Local research · updated July 2026
Replacement Windows in Janesville, Wisconsin
Janesville sits on the Rock River in southern Wisconsin near the Illinois line — GM plant-closure legacy, freeze-thaw winters, and older industrial stock. Of the city's housing units, 63.2% predate 1980 and the median year built is 1972. Rock County is ENERGY STAR Northern / IECC 5A (southern Wisconsin tip milder than Madison/Fox Valley 6A, still cold enough for Northern U-factor): ultra-low U-factor is the heating priority. Replacement here is cold-climate glass on aging manufacturing-city openings.
Short answer
In Janesville, a standard replacement window (double-hung, casement or slider) typically costs $525–$2,985 installed. Bay and bow windows run $2,625–$8,390+, and a sliding patio door $1,575–$5,245. Frame material and the glass package decide where a project lands in that range.
Planning ranges built from NREL and BLS cost data, localized to Janesville with the BEA Regional Price Parity for Janesville-Beloit, WI (2024). How we estimate →
63.2%
of Janesville homes were built before 1980, the era of single-pane and early aluminum windows
Source: U.S. Census Bureau, 2019–2023 ACS 5-Year Estimates
1972
median year built across Janesville's 29,171 housing units
Source: U.S. Census Bureau, 2019–2023 ACS 5-Year Estimates
U ≤ 0.22
the ENERGY STAR v7.0 number that matters most in the Northern zone
Source: EPA ENERGY STAR v7.0
Window installers in Janesville
Compare companies serving Janesville. Request a free, no-obligation quote and we route it to the company or a vetted local installer.
| Company | Location | Request a quote |
|---|---|---|
 4.8 · 200,000+ reviews | Janesville, WI | Get a quote → |
| 1Champion Replacement Windows of MadisonChampion | Madison, WI | Get matched → |
| 2Feldco Windows, Siding, Doors & Roofing of RockfordFeldco | Rockford, IL | Get matched → |
| 3Mad City RemodelingMad City Windows | Madison, WI | Get matched → |
| 4Mad City Windows & Baths of MadisonMad City Windows | Madison, WI | Get matched → |
| 5Pella Windows and Doors Showroom of Madison, WIPella | Madison, WI | Get matched → |
| 6Window World of MadisonWindow World | Madison, WI | Get matched → |
| 7Window World of RockfordWindow World | Loves Park, IL | Get matched → |
Renewal by Andersen of Janesville
4.8 · 200,000+ reviewsShowrooms in Janesville & Madison · serving the Janesville metro
Full-service manufacturer and installer, transferable warranty, local crews. Why it's our Top Pick
Get a quote →Listings compiled from manufacturer dealer locators and public business records. Premier and Sponsored Partners pay for placement and are labeled as such; star ratings shown are reported by the partner, with the source and date beside them. See our advertising disclosure. Contacting a company shares your details with it (or a vetted local installer) so it can reach you about your project.
Are you a window company? Claim your listing to take quote requests from Janesville homeowners directly.
What drives window decisions in Janesville
- Northern / 5A: U-factor ≤ 0.22 under ENERGY STAR v7.0 — not soft North-Central brochure numbers.
- Older industrial stock: lead-safe work and non-standard openings common.
- Freeze-thaw and snow stress putty and sills every winter.
- Wisconsin utility / Focus on Energy pathways; 25C expired.
Replacement windows & doors by type in Janesville
Local cost ranges and Northern-zone efficiency guidance for each window and door style, specific to Janesville homes:
Ranges localized to Janesville's cost level: national planning ranges shifted by the BEA Regional Price Parity for Janesville-Beloit, WI (93.7, U.S. = 100; 2024). How we estimate local costs →
Efficiency requirements for Janesville's climate
Janesville sits in the ENERGY STAR Northern zone (IECC zone 5A (cold, moist), Rock County). Under the v7.0 specification, qualifying windows need a U-factor of 0.22 or lower with a solar heat gain coefficient (SHGC) of at least 0.17. Heating-dominated climate: the window must hold heat in (very low U-factor) while still letting some free solar warmth through in winter (minimum SHGC). Equivalent-performance tradeoffs allow U-factors of 0.23–0.26 when paired with progressively higher solar gain.
Not sure what these numbers mean? Read our plain-English guide to U-factor and SHGC.
What replacement windows cost here
Southern Wisconsin pricing sits between Rockford IL and Madison rates. Old openings erase cheap-window promises. Federal 25C is gone; Focus on Energy is a realistic path.
For a breakdown by frame material and install type, see our full cost guide.
Rebates & incentives in Wisconsin
The federal window tax credit (25C) ended for projects placed in service after December 31, 2025. If your windows were installed in 2025, you can still claim it on your 2025 return — but for new projects there is no federal window credit. State and utility programs are now the main source of window incentives.
Wisconsin has been rolling out IRA Home Energy Rebate programs; whole-home efficiency retrofits can include windows within a modeled-savings project. Confirm current availability before promising rebate dollars.
- Focus on Energy (statewide). Focus on Energy is Wisconsin's statewide utility efficiency program; it incentivizes audits and weatherization, with windows typically part of a broader whole-home efficiency package. (Focus on Energy program pages)
Wisconsin enforces the statewide Uniform Dwelling Code (UDC); Milwaukee permits through the Department of Neighborhood Services. Zone 6 winters make low U-factor windows effectively essential for permitted replacements.
Replacement windows in nearby metros
Not in Janesville proper? These nearby markets carry the same local research: housing-age data, climate-zone specs, and current rebate status for each city:
Janesville window replacement FAQ
›Do I need a permit to replace windows in Janesville?
Usually yes for full replacement. City of Janesville Building Division. Confirm the installer pulls the permit.
›What efficiency numbers should windows hit?
ENERGY STAR Northern and IECC 5A: U-factor 0.22 or lower under v7.0. This is colder than North-Central 4A packages. Read the NFRC label.
›Are there rebates?
Federal 25C expired December 31, 2025. Check Focus on Energy and local utility programs.
›Restore original sash or replace?
Sound wood plus storms can work. Full replacement when sashes are rotted or seals have failed systemically.
Sources
- — U.S. Census Bureau, American Community Survey 5-Year Estimates (B25034, B25035)
- — EPA ENERGY STAR Version 7.0 Residential Windows specification
- — DOE/PNNL IECC climate zone assignments by county
- — NWS Milwaukee / Chicago; NOAA winter climatology
- — IRS, 25C Energy Efficient Home Improvement Credit (P.L. 119-21)