Single Hung Vinyl Replacement Windows

Function

• Single-hung windows often resemble double-hung windows, but the way they function sets them apart. The top portion, or sash, of a single-hung window doesn't move, so only the bottom sash opens. Both sashes open on double-hung windows. Single-hung windows can be more energy efficient than double-hung varieties, because the top sash is sealed and offers one less place for warm or cool air to escape a home in winter or summer.

Vinyl Characteristics

• Vinyl window frames usually consist of polyvinyl chloride (PVC) that's enhanced with ultraviolet stabilizing agents that prevent the PVC from deteriorating in sunlight. The U.S. Department of Energy (DOE) lists vinyl as a good window insulator because it's a poor heat conductor. Therefore, vinyl stays cooler in summer and warmer in winter than metal and other window-frame materials. Unlike wood, vinyl also is resistant to damage from moisture and insects.

Window Panes

• A single pane is usually a poor insulator for any type of replacement window. That's why single-hung vinyl windows with double panes will probably do more to reduce your energy costs. A single pane generally has a "U" factor rating of 1, and a double pane has a rating of about 0.5, according to GreenBuildingAdvisor.com. The "U" factor is the rate at which heat passes through a window, and windows with a lower rating are more energy efficient.

Low-E Coatings

• A single-hung window with a Low-emissivity (Low-E) coating on its panes that fits your climate can maximize a vinyl replacement window's energy efficiency. Low-E coatings control the flow of the sun's heat into and out of a home. For example, the DOE indicates you can reduce the solar heat that enters your home in a hot climate by choosing double-pane windows with a Low-E coating applied to the outside pane. The coating should be on the inside pane to retain solar heat inside your home if you live in a colder climate.

Costs

• Single-hung windows are usually cheaper than double-hung windows, but adding panes and low-E coatings to any replacement window to increase energy efficiency also will increase your costs. Entry-level vinyl windows cost $135 to $200 each at the time of publication, while top-quality varieties ran as high as $800 per window, according to CostOwl.com; windows with wood frames were somewhat costlier, starting in the $400 range and running as high as $1,200 each.