WINDOWS 101

Sound Control, Gas Fills, and Other Considerations

Final Considerations on Window Selection: This section will discuss a couple of commonly raised topics in residential windows. The Windows 101 section has discussed the main issues of window selection. There are many other topics in residential windows not covered by this section. If you have any specific questions regarding any of the information above, or would like to ask any other specific question, please fill out a request for a Free In-Home Consultation, or call our office.

Sound Control: The acoustical properties of windows are closely tied to infiltration control. Houses with tight, insulated windows are dramatically quiet. The most significant step that can be taken to reduce sound transmission is to minimize air infiltration (see NFRC label). Other than minimizing air infiltration, there are other characteristics that reduce sound transmission: Wider air gaps between glazings. Replacing air with an inert gas, such as argon. A 1/4 inch thick exterior pane, with an interior pane of a different thickness. Triple pane.

Gas Fills: Gas fills, such as argon or krypton, reduce the conductance of the air space between the layers of glazing. This contributes to thermal performance. Remember that the NFRC performance ratings already take into account all the characteristics of a window, including gas fills. One question that often arises is the leakage of gas from a sealed unit. Studies have shown less than 0.5 percent leakage per year in a well designed unit.

Spacers: spacers are often mentioned with great detail by manufacturers trying to distinguish themselves from competition. A discussion of spacers needs to focus on two potential costs of spacers: the rate at which they transfer heat and cold, and their contribution to the durability of the IGU. Both of these factors are already built into the above discussions. As for heat and cold transfer, the NFRC performance ratings already take into account all the characteristics of a window, including the thermal conductance of the spacer. As for a spacers' contribution to durability, that was already taken into account in the IGU accelerated testing.

RESFEN: If you are interested in estimating the energy cost savings for your home due to window and door replacement, you can download a program called RESFEN. The program will require the input of NFRC performance ratings, as well as energy costs for your area. The program can be downloaded for free from http://windows.lbl.gov/software/.