The glass (high performance glazing) which goes inside your structure, doors, or windows is a very important decision. There are thousands of different glass types on the market today, so the choices can become overwhelming when the consumer does not understand glazing terminology and process. Solar Innovations® is here to help assist in this process. The following paragraphs discuss the basics on understanding glass types and lays out a format for picking the right glass. There are three major types of glass, some of which you may have heard.

Glass Type

The most primitive type of glass is annealed glass. This glass is found in kitchen cabinets and glass vases. When this glass breaks it shatters into sharp jagged pieces and falls to the floor. Solar Innovations® does not use annealed glass.

The next type of glass is tempered glass. Many people have heard of this type. This glass is incredibly strong and is not prone to breaking. However, when it does break, it shatters into small squares and collapses. Solar Innovations® uses tempered glass in its doors, windows, and the walls of its glass structures.

The third type of glass is laminated glass. This glass consists of two pieces of glass formed together with a polyvinyl butryal (PVB) inter layer. The PVB is invisible to the eye but acts as glue to hold the pieces together. Upon impact, the glass breaks into pieces that look like a spider web, but it does not fall out of the frame. Car windshields are often made out of this glass. Solar Innovations® uses this type of glass in the roofs of its glass structures. If the glass in the roof breaks, it will splinter but will not fall on a person’s head. The majority of building codes across the country require laminated glass in roofing. Another benefit to laminated glass is that 99% of all harmful UV rays are removed when laminated glass is utilized.

Please Note: When internal dividers are used in an insulating glass unit, such as grilles, muntin bars, or simulated divided lites, there is the potential that dividers will contact the airspace glass surfaces (surface #2 and #3) of the insulating glass unit.

This can occur: When the insulating glass unit airspace pressure is below the atmospheric pressure (IG unit is concave).

This is caused by: Cold temperature conditions, high barometric pressure conditions, the insulated glass unites or windows are being shipped to an altitude below the insulated glass fabrication altitude, fabrication of insulating glass units where the insulated glass unit airspace thickness tolerance is at a lower limit, buffeting wind conditions, or fabrication of tempered insulting glass units where the tempered glass has a bow in the glass

When the metal dividers contact the airspace glass surfaces, there is the potential for having condensation on the room side (#4 glass surface) immediately behind the metal divider. This is because the insulating glass unit has lost its insulating value where the divider contacts the glass surfaces, causing the indoor glass surface to be colder. Therefore, there is more opportunity to have room side condensation with internal grilles than with standard insulating glass products that do not contain these grilles. 

The information above was provided by Cardinal IG – to read Cardinal’s entire technical bulletin on this matter, please click here.

Glass Units

After the glass type is chosen, it is time to choose the pane. There is double pane (insulated) and single pane (monolithic) glass available. Insulated glass consists of two pieces of glass in a unit with an air space between the two pieces. This glass unit is commonly found in all new windows. The air space and second piece of glass helps to insulate the room. Cold air or hot sunlight has to pass through the air and the second piece of glass. The insulated unit greatly helps to manage the interior temperatures.

Monolithic glass consists of only one piece of glass. This is not recommended for any applications where there will be wind or water touching the glass. If there is a blizzard outside, the snow will touch the glass, make it cold, and the bitter temperature will pass into the home. An interior application, such as a folding wall partition to divide a dining room and living room, is very well suited for monolithic glass.

Glass Tint

Now that the unit is picked, a tint must be selected. This is where the application of the glass is needed. There are generally two categories to pick between: color tint and LowE. Color tints are just as they sound. A color is added to the glass for aesthetics or for a specific purpose. Blues and greens are often used along coastal areas to enhance the look of a commercial or residential building. Grays and bronze tints are used for privacy and sometimes can be used for controlling light. Other colors, such as purple and red, are available when required.

When light entering a room is an issue, low emissions (LowE) glass should be used. There is a slight coating adhered to the glass which is the LowE. It is barely visible to the naked eye. Only when held next to a piece of uncoated glass can a difference in appearance be noticed.

The glass reduces the amount of sunlight entering a room. This helps to cut down on extreme heat build-up which make sunrooms and conservatories unpleasant. Another large benefit to LowE glass is the reduction of UV-rays which penetrate a room. This means that objects in the room that are pront ot fading such as furniture and draperies, will retain their color longer, because the fading is slower than an uncoated piece of glass.

The application of the glass is key here. Growing plants under LowE glass requires a specific type, whereas if people are the main occupants, then the strongest LowE can be utilized. The following link discusses applications for different kinds of glass. There are several different levels of LowE which are illustrated in the lower chart.

Common LowE Glass Types

Type Clear Insulated LoE 272 LoE 366 LoE 240 LoE i89
(with 366 & Argon)
Clear Over Clear 272 366 LoE 240
Suitable for Plants Yes Yes No Roof = Yes No
Suitable for People Yes Yes Yes Yes Yes
Light Transmittance 81% 72% 66% 40% 58%
U Value 0.48 0.30 .20 0.3 0.2
Solar Heat Gain Coefficient 0.76 0.41 0.27 0.25 0.25
Special Benefits None Cuts down on UV rays which burn plants but still lets in enough light for plants growth. Lets more light in than other options but keeps more heat out. Excellent fading protection. Ideal for reducing glares. Can be used in roof for plants with 272 in the walls. Triple pane performance requiring only double pane glass.
Click here to download Solar Innovations, Inc.’s Glass Chart

366 offers Solar control with year round comfort.  This type of glass blocks solar gain and assists in energy savings. During the hot months of summer, heat is kept out of a room, while in the winter, the heat is retained in the space.  These factors will assist in reducing your heating and cooling costs. 366 also has a high visibility.  The naked eye will not notice a difference.  The glass is not cloudy or tinted bronze.  The glass will block 95% of UV rays, which increases fading control to your furnishings, draperies, and flooring.

272 is the clearest option in LowE glasses.  The color difference is only noticeable when placed next to a clear piece of glass.  This ensures a natural view from your windows.  The glass reflects heat in summer and captures heat in winter which offers energy savings.  272 blocks 84% of UV rays, aiding in the preservation of your interior furnishings and finishes.

 240 is the best LowE option for glare control.  This glass type absorbs 60% of sunlight, which reduces the amount of light entering a space to 40%.   The glass has a slight tint due to its glare control, which looks like a slight blue when closely inspected.  84% of UV rays are blocked.

For more information on Solar Innovations, Inc.’s Glazing Pages, please visit the links below:

LowE 272 | LowE 240 | LowE 366  | EZ Clean | Dynamic | Solera