This is a new technology that allows the operator to control how much light passes through the window at just the touch of a button, flip of a switch, or turn of a knob. Smart window technology also doesn’t need any window treatments such as blinds and curtains.

Several technologies can be used in smart windows: thermotropics, photochromics or photochromatics, liquid crystals, suspended particle displays, electrochromics, and reflective hydrides.

Thermotropics: this is the same technology that is used in mood rings. It is highly sensitive crystals that react to changes in temperature. It isn’t the most practical option for smart windows.

Photochromics: eyeglasses that change according to the light use this technology. The molecules that make this material don’t react to artificial light, but they change shape when exposed to UV light. Obviously this wouldn’t be great for smart windows either. It would react the same for a cool winter light as it would for hot summer sun. This isn’t the most efficient use of windows in the winter.

Liquid Crystals: calculators, watches, and digital clocks use liquid crystal displays (LCDs). LCD smart windows are translucent when an electrical charge is absent.

Suspended Particle Displays: SPDs are sandwiched between two layers of glass or plastic. Those layers are then coated with a transparent conductive material. When electricity reaches the SPDs through the conductive material they line up and allow light to pass through the window. If only some light is wanted, but not all, a lower voltage is applied to the conductive material.

Electrochromic: these smart windows are almost exactly opposite to SPD windows. They are transparent when no electrical charge is applied to it. However, like SPDs, electrochromic windows can be adjusted according to the desired amount of light. Only enough electricity is required for electrochromic windows to change its shade; it doesn’t need a constant charge to maintain the desired shade. That makes this type of smart window very efficient.

Thumbnails of liquid crystal, SPD, and eletrochromic windows.

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Single-glazed, double-glazed, and triple-glazed windows are all options.

Single-glazed windows: These are best for places like garages and sheds that need minimal insulation.

Double-glazed windows: These are windows with two panes of glass with air or (more commonly) a colorless, odorless gas, usually argon or krypton. This can get an R-value of R5 when the glass is treated with a low-emittance (Low-E) coating.

Triple-glazed windows: This is pretty much like double-glazed windows except the gas is sandwiched between three panes of glass. This is a very efficient option achieving an R-value up to R10!

Here are a couple of sources that show how to glaze windows on your own:

• http://www.ehow.com/how_2054616_glaze-window.html
• YouTube video (not great quality, but it shows how to do it more or less)

(Source: This one has many more glazing options than I went into here.) (Source)

Several materials are used to make window frames: Wood (including vinyl-clad), aluminum, vinyl, and fiberglass. Wood and hollow vinyl being the most common.

Wood: These are typically the most expensive frames. They can be either solid wood, vinyl-, or aluminum-clad. The big drawback to solid wood is the frequent maintenance it requires. Vinyl- and aluminum-clad frames are by far the most popular. They require much less maintenance than solid wood, but the exterior color cannot be changed without replacement.

Vinyl: Vinyl frames are everything that solid wood frames aren’t: rot-proof, weather-proof, and insect-proof. However, these, like the wood-clads, have aesthetic drawbacks. Over time vinyl frames fade. They also move a lot, but they are built with that in mind.

Fiberglass: These frames are more expensive than vinyl, and they have the same u-value. It also must be painted. Fiberglass frames are relatively new to the market.

Aluminum: Aluminum frames are not efficient at all! Though they are the third most widely-used window frame today, they are a very distant third, claiming only 17% of new home window frames. On the flip side, they are every durable and require very little maintenance. Still, it’s probably best to stay away from these, if you have a choice.

U-factors:

• Aluminum: 1.0-2.2
• Aluminum-clad wood: 0.4-0.6
• Wood and vinyl: 0.3-0.5
• Fiberglass: 0.2-0.3

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Replacement windows, repair windows, window frames, window sashes, window glazes, smart windows! R-value, U-factor! AHHH! The mystery of it all is overwhelming, so let’s dispel some of it.

Well, first things first: the difference between R-value and U-factor. As we have seen elsewhere, the higher the R-value the more efficient it is; the U-factor is the opposite. The lower the U-factor, the greater the window’s resistance to heat flow, thereby making it more efficient.

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Replacement: Probably, you will only want to replace the entire window (frame, sash, and glass) if there has been water damage. Then you must determine and fix the point of that water damage. This is the most expensive method, considering labor. This will, however, give you more options than repairing, and is the most durable and energy-efficient.

Repairing: This is different than replacing the entire window. Perhaps the only thing that’s wrong with the window is that the sash or seal has started leaking. Or maybe you just want to upgrade your window’s efficiency without getting too involved.

• Replacing the sash: This repair method is easy and relatively cheap, and comes with the bonus of being an energy-efficient upgrade. However, it may be hard to fit a new sash in an old opening.
• Replacing sash and frame: This option is even more efficient than replacing just the sash because the sash and frame have been tested as an entire unit. This has a couple of cons though: it is the most expensive materially than either replacing the sash or the entire window, and it has a bulkier look because of an additional window frame.

That gets the most basic methods of repair/replacement windows. We’ll take a look at some of the materials later. (Source)