Welcome to City Window & Glass

Glass Options

Window glass has come a long way since the days when only a single pane of glass sat between you and the elements of nature. There are many more options for today’s windows when it comes to glass. Learning about these different options may take some time, but it will surely pay off in increased comfort and energy savings.

Single-pane Glass
If you owned a gas guzzling 1970 Buick, you would surely want to trade it in with gas prices as they are today. Well, windows with one pane of glass literally suck the energy dollars from the home and offer little in protection from heat and cold. Excessive heat loss in the winter months equates to cold drafts and high utility bills. If you have single pane windows with or without a storm window, consider upgrading your windows with today’s insulated glass systems.

Insulated Glass
Insulated glass (IG), a key component for total window performance, offers year-round thermal performance and durability. Insulated glass, also called double glazing, is made up of two panes of glass separated by an air space. The air space provides the insulating value by reducing the transfer of heat flow between the inside and outside. Insulated glass offers several advantages for new construction and replacement window projects, including:

Improved condensation resistance
Better sound control
Increased wind load resistance
Glass configuration options to control winter heat loss and summer solar heat gain

Warm-Edge Spacer Technology
The material used to create the air space between the two panes of glass in insulated glass is called the spacer. To reduce heat transfer near the edge of a window, low conductance spacers, or warm-edge spacers, are used. Different technologies exist to keep the edge of the windows warmer, preventing heat loss and reducing condensation around the edges of the window.

Gas Filled IG Units
In some IG units manufacturers will fill the air space with argon or krypton gas. Argon and krypton gas are less conductive than air, which further reduces the heat transfer between the inside and outside. Argon gas is nontoxic, non-reactive, clear, and odorless. Krypton gas has better thermal performance than argon, but is more expensive to produce. The use of a less conductive gas in IG units has insulating benefits but comes at a higher initial cost.

Specialty Glass
There are other types of glass available primarily to obscure views while still allowing in light. Different patterns are available to suit almost any style. These glass options are typically used in bathrooms and other rooms where privacy and light is desired.

Laminated Glass
Laminated glass consists of a tough protective interlayer made of polyvinyl butyral (PVB) bonded together between two panes of glass under heat and pressure. Once sealed together, the glass behaves as a single unit and looks like normal glass. Similar to the glass in car windshields, laminated glass may break upon impact, but the glass fragments tend to adhere to the protective interlayer rather than falling free and potentially causing injury.

Tempered Glass
To create tempered glass, ordinary glass is heated to around 680 degrees Celsius (1256 degrees Fahrenheit) and then cooled rapidly by blowing air on both sides. This manufacturing process can make the tempered glass up to four times stronger than ordinary glass. When tempered glass breaks, it shatters into small blunt fragments, reducing the risk of serious injury.
Safety codes require tempered glass in all doors (including patio doors) and in windows that are located near doors, bathtubs or showers.

Tinted Glass
There are various types of tinted glass such as double glazed with high-performance tinted glass and single glazed with bronze or gray tints. One differentiating factor is how much light is passed through – also known as visible transmittance or VT.

Tinted glass has no effect on the U-factor but reduces solar heat gain which may be beneficial in the summer but a liability in the winter depending on where you live.

Windows Can Account For Up To 30% of Energy Consumed Annually
Windows can be a major source of heat loss in winter and heat gain in summer. The principle energy concerns for windows include U-Value and Solar Heat Gain (SHGC). U-Value measures how well a window prevents heat from escaping the home. Solar heat gain measures how well a window blocks heat from the sun.

These values are expressed as a number between 0 and 1. The lower the value, the better the window is at preventing heat loss or blocking the sun’s heat. Look for these factors when comparing different windows and options.

	In warm weather, Low-E glass reflects the sun's heat and reduces solar heat gain.
	In cold weather, Low-E glass reflects the heat back into the home, reducing heat loss.

Window Materials Influence Efficiency
With today’s advanced window systems there are many features to consider when deciding on the right window for your home. Window frames come in different materials and vary in performance. And, because the glass makes up the greatest proportion of area in a window, you should review all of the glass options available—from Low-E coatings and tinted glass to insulated glass units with warm edge spacers.