It's about cost
Below are national averages for installing ten double-hung windows measuring 3-by-5 feet, including installation, according to Remodeling magazine's 2009-10 "Cost vs. Value Report." All windows are double-paned with inert gas between the layers (for regional breakouts, go to the Cost vs. Value Report).
Midrange vinyl: Vinyl frame. Midrange wood: Wood frame; exterior clad in vinyl or aluminum. Upscale vinyl: Simulated mullions and wood-grain interior; custom-color exterior; low-E coated glass. Upscale wood: Simulated mullions; hardwood interior; custom-color, aluminum-clad exterior; low-E glass.
What's the payback?
Midrange vinyl: $10,728 (cost); $8,217 (resale)
Midrange wood: $11,700 (cost); $9,044 (resale)
Upscale vinyl: $13,862 (cost); $10,601 (resale)
Upscale wood: $17,816 (cost); $12,738 (resale)
Source: Remodeling magazine "Cost vs. Value Report," 2009-10.
It's about energy efficiency
To make an apples-to-apples comparison of the energy efficiency of all types of windows, regardless of differing components, you need to know two critical ratios:
U-factor. The lower the number -- the range is usually 0.25 to 1.25 -- the better the window insulates and the greater the energy savings it will produce in climates where heating dominates home-energy bills.
Solar heat gain coefficient. The lower the SHGC (typically 0.25 to 0.80), the better the window blocks heat caused by sunlight and the greater the savings in climates where cooling dominates.
Energy Star-qualified windows are labeled to indicate to which of four U.S. climate zones (northern, north central, south central and southern) a window is best suited, based on its U-factor and SHGC, which are also shown.
It's about materials
Cost is for a 3-by-5-foot, double-hung unit, excluding installation.
Vinyl ($200 to $800)
They provide good insulation (especially when air cavities in frame are filled) and are moisture-resistant. Better-quality vinyl windows are more dimensionally stable -- they swell and shrink less with extremes of temperature -- and resist yellowing, cracking and warping. Cons: Colors and textures may be limited. Look for paintable or stainable surface treatments and hybrids with interior, wood-veneer finishes.
Composite ($600 to $1,000)
Pros: Made of wood and polymer, which resembles wood in terms of strength and insulating value but resists moisture and decay better. May be textured, stained or painted. Cons: None.
Fiberglass ($750 to $1,200)
Pros: Strong, durable and dimensionally stable; may be painted or made to simulate wood. When air cavities are filled, insulating value is similar to wood and insulated vinyl. Cons: Few manufacturers.
Wood and clad wood ($800 to $1,500)
Pros: Dimensionally stable, naturally insulating and aesthetically appealing. Cons: Susceptible to moisture and insect damage. Look for treatments designed to increase durability and reduce maintenance, including exterior metal or vinyl cladding.