Windows, more than any other standard building item, have seen a significant increase in performance resulting from new technologies such as "low-E" glass coatings and gas-filled windows. These improvements make higher costs palatable, or even economic, when the rest of the home’s heating system is adjusted accordingly.

If the windows are a part of an overall energy strategy that greatly reduces the demand on the heating system, the savings gained in going to a smaller furnace can offset the added cost of the windows, and the on-going energy savings will pay back that extra cost more quickly. However, the most frequent selling point for these high-performance windows is the added comfort over a standard window.