Energy saving windows are constructed in such a way so as to improve their all around efficiency. Different features will have different benefits and applications depending on your location and climate. Many of these features are becoming standard issue in energy saving windows. These different construction options and features can help drastically improve the efficiency of your window and save you money in the long run.
The first place to start with energy saving windows is their construction. The quality of the construction of a window is going to have a large effect on how efficient it ends up being. All the Low-E coatings and glass panes in the world do not mean much if the window leaks in a poor fashion. The best way to judge the quality of the construction of your window is to inspect the seams, joints, and hardware that was used. Interlocking or overlapping seams and joints are much more resistance to air penetration than those that are flush. If the hardware is cheaply constructed and generic, it is not likely that the manufacturer did a much better job on the rest of the piece. This should be used as a guideline to determining how well built the product actually is.
The next major hardware feature for the window will be the style of panes you choose for the window. Double or triple-paned glass windows always perform more efficiently than a single given like circumstances. A double-paned window features great efficiency because it works to prevent radiant energy transfer from the exterior to interior, and vice versa. That means you will see a drop in heating and cooling costs in their respective seasons. These are efficient windows; but the most efficient you will run across is triple-pane. These actually add two more insulating layers in the form of another layer of glass and inert gas on the interior. Triple-paned windows work well in a variety of climates but extreme temperatures will garner the most efficient use out of them.
The insulating qualities of an inert gas filling allow a window to increase its efficiency drastically. When radiant energy strikes the glass, the glass begins to absorb the energy. Once it reaches the point where it can no longer absorb energy, it begins to let the radiant energy through. An inert gas filling between the window panes prevents the radiant energy from transferring from a pane to the next pane in the series. A properly sealed inert gas filled double-paned window can offer near the same insulating qualities that some walls can. For any environment where maintaining a temperature or keeping extreme temperatures out is necessary; inert gas filling between window panes is a leading insulator.
Another major hardware feature are Low-E coatings. These coatings are designed to help reflect energy on its respective side back out. On the inside, it will help keep cooling and heating in. On the outside, it will serve to deflect much of the energy that is striking the window. It accomplishes this as it is made of metal flakes that are bonded onto the glass during production. The three primary coating types are Low-E, Low-E2, and Low-E3. Each is more efficient than the last though it should be noted that they do suffer from diminishing returns. The further coats are still benefiting you but they do so in different ways from the earlier coats. Low-E3 coating offers about the same performance in winter that Low-E coats do. But during summer, the Low-E3 coating provides incredible gains in performance.
The last major point to note is that of seals and weather-stripping. All of the prior hardware points are useless without effective control of the seams of the window unit. Bad seals can cause an incredible amount of problems with the windows as they permit the easy transfer of air and moisture through them. That transfer can permit mold and rot to take place on the wooden framing. A ruined seal will cause an increase in heating and cooling bills with the addition of losing comfort in the home. Any problems with seals should be addressed immediately. Poor quality of seals or weather-stripping on a product should be an immediate red flag.