Why Low-E
The effect on the comfort level of a home’s occupants is one reason home builders like Low-E windows. Low-E
has the ability to keep the temperature of the surface of the glass facing the
interior very near that of the room itself, regardless of outside temperatures.
For example if it is 0 degrees F outside, the inside surface of double pane
glass can be as much as 30 degrees warmer than single pane glass but still 25
degrees lower than Low-E coated glass. The converse can be true during hot
summer months.
Another great reason for Low-E windows is energy
efficiency. They are energy efficient because any material that reflects,
absorbs, and emits radiant energy is going to save energy. Regular uncoated
glass windows will take in heat during the day but release it right back out
through the glass at night. This is why in some houses a room can be very
hot during the day and freezing when the sun goes down. The result of this
heat transfer is using our heating and cooling appliances more than we need to.
No matter what type of Low-E windows you get, they will perform better than
windows that have only clear glass.
What is Low-E?
The ability of a material to radiate energy is known as
emissivity. In general, highly reflective materials have a low emissivity and
dull darker colored materials have a high emissivity. All materials, including
windows, radiate heat in the form of long-wave, infrared energy depending on
the emissivity and temperature of their surfaces. Radiant energy is one of the
important ways heat transfer occurs with windows. Reducing the emissivity of
one or more of the window glass surfaces improves a window’s insulating
properties.
Low-e coatings have been developed to minimize the amount of
ultraviolet and infrared light that can pass through glass without compromising
the amount of visible light that is transmitted. Low-e glass has a
microscopically thin, transparent coating – it is much thinner than a human
hair – that reflects long-wave infrared energy (or heat). When the interior
heat energy tries to escape to the colder outside during the winter, the low-e
coating reflects the heat back to the inside, reducing the radiant heat loss
through the glass. The reverse happens during the summer time.
What Low-E Is Not
Low-E is not the same as tinted glass. Tinting is the adding
of alloying materials to the glass itself. Also, tinted glass tends to absorb
sunlight and will get very hot when installed as a single pane, hence tinting
does not improve insulating value.
The Future of Low-E
By changing the types of materials used in the ‘stack’ or layers of Low-E, or by increasing or decreasing the number of layers, we can now get more specific in choosing glass which will meet our exact project needs. Need high visible light but low U values? There’s a Low-E for that. Need greater protection from fading? There’s a Low-E for that. And it gets even more specific than that. Adding argon gas to the captive air space, as we all know, will improve insulating value. Adding various tinting agents to the glass itself will allow for even further refinement of the glass’s performance.
Is moving to a brand new home with Low-E windows and
other high-end details on your mind? Contact The Boehmer Team. We can help.
