Exterior windows

Understanding the Energy Rating System for High-Performance Windows

Insulating your home is not a matter of finding one perfect measure, but rather adding together the direct cumulative effects of windows and doors. To this end, high-performance windows are more of an umbrella category for windows that rate well on a bevy of environmental tests, rather than a single concrete market category. Most windows that qualify as high-performance are produced using sophisticated glazing technologies or other advanced window features like a separation layer filled with non-conductive gas. In this article, we will explain the basics of evaluating windows for their performance levels before detailing the process of window glazing. We will then discuss advanced window technologies available on the market and their costs. Understanding features before you purchase and install windows may save you money on energy for decades to come.

How are High-Performance Windows Evaluated?

Windows are evaluated by two main metrics. First, The Environmental Protection Agency sets product specifications across industries that are then marked with the Energy Star label.  Second, the National Fenestration Rating Council (NFRC) publicly publishes the results of performance tests they run on windows. Gaining Energy Star and NFRC approval requires solid results in the tested window features. For one, the solar heat gain coefficient (SHGC) determines the extent to which a window transfers heat energy from the sun. According to this guide from the governmental website on energy standards, higher solar heat transmission improves a window’s ability to maintain warmth in winter, while lower solar heat transmission helps keep a house cool during summertime. Different areas of a home with different shaded conditions and exposure to sunlight benefit from different SHGC values. However, solar heat is not the only way that windows transmit temperature.

Windows also transmit non-solar heat according to the manufacturing process and quality of the glass itself, the materials and construction of the frame, and all other aspects of the full window’s performance. Heat transfer through the glass can be stymied by glazing processes, the use of multiple layers, and spacing between those layers. We will explore window glazing in further detail in the next section.

The last property of window thermal efficiency that is measured for environmental ratings is air leakage. Air leakage must consider the full installation of the window and the specific construction of its frame and sealant. High air leakage indicates loose framing or poor pressure resistance. If installed in the wrong climate or elevation, a window with high air leakage can enable drafty conditions and higher utility bills depending on the season. When windows test within reasonable parameters for each of these categories, they will qualify as high-performance windows.

The Technology Behind Window Glazing

Much like “high-performance windows,” window glazing is another term that has multiple meanings with the same overall takeaway. Glazing refers to both windows constructed using multiple layers of glass and single-pane windows sealed with energy-efficient thermal putty and caulk. The former tends to be most convenient for people in the process of constructing a new home or investing in a full window replacement, while the latter is most useful for people working on a budget to shore up their home’s energy efficiency.

This is also the case for inhabitants of old and historical homes who want to keep the original windows. Window glazing compound is available at most hardware stores, and is relatively straightforward to apply. Just keep in mind that windows with multiple panes are many times more heat efficient than single-pane windows, even with good sealant.

If you are looking to invest in complete window replacements, you can acquire double or even triple-glazed windows. The biggest downside to doing so is the upfront cost. Double-glazed windows are much more expensive than single-pane windows. Their basic components include two panes of coated glass, mounted in window pane spacers in frames that are usually made of aluminum or wood. The space between the glass is filled with a noble gas, usually argon or krypton since they have very low thermal conductivity.

Triple-glazed windows are made of all the same parts, except a single pane of uncoated clear glass sits between for even better insulation. They have the added benefit of reducing outside noise. Keep in mind that glazed windows are one strategy in a multi-headed battle to reduce energy costs. Window features by themselves will not cut your energy bill if your door is still drafty, or there are other notable weaknesses in your home.

Saving Money on Value Windows and Doors

If you are looking for energy-efficient, high-value windows and doors for a reasonable price, your best bet is to talk directly with a contractor. Construction professionals with specialized experience in window and door replacement can source materials that consumers may not be able to, and that general contractors may have difficulty finding.

Contractors specializing in this form of work can also give you additional tips to better insulate your home from the elements.  Glazed windows will certainly help, but if a specialist can point out structural weaknesses in your home, they will become that much more effective. Another benefit of going through contractors to source your windows is that they often offer a variety of financing options. Offsetting the immediate cost of window replacement can go a long way to making this energy-saving measure more accessible.

Window Replacements for the Phoenix Area

Heat is an unavoidable fact of life for anyone living in Arizona long term. This is why high-performance windows are so critical for any complete home insulation plan. AZ Valley Windows has two decades of experience shoring up home defenses against high heat. We have a wide range of energy-efficient windows to choose from and work with a team of experienced installers to make sure your windows are implemented as efficiently and effectively as possible.  Our team does our best to make sure your new windows not only suit your energy needs but also the aesthetic of your home. We give a free in-home consultation for all customers, including a project estimate. Contact us today with your home project.

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