Drafty Windows: Repair, Weatherize or Replace?

Hold your hand near a window on a windy January night and you’ll feel it. The Department of Energy says about 30% of a home’s heating energy is lost through windows. That’s the number window salespeople lead with. What they tend to leave out is how much of that you can fix without buying a single new window.

Take a 1950s house with its original wood windows and a front bedroom that never feels warm. The first quote is for new windows throughout. Before signing, the owners spend a Saturday with caulk and V-strip weatherstripping and adjust the sash locks so each window closes tight, and the draft in that bedroom mostly disappears. Two windows really do have soft, rotted sills, and those get replaced. The rest get storm windows.

First, find out where the cold is coming from

On a windy day, hold a lit incense stick or a strip of tissue near the edges of the sash, the frame and the trim. If the smoke streams sideways, air is leaking. If the glass itself is ice cold but the edges are still, the issue is the glass, which is a different (and more expensive) problem.

Then look at the window’s condition. Soft or crumbling wood on the sill, glass fogged between the panes of a double-pane unit, broken balances that won’t hold the sash up, or a window painted shut: those are reasons to repair or replace that a can of caulk won’t solve.

Tier one: tighten what you have

This is the cheapest work in the house per dollar of comfort, and a handy homeowner can do most of it in an afternoon.

• Caulk the trim. Run paintable caulk where the interior trim meets the wall and the frame, and exterior-grade caulk where the frame meets the siding outside.
• Weatherstrip the sash. Foam or V-strip weatherstripping where the sash meets the frame and where the two sashes of a double-hung window meet in the middle.
• Check the sash lock. On a double-hung window, the lock pulls the two sashes together. If it doesn’t close snugly, adjust or replace it.
• Use window coverings at night. The DOE suggests closing curtains, shades or plastic window film on cold nights to hold heat in.

The DOE’s own advice on new windows is to air seal and insulate the house first. That order matters: sealing the leaks may change whether you need new windows at all.

Tier two: storm windows

If your windows are single-pane but structurally sound, which is common in older and historic houses, a storm window adds a second layer of glass and a second air seal. ENERGY STAR now certifies low-e storm windows, which have a coating that reflects heat back into the room.

ENERGY STAR estimates that adding low-e storm windows over single-pane windows saves about $350 a year on heating and cooling, or roughly 10%, on a national average, and calls that estimate conservative because it leaves out the savings from reduced drafts. It says homeowners typically recover the extra cost of the low-e version in about three years. Storm windows are especially useful in historic districts, where they keep the original windows in place; check local rules first.

Storms aren’t the answer for windows that are rotted, broken or don’t open and close properly. ENERGY STAR recommends replacing those.

Tier three: replacement

Replacement is the right call when the window itself has failed: rot in the frame or sill, fogged glass in a double-pane unit, broken balances, or sashes that won’t open, close or lock. It’s also a fair choice for comfort, noise, ease of cleaning, or a planned sale.

On energy, keep expectations realistic. The Department of Energy says ENERGY STAR windows can save 7% to 15% or more on annual energy bills, depending on where you live and what you’re replacing. That’s meaningful, but at several hundred dollars a window, it isn’t a fast payback by itself.

Insert or full-frame? An insert replacement fits a new window into the existing frame, which This Old House says typically costs less. A full-frame replacement removes the old frame and sometimes trim and framing, which costs more but lets the installer fix rot and seal the opening properly. If the frame is soft, inserts just hide the problem.

How to buy replacement windows

ENERGY STAR’s buying advice is worth following closely:

1. Get at least three quotes.
2. Match the window to your climate. ENERGY STAR divides the country into four climate zones. Ask for each window’s U-factor and solar heat gain coefficient in writing. In the North, lower U-factor matters most; in the South, lower solar heat gain.
3. Put the specs in the contract, including that the windows are ENERGY STAR certified for your climate zone and will arrive with the ENERGY STAR and NFRC labels.
4. Read three warranties, not one: the product, the glass seal and the installation. ENERGY STAR notes installation warranties are often shorter than five years, so ask whether the installers are employees or subcontractors.
5. Check on install day that the windows delivered match the order, photograph the labels, and test every window before the crew leaves.
6. Plan for lead time. High-performance windows often take six to eight weeks, sometimes up to 12.

The tax credit is gone for 2026

ENERGY STAR’s pages still mention a federal credit of up to $600 for qualifying windows. The IRS says that credit applies to items placed in service by December 31, 2025. Windows installed in 2026 don’t qualify. Ask installers about state or utility rebates instead.

If you’re replacing a whole house of windows, our guide to paying for a big home repair compares the financing options.

Your next step

Pick the coldest room in the house and do the smoke test this weekend. Caulk and weatherstrip what’s leaking, then live with it for a few cold weeks. If the room is still uncomfortable, or the windows are failing, start getting quotes. For the rest of the season’s checklist, see the fall-to-winter list, and for how long new windows typically last, see how long things last.

Questions readers ask

Do new windows save enough energy to pay for themselves?

Usually not quickly. The Department of Energy says ENERGY STAR windows can cut annual energy bills by about 7% to 15% or more, depending on where you live and what you're replacing. At around $500 a window, the payback is long. Replace for rot, broken windows, comfort, noise or resale, and count the energy savings as a bonus.

Are storm windows worth it?

For single-pane windows in good repair, often yes. ENERGY STAR estimates low-e storm windows save about $350 a year on average over single-pane glass, and that the extra cost of the low-e version pays back in about three years.

How much does window replacement cost in 2026?

This Old House's 2026 survey puts the average at about $517 per window installed, from about $453 for aluminum to $564 for fiberglass, with a typical project of seven windows around $7,200.

Is there a tax credit for new windows in 2026?

The federal Energy Efficient Home Improvement Credit, which covered up to $600 for qualifying windows, applies to items placed in service by December 31, 2025, according to the IRS. Check for state or utility rebates instead.