Energy experts have determined that a large percentage of your home's energy
escapes through inefficient windows and doors that serve as heat drains. Often, the
windows and doors that would come with a new home were a builder's model,
designed to be inexpensive and easy to install. They were usually not engineered to be
energy-efficient nor made from high quality materials. Many of the existing windows
here on Cape Cod today, would not meet standard code qualifications for today's new
construction and remodeling purposes.
Energy costs are rising every year. The cost of heating your home whether you use oil,
natural gas, propane or electricity is higher than ever. Are you willing to allow the
money you spend on heating and cooling your home to go to waste as it escapes
through your drafty windows and doors?
Window and door replacement is one of the best ways to improve your home's energy
efficiency, with the potential to save you thousands of dollars over the years to come.
Window glass was revolutionized in the 1970's. Insulated glass (two or more pieces of glass with a
dead air space between) made its debut in the early 70's. Low E glass was introduced in 1979. The E
stands for emissivity. Low E glass works by reflecting heat back to its source. It does this by utilizing
an ultra thin metallic coating on or in the glass.
Among other things, sunlight contains visible light, UV light, and infrared (IR) light. Visible light
enables us to see things. Ultraviolet light damages your skin, wood, fabrics, and causes colors to
Infrared light is basically heat. Low E glass has the ability to allow visible light to pass while blocking
certain amounts of UV light and IR light.
The infrared light in sunlight is powerful. When it strikes an object it heats it up. These objects can
be your tile floors, furniture, sidewalks, patio furniture, etc. As these objects cool off, they emit a low
powered form of IR light. Low E glass reflects this form of energy. In the summer this helps to keep
your house cooler, as the heat from objects outside is kept outside. In the winter, all objects in your
home are heated (by either the sun or your furnace). This heat is also bounced back into your house
by the low E glass.
There are two types of low E glass: hard coat and soft coat. Tin is applied directly to the molten glass
to make hard coat low E glass. It is hard to scratch the tin off the glass. The soft coat process
commonly involves the application of a thin layer of silver while the glass is in a vacuum. This coating
is delicate. Soft coat low E glass is always sandwiched with another piece of glass. It can also
oxidize if exposed to air. Argon gas is sometimes used to prevent this oxidation. This gas also acts
as an additional insulator.
Low E glass helps to reduce condensation on glass. The inside surface temperature of the glass is
warmer. The differences can be dramatic. Imagine a cold night with an outside temperature of 0
degrees and a 15 mph wind. The inside temperature of a single pane window would be
approximately 26 degrees. Regular double pane glass might register 35 degrees. Hard coat low E
glass would be very near 49 degrees. And weighing in at champ would be soft coat low E glass at 62
Some glass manufacturers have gone even farther. They have suspended thin, low E transparent
films in between pieces of glass. This system has excellent performance characteristics. Some of
these films can block 99.5 percent of UV light. Some boast an insulating value twice that of soft coat
low E glass.
Low E glass is worth the price, especially since houses tend to lose 25 percent of their heat through
Insulated Low E Glass
Taylor Building and Remodeling