If you’re interested in the thermal performance of insulated glass units for your home, today we will discuss everything you should know about these glass units. Let’s begin with a definition: insulated glass is a glass unit that’s composed of two or more glass planes separated by inter gas. They’re also known as double-pane or double glazing. So, each of the panes on this glass unit is separated by a space that’s filled with inert gas, often argon, krypton, or a mix of both.
Types of Insulated Glass Units
There are different types of insulated glass units available. The first one is the single-pane, which consists of a single layer of glass, which doesn’t make it a great insulator but it can be ideal for spaces that don’t need much insulation, such as garages, and they’re very inexpensive.
Then we have the double-pane glass units, which consist of two layers of glass separated by gas, air, or an insulating sheet. These glass units are durable, they will protect the home from cold temperatures, maintain A/C in the summer, make a good sound buffer, and Low-E coatings that prevent UV rays from coming in. They are an investment, but worth it in most cases.
Triple-pane glass units are also available and they consist of three layers of glass, separated by two dehydrated and hermetically sealed spaces. This makes the units super-insulating, which is particularly useful for applications where a low u-value is required. In case you’re not familiar, u-value is the sum of the thermal resistances of the layers of a building element, such as walls, floors, etc., the lower the u-value, and the better insulation.
And last but not least, we have Low-E or low-emissivity glass units, which minimize the amount of UV and infrared light that comes through the glass without affecting the amount of light that gets in. Low-E units have a super-thin transparent coating, so it doesn’t affect the clarity of the glass. These coatings reflect the interior temperature back inside which keeps the temperature in your home consistent.
Types of Glass for Insulated Windows
Your insulated windows can have different types of glasses to suit your needs. For one, there’s tinted glass, which means the glass is slightly colored to reduce heat absorption and glare. Tinted windows can be gray, bronze, which blocks visible light and heat, as well as green and blue, which blocks the heat but not the light. You want to avoid dark tint colors such as black because it would make the room too dark and they provide little benefits.
There’s also double-glazed or triple-glazed glass, which is made of two or three glass panes respectively with air between the spaces of the glass layers. The air between the layers serves as a barrier and it reduces the amount of heat that can be transferred through the window. Remember u-value? Well, that’s what heat transfer is. The lower the u-value, the better the insulation. Sometimes manufacturers will use gas, such as argon, instead of air between the layers.
Another option is Low-E coatings, which are super thin layers of metal oxide or metal applied to the glass. It gives the glass a subtle green tint under the right lighting conditions, so don’t worry about color. Low-E glass windows have low u-value and they’re more effective than gas or air vacuum between the layers according to the US Department of Energy. Some Low-E coatings will be spectrally selective, meaning they allow certain types of light without darkening the room, and others don’t function like this and they will block some of the natural light coming in.
Last but not least, we have reflective coatings that can be done in gold, silver, bronze, and other colors. As their name suggests, these coatings are shiny, which causes the window to look like a mirror from the outside. Reflective coatings are effective against glare and heat transfer when direct sunlight hits them. They block out much of the light as well, which is why they’re usually used for offices and industrial buildings instead of homes.
Further Categories of Insulated Glass Units
There are three categories for insulated glass units that are worth discussing: annealed glass, tempered glass, and heat strengthened glass. Annealed glass is the glass that comes from the primary factory, referred to as the float plant. Most architectural glass is made of silica sand, limestone, soda ash, dolomite, and salt cake brought to 2700 degrees F., which is then floated out on top of a pool of molten tin. Then, it’s pulled into a long conveyor to pass through a furnace that controls the cooling process. Thus producing a cool, flat, solidified clear material known as annealed glass.
Tempered glass is made more resistant to blunt impact through the tempering process. It also makes the glass less of a hazard if broken because it won’t explode into a million pieces. Tempered glass is also known as safety glass for this reason, and it’s commonly used in shower doors, doors, glass handrails, and more. Tempered glass is made heating it in a tempering oven and then cooling it super-fast. This kind of glass is 4 to 5 times stronger than annealed glass.
Finally, there’s heat strengthened glass, which is placed in a tempering oven until it reaches 1100 to 1500 degrees F, then cooled super quickly. This type of glass is two times stronger than annealed glass and it can tolerate rapid or uneven temperature swings. It can be improved with insulation, Low-E coatings, back-paint, and uneven shading as well.
Which Insulated Glass Unit Provides More Efficient Thermal Resistance?
Low-E glass seems to provide the most efficient thermal resistance among insulated glass units because of its low u-value. However, any other type of insulated glass described here today will do a great insulating job. It’s a matter of knowing your needs and finding the right option for you!
Conclusion
Insulated glass units are available in many different types and they provide a ton of benefits for your home. In case you’re wondering if you can replace insulated glass windows yourself, the answer is yes, and a New York Times article will teach you how!
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