You'll find that you have several options to consider when selecting the type of skylight to use in your home.
When selecting a skylight for energy efficiency, it's important to first consider its energy performance ratings in relation to your climate and home's design. This will help narrow your selection.
A skylight's energy efficiency is dependent upon all of its components:
- Glazing
- Operation and Use
- Shape
Skylight Glazing
When selecting a skylight for your home, it's important to consider what type of glazing you should use to improve your home's energy efficiency. Based on various skylight design factors 'such as its orientation and your climate' you may even want different types of glazing for different skylights throughout your home.
Skylight glazing usually consists of either plastic or glass. Other glazing technologies may also be used for solar heat control.
Plastic Glazing
Plastic glazing is usually inexpensive and less liable to break than most other glazing materials. However, these plastic surfaces scratch easily, and they may become brittle and discolored over time. Many plastics also allow most of the ultraviolet (UV) rays in (unless the glazing is coated with a special film), which increases fading damage to furnishings. Acrylics and polycarbonates are the most commonly used plastic glazing. Acrylics are weaker than polycarbonates, but cost less. Although polycarbonates offer high impact resistance, some yellow with age.
Plastic glazing is usually inexpensive and less liable to break than most other glazing materials. However, these plastic surfaces scratch easily, and they may become brittle and discolored over time. Many plastics also allow most of the ultraviolet (UV) rays in (unless the glazing is coated with a special film), which increases fading damage to furnishings. Acrylics and polycarbonates are the most commonly used plastic glazing. Acrylics are weaker than polycarbonates, but cost less. Although polycarbonates offer high impact resistance, some yellow with age.
Glass
Glass is usually found on the more expensive skylights. Glass is more durable than plastics and does not discolor. All glass used for skylights must be made of 'safety glazing,' a generic term for both tempered and laminated glass. Tempered glass is the most impact resistant. Laminated glass is fabricated with a thin layer of plastic embedded near the center of the glass. Both keep the glass from breaking into large, sharp pieces. Skylights are often made with a tempered glass on the exterior side and a laminated pane on the interior side. This arrangement gives maximum impact resistance while protecting occupants from falling shards of glass.
Glass is usually found on the more expensive skylights. Glass is more durable than plastics and does not discolor. All glass used for skylights must be made of 'safety glazing,' a generic term for both tempered and laminated glass. Tempered glass is the most impact resistant. Laminated glass is fabricated with a thin layer of plastic embedded near the center of the glass. Both keep the glass from breaking into large, sharp pieces. Skylights are often made with a tempered glass on the exterior side and a laminated pane on the interior side. This arrangement gives maximum impact resistance while protecting occupants from falling shards of glass.
Solar Heat Control Glazing Because skylights are located on the roofs, they can result in large amounts of unwanted summer time solar heat gains and winter time heat losses. Manufacturers use various glazing technologies to reduce these impacts. The most common technologies include those also used for window glazing:
- Heat-absorbing tints
- Insulated glazing (double-glazed, triple-glazed)
- Low-emissivity (Low-E) coatings.
Some manufacturers even install a translucent insulation material between several glazing layers to create a more thermally efficient assembly.
Courtesy of the U.S. Department of Energy
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By Jay Leone
Laminated Tempered Safety Glass
Tempered glass and laminated glass have different properties. They are two different types of glass but can be used together in some applications. Laminated, tempered glass is a common marriage of the two types of glass. Separately, each type of glass has useful applications.
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History
The chemist Edouard Benedictus invented laminated glass in 1903. He hoped that the glass-plastic combination would reduce car-related injuries. His invention however, was not used in automobiles for several years. The idea of tempered glass has been around for centuries. Rudolph Seiden of Austira was the first to patent a design for tempered glass.
Applications
Tempered Glass Screen Protector
Tempered glass is commonly used in frameless glass doors used in commercial settings. Passenger windows in vehicles are usually made of tempered glass. The windshields in automobiles are typically made of laminated glass, as is the glass commonly used in skylights. Laminated glass is often used in applications where there is a severe risk of high winds.
Laminated Glass
Laminated glass is produced by bonding layers of glass together under pressure and heat, with a resin called PVB (polyvinyl butyral). This technique is used to create single sheets of glass with multiple layers. The PVB keeps the glass from breaking apart easily and provides high sound insulation. Laminated glass will flex before shattering. Laminated glass is strong but not as strong as tempered glass. Also, laminated glass blocks nearly 99 percent of ultraviolet light transmission.
Tempered Glass
Tempered glass is also sometimes called toughened glass. It is very strong and is often used as safety glass. When tempered glass is broken, it will usually break into very small pieces instead of into big shards. This makes it less likely to cut a person. Tempered glass is known to be several times stronger than laminated glass. Tempered glass is created using chemical and thermal treatments. The treatments give it more balanced internal stress capabilities.
Cost
Laminated glass is generally more expensive then tempered glass. Until recently, laminated glazings used to cost three to four times as much as tempered glass. It is mandatory for car manufacturers to use laminated glass in windshields. More companies are using laminated glass in side and rear windows.
Laminated Tempered Glass
The science behind laminated glass and tempered glass can be combined to make laminated glass that is also tempered. When manufacturing this type of glass, the thickness of PVB used has to be just right or some level of bubbling can occur at the edges. This is a difficult process but if successful, laminated tempered glass can have many useful applications. Many car manufacturers are using this technology in their windows now. However, most car companies still choose to use one method over the other.
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