Wisconsin is in the ENERGY STAR Northern climate zone, which requires a U-factor of 0.22 or lower with no SHGC requirement, or 0.23 to 0.28 paired with an SHGC of 0.32 or higher. Lower U-factor means better insulation. In this climate U-factor matters far more than SHGC — plenty of windows marketed as energy efficient meet the national standard and miss the Northern one, so check the NFRC label rather than the brochure.

Insert replacement keeps the existing frame and is faster and cheaper, but it only works if that frame and sill are genuinely sound, and you lose an inch or two of glass area. Full-frame takes the opening back to rough framing, which is necessary when there’s rot, when the originals are failing at the sill, or when the flashing needs correcting. On pre-1970 Madison housing stock we recommend full-frame more often than not, and we check every sill before advising either way.

Spring through fall is easiest, but window replacement runs year-round here. Crews work one opening at a time so the house is never open to the weather, and winter installs are routine. Manufacturer lead times are typically shortest in late winter, which often means a faster start date than a summer order.

It depends where the moisture is. Condensation on the room-side surface usually means indoor humidity is too high for the glass temperature — common in winter, and often fixed with better ventilation rather than different windows. Fog between the panes means the insulated glass seal has failed and the unit needs replacing, which is a manufacturer warranty claim. Frost on the frame in one corner points at an air leak at the rough opening, which is an installation issue and covered under our warranty.