SAVING ENERGY WITH LOW-E GLASS

No other single component of a house affects comfort and energy consumption as much as windows. Per square foot, your windows lose more heat in winter and gain more heat in summer than either your walls or roof.

When it comes to saving Energy & Money, here’s what you need to know. . .

Ice, snow, wind, rain, heat & humidity. Montreal gets some of the toughest, most extreme weather conditions imaginable! All the more reason to think carefully about the choice of windows for your home.

Especially since they can account for up to 30 percent of the year-round energy consumed in a typical house.

To help make your home energy-efficient, Martin Industries uses the latest and best options in technology for saving energy. These include LOW-E, Argon gas, the most advanced weather stripping techniques and more.

For example, switching from single-pane windows or damaged sashes to double-glazed, Low-E windows with insulating sashes will improve comfort substantially. In addition, energy-efficient windows save heat when it is cold, protect furnishings from fading, reduce infiltration of outside air, keep out unwanted noise, allow in fresh air, and prevent glare. Imagine, all that in one window!

Window Basics

During the heating season, there is a large temperature difference between the inside air and the outside air. Cool air descends and hot air rises. If a window is cold while the interior air is warm, there is a tendency for the window glass to cool the air adjacent to it. As warm air hits a window surface that is cool, the warm air is cooled and drops toward the floor, causing drafts.
During the cooling season, although the outside air temperature feels hot at 90°F and above, the differences between outside air temperature, inside air temperature, and body temperature are much smaller. This slows air movement, so drafts are much less noticeable.

What many people perceive as a draft, is a combination of the cool air falling downward and the heat loss by thermal radiation from their warm skin to the cold glass surface. (Remember that for single-pane windows, the inside surface of the glass is closer to the outdoor temperature than to the indoor temperature.)

Condensation can also be a problem on single-pane windows when the outside air temperature is low and indoor temperature and humidity are high.
Condensation appearing between the panes of insulated glass indicates a failed seal and requires replacement of the insulated glazing, or the whole window, depending on the window design. Insulation reduces heat transfer by creating dead air space. Still air is a poor conductor of temperature, so the more still air that is trapped, the slower the transfer. While a thin layer of still air on the surface of a single-pane window provides insulating value, multiple-pane windows trap relatively large volumes of still air, significantly increasing the insulating value.

High-Tech Options

Energy-efficient windows use a variety of technologies to reduce conduction, convection, and radiation, and to absorb or reflect the sunlight which is part of the radiation. The most effective technologies available for residential windows include multiple glazings, insulated frame materials and designs, spacer technology, LOW-E and solar-control coatings, insulating spaces filled with inert gasses, and reducing air leakage. Martin Industries offers all these options.

Multiple Glazing, Frame Design, and Spacers

In earlier versions of thermal-pane (or double-pane) windows, the temperature difference often resulted in condensation. Moisture collected where the frame met the wallboard, and it stained and deteriorated the drywall and surrounding areas, or worse. A substantial amount of infiltration then entered the home through and around the deteriorated window framing and closures.

The simple double-pane, aluminum-framed windows sold today typically have a thermal break to reduce condensation problems . Moving away from metal frames to wood, vinyl or composites and adding insulation has greatly reduced the heat transfer through the frame, as well as improving the windows’ appearance.

The spacer is the small piece of material separating the panes of glass. It affects how much heat is transmitted between the panes. Improved spacer technology and better construction and sealing methods are also factors in the higher performance of modern windows. Spacers do most of the flexing instead of the sealant during temperature changes. This resists sealant failure.

Low-E Technology and Insulating Gasses

Low-E technology, are a big improvement over single-pane, double-pane, or conventionally tinted windows, and the extra cost is now minimal.

Low-E glass contains a microscopically thin, transparent layer of metal or metallic oxide applied to the interior face of a multi glazed window, or a thin plastic film placed between the panes. The best of these coatings consist of a soft layer that must be protected from handling and abrasion. These coatings act as radiant barriers.

A gas (typically argon, krypton, or xenon) is often used instead of air between the panes to further improve the insulating value. Argon is relatively cheap and plentiful and is less conductive than air. Krypton is more effective than argon but significantly more expensive. Xenon would be better still, but it’s even rarer and more costly.

Air Leakage Operable windows are popular for ventilation, but unintentional air leaks may account for up to 10% of the energy use in a home. For example, wind pressure can flex the window unit and increase air flow, and sliding windows with weather stripping do not provide as tight a closure as windows with compressing seals.

About Doors

Exterior doors don’t offer as much energy-saving opportunity as windows, mostly because of their relatively small total area. However, a very loose or badly weather-stripped door not only wastes energy but causes uncomfortable drafts.