Constructive Choices
By: Dmitry Koukhtenkov
In today’s marketplace it’s hard for the average consumer to make a decision about which windows they should purchase. Part of the reason for this is the lack of knowledge about different options and framing materials that are available. In this section we will examine the most popular frame materials currently available, including: Aluminum, Wood, Vinyl(PVC), Combination/Clad windows, and Fiberglass. We'll describe the characteristics and benefits of each frame. Particular attention will be given to the energy efficiency aspects of window frames. Window frames do more than simply hold the glass in the wall. Their material, finish, and style help to define the architectural character of the home. The frame allows us to open the window and bring in fresh air, it also should resist rain and wind and help prevent heat loss.
When comparing windows, buyers should consider several aspects including: energy efficiency, cost, security, maintenance, ease of cleaning, aesthetic appeal, color selection, durability and ease of use. Knowledge of your window frame options is essential to understanding the function and benefits of high performance windows.
In the first section we will be discussing Aluminum Window Frames:
Aluminum Frames
When double glazing first became a popular window choice in the 1960s, a high percentage of window frames were made of aluminum. Aluminum remained the popular choice for framing double glazed windows through the mid-1980s, when it held over 60% of the market. Since the introduction of new framing materials (PVC, Fiberglass), the market share of aluminum framed windows has dropped steadily. As of 2003, less than 17% of windows sold were aluminum framed. There are many reasons for the drop in popularity - and still some good reasons for choosing aluminum.
The early popularity of aluminum was based on price and convenience. Aluminum was very competitive with wood, the only other choice for window frames in the early years of double glazing. In addition, aluminum is easily extruded in the shapes and lengths needed to frame windows of any shape or size. It's strong, durable and very close to maintenance free.
Design of the aluminum extrusions is critical to energy performance and the structural/operational characteristics of the window product. Dies are created for extrusion of each of the several different shapes that may occur in a single window. Extrusion design requires a delicate balance; larger, more complex extrusions may make a stronger frame but detract from the energy performance and increase production cost.
Aluminum can be fabricated to extremely close tolerances. This, coupled with the material's durability and strength, insures that an aluminum window will provide years of reliable operation.
Aluminum frames do have one significant drawback, however. Aluminum is an excellent conductor of heat and cold. It's such a good conductor, in fact, that in colder temperatures, frost often forms on interior surfaces of the windows close to the aluminum joints. The end result is windows that are significantly less efficient in terms of heat and energy than those framed in other materials. It is about 1 000 times more conductive than materials like wood, vinyl or fiberglass. However, aluminum window frames are often designed using a lower profile cross-section than their counterparts. This smaller surface exposure can help minimize frame heat loss and yield a larger glass vision area
Thermally improved frames are the best of aluminum frames. A "thermally-improved" frame decreases heat loss and improves energy efficiency by the addition of a non-conductive material between the aluminum's on the interior and exterior of the window. This addition is known as a "thermal break" Thermally improved aluminum frames perform better than standard aluminum frames. Aluminum framed windows should be considered only with a thermal break. The thermal break in aluminum windows is usually a strip of rubber or plastic, placed between the inner and outer frame. The thermal break lowers the ability of air to pass through the aluminum. Without the thermal break, the window will be highly conductive, and hence not very energy efficient.
Aluminum framed windows are now mostly restricted to commercial applications. Low values in energy efficiency do not render well in general application, except perhaps in temperate climates. For instance in Canada, it will be difficult for aluminum windows to pass building code, without going to triple glazed units. In comparison to other window types (PVC, Fiberglass) that can meet the same types of efficiency ratings with double glazed units.
In our next post we will review Wood as a Framing Material for Windows.
In today’s marketplace it’s hard for the average consumer to make a decision about which windows they should purchase. Part of the reason for this is the lack of knowledge about different options and framing materials that are available. In this section we will examine the most popular frame materials currently available, including: Aluminum, Wood, Vinyl(PVC), Combination/Clad windows, and Fiberglass. We'll describe the characteristics and benefits of each frame. Particular attention will be given to the energy efficiency aspects of window frames. Window frames do more than simply hold the glass in the wall. Their material, finish, and style help to define the architectural character of the home. The frame allows us to open the window and bring in fresh air, it also should resist rain and wind and help prevent heat loss.
When comparing windows, buyers should consider several aspects including: energy efficiency, cost, security, maintenance, ease of cleaning, aesthetic appeal, color selection, durability and ease of use. Knowledge of your window frame options is essential to understanding the function and benefits of high performance windows.
In the first section we will be discussing Aluminum Window Frames:
Aluminum Frames
When double glazing first became a popular window choice in the 1960s, a high percentage of window frames were made of aluminum. Aluminum remained the popular choice for framing double glazed windows through the mid-1980s, when it held over 60% of the market. Since the introduction of new framing materials (PVC, Fiberglass), the market share of aluminum framed windows has dropped steadily. As of 2003, less than 17% of windows sold were aluminum framed. There are many reasons for the drop in popularity - and still some good reasons for choosing aluminum.
The early popularity of aluminum was based on price and convenience. Aluminum was very competitive with wood, the only other choice for window frames in the early years of double glazing. In addition, aluminum is easily extruded in the shapes and lengths needed to frame windows of any shape or size. It's strong, durable and very close to maintenance free.
Design of the aluminum extrusions is critical to energy performance and the structural/operational characteristics of the window product. Dies are created for extrusion of each of the several different shapes that may occur in a single window. Extrusion design requires a delicate balance; larger, more complex extrusions may make a stronger frame but detract from the energy performance and increase production cost.
Aluminum can be fabricated to extremely close tolerances. This, coupled with the material's durability and strength, insures that an aluminum window will provide years of reliable operation.
Aluminum frames do have one significant drawback, however. Aluminum is an excellent conductor of heat and cold. It's such a good conductor, in fact, that in colder temperatures, frost often forms on interior surfaces of the windows close to the aluminum joints. The end result is windows that are significantly less efficient in terms of heat and energy than those framed in other materials. It is about 1 000 times more conductive than materials like wood, vinyl or fiberglass. However, aluminum window frames are often designed using a lower profile cross-section than their counterparts. This smaller surface exposure can help minimize frame heat loss and yield a larger glass vision area
Thermally improved frames are the best of aluminum frames. A "thermally-improved" frame decreases heat loss and improves energy efficiency by the addition of a non-conductive material between the aluminum's on the interior and exterior of the window. This addition is known as a "thermal break" Thermally improved aluminum frames perform better than standard aluminum frames. Aluminum framed windows should be considered only with a thermal break. The thermal break in aluminum windows is usually a strip of rubber or plastic, placed between the inner and outer frame. The thermal break lowers the ability of air to pass through the aluminum. Without the thermal break, the window will be highly conductive, and hence not very energy efficient.
Aluminum framed windows are now mostly restricted to commercial applications. Low values in energy efficiency do not render well in general application, except perhaps in temperate climates. For instance in Canada, it will be difficult for aluminum windows to pass building code, without going to triple glazed units. In comparison to other window types (PVC, Fiberglass) that can meet the same types of efficiency ratings with double glazed units.
In our next post we will review Wood as a Framing Material for Windows.
posted by Brokicki at
11:38 AM
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