At some point, repairs may be too costly or time-consuming and replacement may make more sense. But, before you invest in a complete replacement of all components, consider some less-expensive alternatives:
Replacement window sashes. Older, double-hung windows can have new sashes installed that are multiple-paned and tightly sealed. The window frames remain, and new jamb inserts are installed to accept the somewhat smaller sash units. This approach may not require the removal of interior or exterior trim, and provides an opportunity to seal and insulate all around the unit.
Replacement storm windows and doors. Aging, damaged, or poorly made storm windows and doors can allow air leakage directly onto the main unit, reducing its thermal performance. Replacing the storms can be considerably cheaper than all new windows and can provide good air leak control as well.
Interior window coverings. Although drapes and blinds are important for reducing solar gain during the summer, specially designed interior window coverings are not considered as important for winter energy saving as they were a few years ago. Because they keep much of the warmer room air from the glass surface, condensation from any small air leaks can cause frost build-ups, which can lead to component damage.
What to look for in new windows
Buying windows can be confusing. There are multiple options available, including the materials used in the frames, the finishes, the types and quantities of insulating and sealing materials, coatings, and more. But for evaluating energy efficiency, there are some basic things to look for:
The NFRC label
The first thing you should look for is a label from the National Fenestration Rating Council (NFRC). The NFRC is a nonprofit organization that provides consistent energy and performance ratings of windows, doors, and skylights. It evaluates products according to several categories, including:
U-factor: The ability of a window to conduct heat (the inverse of an R-value, used to evaluate products like insulation). U-factor ratings generally fall between 0.20 and 1.20; the lower the number, the better the energy efficiency of the unit. The recommended U-factor for windows is 0.30 or less.
Solar Heat Gain Coefficient: Measures a window’s ability to reduce heat gain in the summer, thus reducing cooling loads. Based on a zero to 1 scale, a lower number will block more sunlight, reducing solar gain. In Minnesota, a good balance of about 0.50 is recommended.
This guide describes the basic components of a house that separate the outdoors from the indoors. It contains ways to reduce energy use with insulation, air-sealing, windows, and doors. Information is included on how to assess the current operation of your home through an energy audit and how to begin the process of tightening your home to curtail energy consumption.
A significant portion of home energy use is for all of the common things that make our lives easier and safer. The Appliances, Lighting, and Electronics guide discusses options for reducing energy consumption of these devices by changing when and how we use them. Additionally, there is information on what to consider when you are repairing or replacing these items.