Windows & Doors

Windows and doors, in plain terms

A modern replacement window is two or three panes of glass sealed into an insulated unit, set in a frame of vinyl, wood or fiberglass. The gap between panes is usually filled with argon, and the glass carries a low-E coating — a microscopically thin layer that reflects heat back where it came from. Together those are what make a new window feel different to stand beside in January.

Two numbers appear on the sticker. U-factor is how readily heat passes through the whole unit, and lower is better. SHGC is how much of the sun's heat the glass lets in, where a lower number keeps more summer heat out and a higher one lets more winter sun through. For our climate the sensible answer usually balances the two rather than chasing either to an extreme.

What new windows do well

They stop the draught you can feel

Most of the discomfort near an old window is air leaking around a failed sash and frame, not heat passing through glass. That is the part a proper replacement fixes immediately and noticeably.

They are quieter

Sealed insulated units cut road and wind noise. It is rarely the reason people replace windows and frequently the thing they mention afterwards.

They stop being a maintenance job

No more painting, reglazing, or fighting a sash that has not opened since the Clinton administration. Modern units tilt in to clean from inside.

Where to be realistic

Energy savings are real but slow

Windows are among the more expensive efficiency upgrades per unit of heat saved — attic insulation and air sealing generally do more per pound. Comfort, quiet and appearance are the honest reasons to replace windows; the bill helps rather than pays for it.

The installation matters as much as the window

A well-specified unit fitted without proper flashing, insulation and air sealing around the frame will underperform a modest window installed correctly. This is not an area where the sticker tells you what you are getting.

Condensation is usually your house, not the window

Moisture on the inside surface of new glass generally means indoor humidity is high — sometimes because the house is now sealed better than it was. Moisture between the panes is different: that is a failed seal, and it is a warranty matter.