As expected, the costs of residential windows vary with the type, size and features such as weatherstripping, glazing, frames and edge spacers.
There isn’t an average cost. That’s too abstract and unmeaningful. Window prices range anywhere from $100 to $2,000 or more. At least we should distinguish between single, double and triple glazing windows; or between Energy Star and non-Energy Star products; or take into account the materials used in their manufacturing: fiberglass, aluminum, vinyl, wood, aluminum clad wood windows.
Single-pane window prices
Single-pane windows are a thing of the past. Their price was low… but they are very energy-inefficient and a cause of high energy bills. Comfort requires other types of windows.
Energy Star windows prices
Energy Star (American) windows are more expensive than non-Energy Star windows. Expect at least $10 or $20 more per square foot…
Typically, Energy Star windows worth the price, when compared with windows that do not meet the Energy Star standards. They provide energy savings and comfort.
But be aware. Energy Star standards are lax when compared to PassiveHaus and other more demanding standards. Obviously, the prices of windows meeting the highest energy standards (high quality triple-glazed windows, foam-filled fiberglass windows) are a lot higher, as mentioned below.
Prices of double-Glazed windows
The costs of double-glazed windows vary a lot, depending on many features.
A wood double-glazed 4- by 6-footer with fixed center pane and 2 openable casements, can cost up to, say, $600. An Energy Star JELD-WEN 36-in x 60-in Vinyl Double Pane Double Strength New Construction Casement Window will cost you about $400 (in large retailers).
But there are much cheaper windows, especially when purchased in large home improvement stores.
Be aware, anyway. The most important is not the brand, or even the Energy Star label. The most important is the specifications of the windows, especially those expressed in their energy coefficients: U-factor (insulation), Solar Heat Gains coefficient (SHGC), Air Leakage (AL)... These coefficients should respond to your needs, your climate, or the walls where the windows are going to be installed. See: The best windows for cold, mixed and hot climates.
Cost of triple-Glazed windows
The prices of German windows for Passive Houses (high quality triple-glazed windows, with special multiple weatherstrips, meeting the highest energy efficient standards) can cost about $90-$100 per square foot or more (plus 5-10% more for shipping, when imported).
But there are less expensive triple-glazed windows. Canadian triple-glazed fiberglass windows may cost $40 - $50 a square foot, which is a lot less. And you can also purchase high-quality triple-glazed windows from Polonia and other central European countries at prices closer to those of Canadian manufacturers.
Many energy experts are of the opinion that narrow fiberglass frame windows with lots of foam inside, provide very good window frame; and since manufacturers are using the same glazing and the same edge-spacers, many of the alternatives to the German PassiveHaus windows can be as good as the best German windows.
Note: economies of scale (associated to Zero Energy Buildings and to a wider use of high-performance windows) can lower prices of triple-glazed products significantly.
Cost of vinyl, fiberglass, aluminum, wood, aluminum-clad windows
Vinyl (PVC) windows are increasingly popular, and are much more affordable than wood or fiberglass windows.
Aluminum windows tend to be the most inexpensive, followed by vinyl, fiberglass, and wood, in that order. But this is a very broad rule. The quality and price of fiberglass and vinyl (or wood) varies a lot, and there are many details involving the windows that should be carefully considered.
You can purchase a low-end window of a certain type (fiberglass, for instance) for about the same price as a high-end window of another less expensive type (vinyl, for instance).
Basing your buying decision on the price alone is a bad idea. The least expensive type of windows (aluminum windows) are falling out of fashion in residential buildings; aluminum allows very strong windows, but vinyl is much more energy-efficient, and also inexpensive.
See, for details: Aluminum vs. Wood vs. Fiberglass vs. Vinyl vs. Clad Frame Windows
Prices of windows in big home improvement retailers (Home Depot, Lowes)
You can find very affordable windows in big home improvement retailers; but be aware: most of the windows sold in large retailers are of low quality. Typically they do not sell windows meeting very high-energy standards.
And do not forget: buying inexpensive energy-inefficient windows is a big mistake. You will increase your energy bills, and you will lose out on home’s comfort.
Window manufacturers and prices
The offer of the leading window manufacturers varies a lot. That’s not just a price policy issue. Comparing their prices it’s often like comparing apples to oranges; it simply doesn’t make sense.
We should make sure that the comparison is realistic, such as comparing high-end windows with other high-end windows (the high-quality fiberglass Canadian windows with the German PassiveHaus windows mentioned earlier, for instance).
Is it worth to buy expensive windows?
Windows are a key element for comfort and energy savings. Inexpensive energy-inefficienty windows will compromise the thermal performance and the comfort of any building.
But do not forget the basics. High efficient windows should be part of a larger energy-efficient strategy, involving super-insulated and very air-tight buildings.
Installing expensive high-quality windows in leaky and poorly insulated homes will not be of great help.
Windows can provide very significant energy savings (besides comfort). But they are just a part of a large set of building components. Their payback can be very short or very long, depending on the other elements and climate issues (and the type of building: single family homes, apartments, offices… other buildings).
In a reasonably insulated apartment (with a small amount of wall surface, protected by other apartments), replacing low-energy efficient windows with high energy-efficient windows can involve a short payback period. Energy savings can be very significant.
In a well insulated and airtight home, expensive high-performance windows can also have a short payback (in new construction).
Otherwise, the payback period will be long. As mentioned, it isn’t worth to install top quality windows in leaky and insulated homes. And we should also consider elements like the size of the windows, the design and solar orientation of the building, and climate issues.
If your home has good sealing and insulation levels on its walls, ceilings and floors, your old and energy-inefficient windows are very probably the biggest source of energy loss and unwanted heat gains. And it’s not difficult to figure out that their replacement is a rewarding investment, if your heating and cooling costs are high.
But, that's not the case in many other situations. In leaky and poorly insulated homes, new windows may block some drafts and air leakage, and reduce unwanted heat loss (or heat gains), but will not increase the overall energy efficiency of the buildings.
People often feel disappointed with their new windows, when they do not solve condensation and other thermal problems; but that is explained by other factors (or by cheap replacement windows that do not add much to the old units).
The best windows for cold, mixed and hot climates
Casement Windows Energy Efficiency
Sliding Windows Energy Efficiency
Aluminum vs Vinyl vs Fiberglass vs Wood vs Clad window Frames and Sashes
Top Double and Triple Pane Window Manufacturers
The National Fenestration Rating Council (NFRC)
House-energy video on residential windows: