Types of Window
Common types of windows are fixed, single-hung, double-hung, casement and sliding. Choices among these types are most likely determined based on architectural design, space availability and ease of access. From an energy efficiency perspective, these windows, because of the way they operate, have relatively different air leakage properties. Fixed windows show little or no air leakage. Casement windows can be made to allow little leakage. Single-hung, double-hung and sliding windows tend to allow more air leakage than the other two types.
Window Rating
The National Fenestration Rating Council (NFRC) rates the performance of many windows according to the five properties described above. The rated windows will carry an NFRC label (see example in picture). These ratings show the overall performance taking into consideration of the glass, coating, frame material and construction. Use the NFRC ratings to choose the right window for the right room and to compare different products. More details about the NFRC rating can be found here.
Installation
The best windows cannot perform well unless they are installed correctly – leaving no air gaps, flashed properly to avoid water damage. Make sure to hire a good installer or follow instructions meticulously if doing it yourself.
