How to Tell If Your Windows Are Energy Efficient

Your windows may be costing you hundreds of dollars a year in wasted energy — and you might not even know it. Here's how to quickly assess whether your windows are performing well or quietly draining your wallet.

On a cold or windy day, hold your hand around the perimeter of a closed window — along the frame edges, corners, and where the sashes meet. If you feel air movement, the seals or weatherstripping have failed. Even a small draft can significantly increase your heating and cooling costs over time.

Close a window on a piece of paper. If you can pull the paper out easily without resistance, the window isn't sealing properly. A well-sealed window should grip the paper firmly. This test works for both single and double-hung windows.

If your windows were installed in the last 15–20 years, check the frame or glass edge for a sticker from the National Fenestration Rating Council (NFRC). This label shows the window's certified performance ratings. The two most important numbers for Arkansas homeowners are:

ENERGY STAR certified windows meet minimum efficiency standards set by the EPA for your climate zone. Arkansas is in Climate Zone 3 (South-Central). If your windows have an ENERGY STAR label, they were certified for your region at the time of installation — though older ENERGY STAR windows may no longer meet current standards, which have been updated several times.

Single-pane windows (one layer of glass) are highly inefficient and should be replaced in virtually all cases. Hold a lit lighter or flashlight near the glass and count the reflections — one reflection means single-pane, two means double-pane, three means triple-pane. If you have single-pane windows, replacement will deliver significant energy savings regardless of other factors.

Fog or moisture trapped between the glass panes of a double- or triple-pane window means the insulating gas seal has failed. A fogged window has lost most of its energy efficiency and cannot be repaired — the window unit must be replaced. This is one of the most common failure modes for windows over 15 years old.

Failed seals, fogged glass, and cracked frames require full replacement. Drafts caused by deteriorated weatherstripping can sometimes be addressed with re-caulking or weatherstripping replacement — a much cheaper fix. However, if your windows are more than 20 years old and showing multiple issues, full replacement is usually more cost-effective than ongoing repairs.