windows energy performance. Low-E glass also protects your valuables  from fading too quickly because of sun exposure.

Multi-Pane Glass

Older houses – usually those that are built in the 70’s or older – have single-pane windows. This type of home windows does not do anything for your energy conservation efforts.

If you have an older home, one of the first upgrades you must do is to replace these outdated, single-pane windows.

Double-pane – or multi-pane- windows – are the perfect upgrade. These windows are filled with odorless and safe gases, such as krypton or argon.

These gases are put between the panes. They create a great barrier, which then reduces heat transfer from either sides of the glass.

For optimized energy efficiency, go for multi-pane replacement windows.

Window Spacers

The panes must have the right distance for superior efficiency performance – and that’s where window spacers come in.

These are the materials used to maintain the proper distances between multi-pane windows. They are the brackets that hold the window panes along the frame and the window sash. 

Unfortunately, window spacers are often taken for granted. A lot of people don’t realize their role in energy efficiency.

Window spacers, much like energy conductors, decrease the thermal capabilities of windows. There are non-metallic window spacers you can use. These are ideal if you want to diminish heat transfer and insulate the sides of the panes.

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