Signs You Need New Windows

Windows rarely fail all at once, so the signs are usually comfort and energy problems that build over time. ENERGY STAR describes older single-pane and clear-glass double-pane windows as drafty, cold to sit next to, and prone to winter condensation and frost. NFRC ratings on the window label help you judge how leaky or heat-prone a window is. Read the signals below against your own windows.

Drafts and air leakage

A window you can feel air moving through is leaking conditioned air. ENERGY STAR notes that older single-pane and clear-glass double-pane windows can be drafty and feel cold when you sit next to them, and it points to windows with air leaks or drafts and degraded sills and sashes as sources of discomfort when it is cold and windy out.

The NFRC label quantifies this with an air leakage rating. ENERGY STAR explains that air leakage measures the rate at which air passes through joints in the window, in cubic feet per minute per square foot, and that lower values mean tighter sealing, with industry standards typically requiring 0.3 or better.

Condensation and frost in winter

Moisture forming on the inside of glass is a sign the window surface is running cold. ENERGY STAR states that older single-pane and clear-glass double-pane windows get condensation and even frost build-up in winter.

This happens because a poorly insulating window lets the interior glass surface drop near the outdoor temperature. Persistent condensation and frost point to weak insulating performance and, over time, can damage sills and sashes.

High energy bills and single-pane glass

If your home has single-pane windows, they are a likely driver of high bills. ENERGY STAR calls single-pane windows poor performers at insulating against cold weather and characterizes them as big energy wasters.

The upside of replacing them is measurable. ENERGY STAR reports that certified windows lower household energy bills by an average of up to 13 percent nationwide when they replace single-pane windows, which is the clearest sign that aging glass is costing you money.

Summer heat gain and fading

Rooms that overheat in summer and furnishings that fade point to glass that lets in too much solar energy. ENERGY STAR notes that standard double-pane windows allow approximately 75 percent of the sun's heat into a home, and that single-pane windows typically lack coatings to block solar heat in summer, which increases air conditioning costs.

Certified windows address both problems with special coatings. ENERGY STAR states those coatings reduce fading of valuables and furnishings by up to 75 percent, so noticeable fading and hot rooms are signals worth acting on.