When it's time to buy or repair your home's windows, you may hear a variety of words and terms that are unfamiliar. "Glazing" is one of those words.
When you're buying new windows, the type of window glazing you choose will affect your window's performance and energy efficiency. If you're repairing old windows, glazing will play an important role in your repair project.
Here’s what every homeowner should know and what we will cover:
Window glazing is the glass found in modern windows. Window glazing comes in different types to improve energy efficiency and comfort inside the home. Each type of window glaze has its pros and cons. The type of glazing that will best meet your needs depends on your priorities, budget and the level of efficiency you expect from your windows (1).
Also known as "single pane," single glaze windows are the least energy efficient kind of windows on the market. A single layer of glass does very little to protect the home from fluctuating hot and cold outdoor temperatures. At one time, single glaze windows were the only type of windows available in home construction, but those days are long gone (2, 3).
Single glaze windows are now somewhat uncommon because they offer no real insulation, which makes it hard to regulate temperatures in the home. Single glaze windows also force the home's HVAC system to run harder than necessary to do its job. This causes wear and tear on the HVAC system and can shorten the service life of your furnace or air conditioner.
Homeowners who do opt for single glaze windows in their home can benefit from storm windows in the winter. Storm windows improve the efficiency of single pane windows by providing a layer of insulation between the outside world and the window.
Double glaze windows are cost effective and efficient. They make up the majority of windows sold today. Also called "dual pane" or "double pane," double glaze windows consist of two sheets of glass with a space in the middle. Double glaze windows do not need storm windows in order to be energy efficient (4, 5).
Typically, the space in the middle is filled with argon, an odorless, non-toxic gas. Compared to air, argon is a poor heat conductor and is therefore a better insulator. Over time, the gas from double glaze windows may leak out, so after many years of use some homeowners will have the gas refilled. Your window contractor can determine whether or not your gas filled windows need more gas and can also talk to you about maintaining your double glaze windows (6).
Triple glaze windows consist of three sheets of clear glaze, with gas-filled space in between. Triple glaze is the most energy efficient type of window available, however, the higher price, thick construction and the extra weight of triple pane windows make them less popular among homeowners. Triple glaze windows are more commonly found in cold weather climates (7).
Low-E glaze, also called "Low-Emissivity" glaze, is a type of glass coated in metallic oxide. This invisible layer prevents heat from passing through the glass by reflecting UV rays back into the atmosphere. Low-E glaze is often used on double pane and triple pane windows to increase the energy efficiency without adding to the weight of the window.
Windows with Low-E glaze cost slightly more than windows without, but reduced utility bills help homeowners recover those costs in 5 to 10 years. In addition, there are other benefits to Low-E glaze which can help justify the cost. These benefits include:
Even though Low-E glaze prevents UV rays from entering the home, visible sunlight is allowed to enter. Low-E glaze is invisible and does not tint the windows. Low-E coating also prevents heat loss in the winter, to help homeowners maintain comfortable temperatures throughout the year (8, 9).
The type of glazing you choose for your home will have a lasting impact on your home's energy efficiency. Work with your window contractor to determine which type of windows will perform to your standards (10).
Glazing compound is the putty that holds pieces of glass in place in older window sashes. Glazing compound improves the energy efficiency of older windows by preventing drafts and sealing the space between the sash and the glass. Glazing compound is not used in modern windows (11).
Glazing compound is designed to last for decades, but the length of time that glazing lasts will depend on the quality of the putty as well as the quality of the work when the glazing was installed. You'll know when glazing putty needs to be removed and reinstalled when the glaze begins to crack and fall off. Glazing compound may also need to be replaced when the window is broken or damaged. Homeowners who aren't sure if it's time to re-glaze their windows can talk to a window contractor for more advice (12).
Here are high-level steps:
Once this job is done, your windows should be in good shape for many years. If you don't feel comfortable removing the sashes from your windows, or if you question your ability to properly remove old glaze and install new glaze, contact a window contractor for help. Your window contractor can either repair your old windows or give you a quote for new windows. Modern windows do not require glazing, so many homeowners with old windows eventually decide to transition to new windows.
For more information about window glaze and other modern window features, visit a showroom in your area. Your window contractor can show you all the latest window technology.