What type of windows offers the best insulation?

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Aesthetics are essential when choosing windows for your home, but consumers also want durable, energy-efficient windows. Windows, like virtually all other building materials, has significantly improved in the last few decades.

Windows that insulate

Window manufacturers have several techniques for window insulation. Recently, North America has seen triple glazed windows increase in popularity. An import from Europe, these windows do an excellent job of insulating your home in all types of climates. Glazed glass means a type of glass coated with a glaze that allows in sunlight but reflects heat radiation.  The triple panes serve to provide three layers of glass between the interior and exterior of your home, reducing the burden on your heating and cooling systems.

Triple paned glazed windows increase the amount of insulating space, meaning they work very well in cold winters. They are also a good option for those who live in urban areas because they block noise pollution. The pros and cons to consider:


  • The best window option for canceling noise
  • Better insulation properties than single or double-paned windows


  • Costly and it will take some time to justify the energy savings
  • Some windows may be heavy enough that they require additional support

Double pane glass in windows may be adequate for those who live in temperate climates. To decide which type of windows you need, the pros and cons of double pain glass include:


  • Easy to find, regardless of style and size
  • Available with a wide variety of frame materials
  • A cost-effective option that still provides energy savings.


  • Cracked glass panes are not easy to replace
  • Seals in lower quality windows may crack and eventually fail
  • Double-paned windows do not offer the same energy efficiency as triple pane windows

Framing choices

When choosing windows, insulation properties are an essential consideration. Though most people tend to focus on the glass, energy-efficiency starts with the framing materials used around the windows. Most people tend to choose window framing based on aesthetic qualities, but the framing is where the insulation properties of the window start.

Aluminum or Metal Frames

Aluminum and metal frames have remained popular because they are durable, light, and maintenance-free. However, these materials conduct heat rapidly, making them a poor choice for insulating material.

Some manufacturers are addressing the insulation problem by adding a thermal break, which is an insulating plastic strip. The strip is placed between the inside and the outside of both the frame and the sash.

Adding the thermal break helps to increase the U-factor of the window. The U-factor is the rate at which windows, doors, and skylights conduct non-solar heat flow. Knowing the U-factor of any window is essential when seeking an energy-efficient option.

Fiberglass frames

Frames made of fiberglass usually have air cavities that can be filled with insulation. These air cavities give fiberglass frames superior insulation capabilities when compared to vinyl or wood.

Composite frames

Composite frames consist of composite wood products and are often mixed with polymer plastics. The composites are stable and often have better structural and thermal properties as opposed to conventional wood. They are also moisture and decay-resistant.

Vinyl frames

Vinyl window frames are usually made from PVC with ultraviolet light stabilizers to keep sunlight from destroying the material. Vinyl frames do not require painting, and some come with hollow cavities that can be filled with insulation.

Wood frames

Wood is an excellent natural insulator but requires regular maintenance. Metal clad wood frames can reduce maintenance, but they also reduce thermal performance.

Choosing the right windows for your home

If you have an existing home and wonder if new windows would better insulate your home, consult your utility company about doing an energy audit of your home. A professional will inspect your home and make recommendations about the things you can do to make your home more energy-efficient.

Experts generally agree that single-paned windows, or windows of poor quality, will more than pay for a replacement in saved energy costs. If your windows are damaged, or a safety hazard, replacing them should be an immediate priority.

Choosing the right operational function for your windows

Once you have decided to replace your windows, and you have learned about the insulation value of each option, you still need to decide on the right type of window. The most common options are:

  • Casement—casement windows are hinged on the sides. Hinged windows usually have lower air leakage rates than sliding windows because the sash protrudes from the wall. It can be opened to catch passing breezes, but unfortunately, screens have to be placed on the interior side. Another advantage is that the entire window area can be opened, where sliders are limited to half the window area.
  • Single or double-hung windows—With a single hung window, only the bottom sash slides upward. With a double-hung window, both sashes slide vertically, giving you options on how to catch the best breeze. Double-hung windows do have more air leakage than most other window options.
  • Sliders—You can choose between single or double sliding windows. You can control ventilation from a crack to opening one-half of the glass area.
  • Hopper—Hopper windows are hinged at the bottom. They open inward and have lower air leakage rates than sliding windows. Screens can be placed on the exterior of the window, and similar to casements, the entire window area can be opened.