🌡️ Free Tool
IECC Climate Zone Lookup
Find your climate zone and the U-factor and SHGC requirements that apply to your window replacement project. Select your state below.
Find Your Climate Zone
Select your state to see climate zone and current energy code requirements. For multi-zone states, county breakdowns are shown.
All States — Climate Zone & Code Reference
Primary zone shown. Multi-zone states vary by county. Requirements shown are for the current adopted state energy code.
| State | Primary Zone(s) | State Energy Code | Max U-Factor | Max SHGC |
|---|---|---|---|---|
| Alabama | 3 | 2015 IECC | 0.32 | 0.25 |
| Alaska | 7–8 | 2018 IECC | 0.22 | NR |
| Arizona | 2–5 | 2018 IECC | 0.32–0.40 | 0.25 (Zones 2–3) |
| Arkansas | 3–4 | 2018 IECC | 0.32 | 0.25 (Zone 3) |
| California | 2–6 | Title 24 (2022) | See Title 24 | See Title 24 |
| Colorado | 5–6 | 2021 IECC | 0.27 | NR |
| Connecticut | 5 | 2021 IECC | 0.27 | NR |
| Delaware | 4 | 2021 IECC | 0.27 | NR |
| Florida | 1–3 | FL Energy Code (2018 basis) | 0.50 (Z1), 0.40 (Z2), 0.32 (Z3) | 0.25 |
| Georgia | 3–4 | 2015 IECC | 0.32 | 0.25 (Zone 3) |
| Hawaii | 1 | 2006 IECC (local varies) | 0.50 | 0.25 |
| Idaho | 5–6 | 2018 IECC | 0.30 | NR |
| Illinois | 4–5 | 2021 IECC | 0.27 | NR |
| Indiana | 4–5 | 2021 IECC | 0.27 | NR |
| Iowa | 5–6 | 2021 IECC | 0.27 | NR |
| Kansas | 4–5 | 2018 IECC | 0.30–0.32 | NR (Z4), 0.25 (Z3) |
| Kentucky | 4 | 2018 IECC | 0.32 | NR |
| Louisiana | 2–3 | 2015 IECC | 0.32–0.40 | 0.25 |
| Maine | 6–7 | 2021 IECC | 0.27 | NR |
| Maryland | 4–5 | 2021 IECC | 0.27 | NR |
| Massachusetts | 5–6 | 2021 IECC | 0.27 | NR |
| Michigan | 5–6 | 2015 IECC | 0.30 | NR |
| Minnesota | 6–7 | 2020 MN Energy Code | 0.27–0.22 | NR |
| Mississippi | 3 | 2015 IECC | 0.32 | 0.25 |
| Missouri | 4–5 | 2018 IECC | 0.30–0.32 | NR |
| Montana | 6 | 2018 IECC | 0.30 | NR |
| Nebraska | 5–6 | 2018 IECC | 0.30 | NR |
| Nevada | 3–5 | 2018 IECC | 0.30–0.32 | 0.25 (Z3) |
| New Hampshire | 6 | 2018 IECC | 0.30 | NR |
| New Jersey | 4–5 | 2021 IECC | 0.27 | NR |
| New Mexico | 3–5 | 2018 IECC | 0.30–0.32 | 0.25 (Z3) |
| New York | 4–6 | 2020 ECCCNYS | 0.30–0.32 | NR |
| North Carolina | 3–5 | 2021 NC Energy Code | 0.27–0.30 | 0.25 (Z3) |
| North Dakota | 6–7 | 2018 IECC | 0.27–0.30 | NR |
| Ohio | 4–5 | 2017 OBC (IECC 2015) | 0.30–0.32 | NR |
| Oklahoma | 3–4 | 2016 IECC | 0.32 | 0.25 (Z3) |
| Oregon | 4–6 | 2021 OEESC | 0.27–0.30 | NR |
| Pennsylvania | 4–6 | 2018 IECC | 0.30–0.32 | NR |
| Rhode Island | 5 | 2021 IECC | 0.27 | NR |
| South Carolina | 3 | 2021 SCEC | 0.30 | 0.25 |
| South Dakota | 6 | 2018 IECC | 0.30 | NR |
| Tennessee | 3–4 | 2018 IECC | 0.30–0.32 | 0.25 (Z3) |
| Texas | 2–5 | 2015 IECC (state) | 0.30–0.40 | 0.25 (Z2–3) |
| Utah | 5–6 | 2018 IECC | 0.30 | NR |
| Vermont | 6 | 2020 RBES | 0.27 | NR |
| Virginia | 4–5 | 2021 USBC | 0.27 | NR |
| Washington | 4–6 | 2021 WSEC | 0.27–0.30 | NR |
| West Virginia | 4–5 | 2018 IECC | 0.30–0.32 | NR |
| Wisconsin | 6 | Comm 20/21 (IECC basis) | 0.30 | NR |
| Wyoming | 6–7 | 2018 IECC | 0.27–0.30 | NR |
NR = No Requirement. Always verify with your local building department — cities may enforce newer editions than the state minimum.
U-Factor Requirements Guide
Full explanation of what U-factor means, IECC 2018 vs 2021 differences, and what to look for on the NFRC label.
→SHGC Requirements Explained
When SHGC matters, when it doesn't, and how climate zone affects the solar heat gain rules.
→Reading the NFRC Label
How to read the label on your window box and confirm it meets your permit requirements before installation.
→Egress Calculator
Check if your basement window meets IRC R310 egress requirements — instant results.
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