With Air-Tite's exclusive "Ask The Expert" section we provide customers with answers to frequently asked questions and specific inquiries to ensure that our customers have the knowledge required to make a purchase that can be enjoyed for years to come.

Q?  What is LOW E Glass? and why add it?


The question we at Air-Tite always get, is about Low-E windows. Whether or not they’re really energy efficient windows.  In short, Low-E means low emissivity, or more precisely, low thermal emissivity.  So yes, Low-E windows are energy efficient because any material that reflects, absorbs, and emits radiant energy is going to save energy.

In terms of window glass, it is by nature highly thermal emissive and clear glass absorbs a ton of energy without reflecting much. This means if you have clear glass in your windows, you are absorbing all of the heat energy from the sun as well as radiant heat from inside, but none of it is being put to use in creating energy efficient windows.  Any heat taken in through the glass during the day is being released right back out through the window 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 net result is that we end up using our heating and cooling appliances more than we need to.

To improve insulation or thermal efficiency in a window, a thin film coating is applied to the raw glass.  The process is done at the glass manufacturing plant where specially designed coatings are applied to one or more surfaces of an insulated glass unit.  For example: usually the glass is coated on the inside of the outer pane for double pane windows.  This film coating reflects radiant infrared energy, which is meant to keep the energy on the same side it originates from while still letting in visible light.  So when the sun shines, a Low-E coated window reflects a lot of that unwanted energy back towards the sun instead of letting the heat pass through the glass.  It works the same way if you are running your heater.  The energy from your heater comes up against the Low-E window and is reflected back toward the inside of the house so it isn’t lost.

There are a couple different methods used for coating Low-E windows.  Pyrolytic coatings are applied at very high temperatures at the plant when the glass is manufactured.  Pyrolytic coatings are usually tin dioxide and are also called ‘hard-coat’.  Hard coat Low-E glass surfaces are considered to be medium grade energy efficient windows and perform much better than plain clear glass.  The second method is called Magnetron Sputtering.  This process takes place when the glass is placed in a vacuum chamber and has several thin layers of silver with antireflective properties applied to it.  This is considered ‘soft-coat’ and must be enclosed in double-pane window units to protect it.  Soft coat Low-E glass is the most efficient and highest performing of the two energy efficient window types.  Soft coat Low-E windows are the type we sell at Air-Tite!

Q? Multi chambered frames vs. Insulated Frames- The Facts.


In a majority of the windows, it makes little difference.

It is a selling tool for the most part.

What does the foam filling in windows add to performance...from TruBlu

Foam-filled vinyl may provide some structural strength and consumer appeal, but the foam core adds little to the overall window energy performance. The following is from my favorite fenestration publication, ENERGY DESIGN UPDATE. For you pros, if you don't have a subscription to EDU you're missing out on a lot of good info. An online subscription costs about $2,500/year, and a mailed written subscription is I think about $400. They test new products, challenge claims, and analyze issues relating to windows, glazing, fenestration, energy-efficient buildings, etc. Good stuff. Anyway, a while back they had an article called "The Dubious Benefits of Foam-Filled Vinyl Windows." Here Goes:

Some manufacturers of vinyl-framed windows inject urethane foam into the hollow vinyl frame to improve thermal performance and/or increase rigidity. Although a foam-filled frame is visually impressive when viewed in cross section, the actual benefits in terms of energy performance are apparently minimal.

As part of a recent research project, Enermodal Engineering of Waterloo, Ontario, modeled the thermal performance of vinyl frames with and without foam insulation. The R-value of the hollow frame was R-2.0; the foam-filled frame was only slightly higher - R-2.3. In a climatic region with 6,000 degree days per year (Denver, for example), that boils down to energy savings less than 50,000 Btu per window per year - about 30 cents' worth of natural gas heat.

Impact on overall window R-value

When installed in a double-glazed window with low-E glass, the slight improvement in frame R-value produced by foam filling has little effect on overall window R-value. Using the WINDOW 4.0 computer program developed by Lawrence Berkeley Laboratory, we calculated the overall R-value of vinyl windows with and without foam filling. The results, listed in Table 1, show only 0.1 improvement in [total unit] R-value.

The figures in Table 1 are theoretical calculations, but at least one laboratory measurement bears them out. Quality Testing Inc. of Everett, Washington, ran a series of tests on vinyl windows with and without foam filling. The results, listed in Table 2, were very close to the theoretical results in Table 1.

Building codes, condensation, and trade fairs

Given the minimal energy benefit of foam-filled windows, might there be other practical advantages? Maybe. One researcher pointed out that some building energy codes require minimum R-2.5 for windows. In the examples listed in Tables 1 and 2, the uninsulated window would not qualify; the foam-filled window would.

What about moisture condensation resistance? Will the higher R-value in the frame make the window more resistant to condensation? Only minimally. Dave Perich at Louisiana Pacific (LP), which sells foam-filled vinyl windows, told EDU that LP tests show that at sub-zero outdoor temperatures, the interior surface of a foam filled vinyl frame is only about 3°F warmer than that of an uninsulated frame.


Q?  What is LOW E Glass?


Low-E Glass-Low-E is short for "Low Emissivity." It is a virtually invisible, silver coating that is applied to the glass surface. It reflects room side infrared energy back into the room (reducing the U-Value) and rejects the sun's heat and UV rays (reducing the SHGC).

Q?  What is argon gas and why is it used?


It is a colorless, odorless inert gas. It is injected into the airspace between the glass lites. It is used to increase the thermal performance of the insulated glass.

Q?  What is krypton and why is it used?


It is aso colorless, odorless inert gas, much like argon. It is slightly more efficient than argon; however, it is a more expensive option.

Q?  What are various types of glass and what are some examples of recommended uses?


Flat/Plate/Annealed Glass-Float, Plate, and annealed glass, in general, are interchangeable terms. This glass comes in varying thicknesses ranging from 1/16" and larger and is standard in the industry.

Single-Strength glass = 1/16" on each pane

Double-Strength glass = 1/8" on each pane

Q?  What is tempered Glass?


Tempered Glass-Tempered glass is also commonly called "heat-strengthened" because its resistance to breakage. It is common industry knowledge that tempered glass is four times stronger than annealed glass. Although tempered glass is glass is stronger along the face, it is very fragile along its edges.

Glass is strengthened when it goes through a heat process and becomes "tempered." The heat causes glass to change its chemical makeup, so when it breaks, it will break into small "pebbles." Tempered glass is required to be used in doors and in some situations windows.

Q?  What is Laminated Glass?


Laminated glass has a translucent "plastic" layer. Think of laminated glass as a sandwich with two layers of glass as the bread and the plastic layer as the meat. Laminated glass is used in vehicle windshields, hurricane prone areas, and often for theft deterrence.

Q?  What is Solar Heat Gain Coefficient (SHGC)?


This is a value that measures the transfer of solar energy/radiation. Values are measured between 1 and 0. The lower the number, the less solar energy/radiation is transferred.

Q?  What is Insulated Glass?


Insulated glass is a general term that signifies two panes of glass separated by a spacer. The space in between the 2 panes is sealed, making this space "dead air." Dead air space has insulating qualities, making "insulated glass" more energy efficient.

Q?  What is CAPPING?


In construction capping or window capping (window claddingwindow wrapping) refers to the application of aluminum or vinyl sheeting cut and formed with a brake (bender) to fit over the exterior, wood trim of a building. The aluminum is intended to make aging trim with peeling paint look better, reduce future paint maintenance, and provide a weather-proof layer to control the infiltration of air and water.

Q?  What is the difference between Virgin Vinyl Vs Recycled Vinyl Windows?


Vinyl is a man-made synthetic first invented in the 1920s by combining ethylene, a product found in crude oil, and chlorine, a product in found in regular salt. When processed, these substances are combined to make Polyvinyl Chloride (PVC) resin, commonly known as vinyl. Manufacturers quickly incorporated vinyl into common household items like windows, siding and flooring because it was stronger, more durable, and cheaper than other materials.

Since vinyl is a man-made product, it can also be recycled and used again in new products including new windows. This is an inexpensive process for window manufacturers so you’ll find a lot of these products on the market.

There are three types of vinyl windows on the market today. Each variation has different amounts of virgin and recycled vinyl in its make-up. While the end products may appear  identical, the type of window produced varies greatly in quality and durability.

How can you tell the difference between virgin and recycled vinyl? The information should be easily available from the manufacturer if you are asking the right questions. LETS COMPARE THE COLOR WHITE/ AND COMPOSITION FOR INSTANCE.

Q?  Why Virgin Vinyl?


SOFT WHITE COMPLEXION:  First generation vinyl windows include no recycled material. These are the strongest and most durable type of vinyl windows. Not surprisingly, these will also be more expensive than recycled windows- THIS IS WHAT WE USE AT AIR-TITE.

Q?  Combination of Virgin Vinyl and Recycled Vinyl


SLIGHTLY BLUEISH WHITE COMPLEXION: This will sometimes be referred to as 100% virgin vinyl because a portion of the product does actually include first generation, virgin vinyl but the rest is made of recycled materials. The ratio of virgin to recycled vinyl determines the quality. If the product has the VSI (Vinyl Siding Institute) stamp on it, it is likely to be of higher quality even if it is not actually all virgin, first generation vinyl. USED BY MOST COMPETITORS.

Q?  Recycled (or Reground) Vinyl – WARNING: LOOKS LIKE A BLUEISH BRIGHT WHITE.


This product creates a weaker window frame and is not as durable as either the true virgin vinyl window or the combination of first generation vinyl and recycled materials. It tends to become brittle and crack, warp and/or fade more quickly. SOLD AT MOST HOME CENTERS.

Q?  How can I stop condensation from forming on my windows?


Condensation, or fog, on windows, is actually caused by humidity, or water vapor. Humidity is present in almost all air. When this water vapor comes in contact with a surface that is at a cooler temperature, the vapor turns to visible droplets of liquid, or condensation.

  • Use a dehumidifier.
  • Make sure you windows are well ventilated and that air is blowing across the surface of the windows.
  • Keep you mini-blinds open to help increase ventilation and air movement.
  • Reduce the amount of plants near your windows.
  • Use exhaust fans when you are cooking.

Q?  Can windows really lower my energy bills?


YES!  If your windows are more than 10 years old, you are probably losing valuable heat and/or air conditioning through them every day! How? Windows can lose heat in three major ways: through the glass, around the sides of the window and from conduction that occurs through the window frame. The end result? in the winter, you end up constantly trying to heat the air from the outside! and in the summer, your air conditioning system has to work twice as hard trying to cool it.

Q?  What is tempered glass?


Tempered glass is glass that has first been cut to size, then heated to a very high temperature and then rapidly brought back to room temperature. it will withstand severe punishment from a blunt object; however any pointed object will break the glass instantly and then glass, will crumble into many , very small pieces. Typical application, include a car's side and back windows, sliding glass doors, and entrance doors.

Q?  What is the R value?


R value is a measurement of heat resistance (the higher, the better). R value = the number 1 divided by the U value.

Q?  What is the U factor?


U factor or U value is a measurement of heat transmission. The U value of a window is measured by the number of BTU's That will pass through each square foot of area per degree of temperature difference from one side of the window to the other (the lower, the better). U value = the number 1 divided by the R value. (Department of Energy standards are .30 or lower)

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