In a home of average efficiency, an old sliding glass door can waste more energy year-round than all the walls in that room combined.

Heat is lost during winter and gained during summer as a result of the air leakage and conduction losses through the glass itself.

The discomfort felt when sitting near the door results in a double energy loss. First, the old inefficient patio door wastes energy, as described above. Second, this inefficiency often makes you set the central thermostat higher during winter or lower during summer just to stay comfortable. Each degree you change the thermostat setting can result in greater costs on your utility bills.

There have been tremendous improvements in energy efficiency, security, and styling of replacement patio doors. Some of the new high-tech glass in these doors has an insulation value as high as R-10 in the center of the glass. It has special coatings on the glass surface that reduce heat transfer and block the majority of the sun’s fading ultraviolet rays. This can greatly extend the like-new appearance and actual life of your carpeting and furniture.

From what many homeowners say, the first thing their family notices when a new efficient patio door is installed is the reduced outdoor noise. Noise enters a home through a door by two channels. Much of the noise comes through the glass panes, but a significant amount also comes from air leakage around the frame and seals. Resilient weather-stripping greatly reduces air leakage and multi-pane glass—with heavy inert gas between the panes—blocks sound transmission.

Although any type of efficient door can be installed in place of the old patio door, most people replace an old sliding glass door with either another sliding door or French doors. Each has its advantages, depending on your desired balance between functionality and style. The costs of these two types of doors are not significantly different, and installation time is similar.

Hinged French doors are more stylish and particularly popular today. Hinged doors close on a compression weather-stripping seal, often making French doors more airtight.

Sliding doors rely on noncompression types of weather-stripping. Even though it is not as airtight as a compression seal, it will be better than your existing patio door.

French doors are easy to swing open, but they do require a fairly large open area for clearance. A sliding door just slides in its track, so it requires no open clearance area. Sliding doors also provide a more unobstructed view of the outdoors. There is a little more maintenance on a sliding door to keep its track clean so it glides open and closes easily.

Most door manufacturers allow you to order almost any type of glass you want. The best type for your home depends upon factors such as your climate, orientation to the sun, natural shading, etc. In general, the minimum efficiency level you should select is double-pane glass with a low-emissivity coating and argon gas between the panes.

Even more efficient, but more expensive, is triple-pane glass or double-pane glass with low-emissivity plastic films stretched between them. Selecting optional krypton gas instead of argon gas in the gap between the panes improves efficiency and reduces outdoor sound transmission. This is because krypton gas is denser. Both are inert gases, so they are very stable.

The frame material is also important for efficiency and smooth operation. A pultruded fiberglass frame is very strong and stable. Its strength allows for narrower frame profiles and more glass area. Fiberglass frames can be ordered with a real oak wood veneer on the indoor surfaces. The exterior is painted.

Vinyl door frames reinforced with internal steel supports are good insulators, maintenance-free, and reasonably priced. The corners are fusion welded for extra strength and a clean appearance. Solid wood frames are attractive and strong, but they require regular maintenance. Choosing one with exterior vinyl or aluminum cladding minimizes this maintenance.

The following companies offer efficient patio doors: Champion Window, 800-875-5575; Fibertec, 888-232-4956; Peachtree, 800-732-2499; Simonton, 800-746-6686; and Weathershield, 800-222-2995.

Send inquiries to James Dulley, Michigan Country Lines, 6906 Royalgreen Dr., Cincinnati, OH 45244, or visit dulley.com.