If you’ve ever seen an early 1900s window, you would discover that it has many ripples in the single pane of glass set into a wooden frame - which is really different from the most energy-efficient, double-paned, vinyl framed windows we have nowadays.
In the 1970s, insulated windows - two or more pieces of glass with dead air between them - made their first appearance in the 1970’s, amidst the steady improvements of window glass technology through the decades. The windows restricted the change in temperature and cut down on condensation by providing dead air space.
A decade later, low-e glass was introduced. Low-e coatings are extremely thin layers of metallic oxide that are bonded to the surface of the window’s glass to prevent heat and ultra-violet (UV) rays from coming through them. Due to this, windows have become more effective at keeping heat out during summer and in during winter.
While invisible to the human eye, infrared or UV rays makeup most of the sun’s energy. While we know UV rays can cause sunburns, they can also fade furnishings and finishes inside the home. Infrared rays heat up the asphalt outside and even your flooring and furniture indoors. If you let it in, infrared heat can affect your home even after the sun sets because this heat is retained and released as the air around them cools.
Low-e coated glass, however, reflects selected portions of the light spectrum back out through the windows, meaning the inside of the home stays cooler, not only during the sunny part of the day, but later as well.
The low-e glass comes in hard coat and soft coat. To make hard coat, tin is applied directly to the molten glass. In the soft coat’s case, a thin layer of silver is applied to the glass in a vacuum. Always sandwiched with another piece of glass, soft coat low-e glass is easily damaged. To prevent oxidation and to act as an additional insulator, Argon gas is often used between panes.
A third type of low-e glass is heat mirror, which includes a thin polyester sheet suspended between the two panes of a dual pane window. If you live in extreme climates, the coating reflects radiant heat and the sheet decreases heat loss, which makes this the best option for you. These films block as much as 99.5 percent of UV light and increase insulation by as much as 100 percent.
Be certain that the kind of windows you want are a match for the climate in which you live in before buying them. The Energy Star or National Fenestration Rating Council (NFRC) label is what you need to find for that. Included in the NFRC label should be the U-value and the solar heat gain coefficient (SHGC) for the window. Although there is no SHGC requirement because solar heat gain is not an issue to comply with Energy Star standards, in the colder areas the U-factor should be .35 or less, while in the hottest areas windows should have an SHCG rating of .4 or lower and a U-factor of .75 or lower.
Author bio: Robert Butcher is a freelance writer and currently publishes reviews of best web hosting and unlimited web hosting. Top pick ChimeHost has packages suitable for both individuals and small businesses that come with advanced tools to help clients start a website at a low cost.