Vinyl vs. wood or aluminum
Vinyl is a better insulator than wood or aluminum. It doesn't conduct heat or cold like aluminum - a major source of lost heating/cooling energy. And, it doesn't swell and shrink like wood when temperatures change. It never needs painting and won't show scratches, unlike aluminum or wood windows.
> Today, over 75% of replacement windows are vinyl*. But just because a window is made of vinyl doesn't mean it is a superior product. The design, engineering and manufacturing of the window all help distinguish a poor window from a superior window.
> *Sabre Report 2004.
The thing to remember when considering an R-value is that the higher the R-value number is, the greater the insulation value. As with any measure of energy efficiency, it's not so much what's considered acceptable, as what is acceptable to you. Insulation in the sash and/or mainframe of a vinyl window can significantly up the R-value of a window frame. Check for the availability of this feature when assessing a window's energy efficiency.
Glass is rated in R-values also - the same used to rate window frames. The type of glass, thickness, number of panes, distance between the panes, as well as, the manner in which panes are connected, all affect the R-value performance of the window.
This is a standard measure of heat transfer through an entire window unit. The methods for measuring U-factor ratings were developed by the National Fenestration Rating Council (NFRC) at the request of the U.S. Department of Energy and the Federal Trade Commission.
The lower the U-factor the better the window's insulating ability. A window's U-factor is the reciprocal of its R-factor. They both measure its insulating ability. Look for windows with low U-factors and high R-values.
There are two major types of Low-E (the ‘E' stands for emissivity) glass: hard-coat (pyrolitic) and vacuum-deposition (sputter). Both types block radiant heat, keeping summer's heat outside and winter's heat inside. And both block the sun's rays to some degree.
But windows made with multi-layer, vacuum deposition (sputter coat) Low-E glass have much better visual clarity. With this type of glass you have very little haze factor which provides almost the same clarity as clear ‘uncoated' glass.
Argon or Krypton gas
Air between the panes of insulating gas can be replaced with high-density Argon or Krypton gas. This process provides windows with a both increased energy efficiency and increasing sound deadening properties. Both Argon and Krypton are safe, odorless, colorless gases that occur naturally in our atmosphere. But, because of their density, heat and cold do not pass through these gases as easily as through air. When Argon or Krypton gas is used in an insulated glass system with a vacuum deposition (sputter) coat Low E glass, it creates one of the most energy efficient windows you can buy.
Some of the same features that make a window more energy efficient can also help to significantly cut down on noise transmission from outdoors.
Wood grain finishes
Today's better interior wood grain finishes are designed for a lifetime of maintenance-free beauty. They've proven themselves over time to resist fading, chipping, peeling and blistering.