Replacement Windows: Labels, Quotes, and Cheaper Fixes

ENERGY STAR certification is set by climate zone.

ENERGY STAR windows, doors, and skylights must meet requirements for U-factor — how much heat passes through; lower is better — and, where it applies, Solar Heat Gain Coefficient (SHGC), how much of the sun’s heat comes through; lower means less summer heat gain. The current criteria took effect on October 23, 2023. Because the right numbers depend on climate, ENERGY STAR tells shoppers to look for the label that matches where they live.

Separate the product from the installation.

ENERGY STAR advises asking contractors to break a quote down into labor and materials. Certified products may cost more than non-certified ones, but the labor should be comparable, so the breakdown shows what the efficiency upgrade itself costs. Keep the ENERGY STAR and NFRC labels as documentation.

A drafty window is often a leak around the window.

ENERGY STAR describes two quick checks. Close the window on a sheet of paper: if the paper slides easily, the window could seal tighter, often with thicker weather stripping. Or hold a lit incense stick near the seams and sash and watch the smoke; if it is pushed in one direction, you have found a leak.

Signs of leaks around the trim include drafts around a closed window, visible gaps, dust or insects coming in, outside odors, and peeling paint around the frame.

Sealing trim and plastic film cost far less than new units.

Sealing behind window and door trim is a moderate to difficult do-it-yourself project, but ENERGY STAR says the payoff can be substantial even when the windows themselves are airtight — and if you are replacing windows anyway, it is the time to do it. Heat-shrink plastic film over existing windows is rated easy, takes about a day, and costs under $100 in ENERGY STAR’s guide.

ENERGY STAR also notes that window and door leaks usually matter less for energy use than those in the attic and basement. If the goal is a lower bill rather than a better window, the attic air sealing guide is usually the better first project.

Replace for the window’s condition, not only the bill.

• Frames that are rotted, broken, or no longer open and lock safely
• Single-pane glass in a climate with long heating or cooling seasons
• A remodel that is opening the walls anyway

For energy savings alone, compare the quote against the cheaper fixes above and against your actual heating and cooling costs. The federal credit that once covered part of window costs ended for installations after 2025.