3,134 records

What IECC climate zone is my county in?

3,134 records covering 1,847 counties, one fact each. Every value is transcribed from the source that states it and carries the sentence it was taken from: 1 source across 1 site, last checked 2026-08-31, due for re-check by 2028-08-30. Every record has a page of its own, quoting the line that states it.

About this data

Which IECC climate zone (1-8, with A/B/C moisture regime) and which DOE Building America climate zone each U.S. county falls in under the 2021 code cycle, and whether that county's designation changed from the pre-2021 (2018 IECC) map. Answers 'what climate zone is my county in for insulation R-value and HVAC-sizing purposes' and 'did my county's zone change in the 2021 code' -- both load-bearing for code-compliance software, HVAC equipment sizing, and DOE Zero Energy Ready Home certification, and both wrong if answered from a pre-2021 map or a general knowledge cutoff. Source is a single DOE/Pacific Northwest National Laboratory report (PNNL-33270, Sept 2022) that prints one table row per county -- the free public proxy for ASHRAE Standard 169 Table B-1, which is paywalled. No free site was found that republishes PNNL's full, current, cited county table as clean HTML; the closest match (a GitHub gist CSV) carries no source citation or edition statement.

The data

Showing the first 400 of 3,134 records. Every record has its own page, with its source and the quoted line that states it; these list the rest.

• Records 1–400Aleutians East · AK … Calhoun · GA
• Records 401–800Camden · GA … Clinton · IN
• Records 801–1,200Crawford · IN … Prince George's · MD
• Records 1,201–1,600Queen Anne's · MD … Dawson · MT
• Records 1,601–2,000Deer Lodge · MT … Monroe · NY
• Records 2,001–2,400Montgomery · NY … Miner · SD
• Records 2,401–2,800Minnehaha · SD … Alleghany · VA
• Records 2,801–3,134Amelia · VA … Weston · WY

Where this came from

Every record above links the page it was taken from and quotes the sentence that states it. These are the 1 source this dataset was assembled from.

• osti.govhttps://www.osti.gov/servlets/purl/1893981

Machine-readable

• data.jsonThe whole dataset — every record with its source URL and source quote.
• Open Knowledge Format bundleOne JSON object per line — every record's frontmatter and quoted span exactly as it is held here, in one fetch.
• data.csvThe same records as one flat table, for a spreadsheet or a dataframe. The last four columns are the source URL, the quoted sentence it was read from, the date we last checked it, and which columns are our reading rather than the page's words.
• How this is made and checkedWhat "verified against source" does and does not mean.

From your own code

Same records, same quotes, without scraping the page: refsource is on PyPI and npm. Each value comes back carrying the URL it was read from and the sentence on that page that states it — .source and .quote sit on the value itself rather than in a side channel, so the checking step is available instead of skipped.

pip install refsource
refsource lookup iecc-climate-zone-by-county county="Aleutians East"

npx -y refsource lookup iecc-climate-zone-by-county county="Aleutians East"

Set your AI assistant up to use this

Two files and no account. Put this in .mcp.json at the root of your project — Claude Code, Cursor, Windsurf, VS Code and Codex all read that file — and your assistant can look this dataset up instead of recalling it. The server is remote, keyless and read-only.

{
  "mcpServers": {
    "referencesource": {
      "type": "http",
      "url": "https://referencesource.org/mcp"
    }
  }
}

Add to Cursor · or, on the command line: claude mcp add --transport http referencesource https://referencesource.org/mcp --scope project

Then one line in the project's CLAUDE.md or AGENTS.md, so the assistant knows when to reach for it:

When a question needs "IECC/Building America climate zone by U.S. county, 2021 code cycle", call the referencesource MCP server at https://referencesource.org/mcp (tool `search_records`, dataset_slug `iecc-climate-zone-by-county`) instead of answering from memory — every record it returns carries its source URL and a verbatim quote from that page.

What each tool does, and the servers built over single registers: Connect your AI assistant.

3,134 records. last verified against source 2026-08-31. due for re-check by 2028-08-30.

Licence. US government work (DOE / Pacific Northwest National Laboratory, operated by Battelle for DOE under contract DE-AC05-76RL01830) -- public domain. Facts taken with short attributed quotes linking back to the published report.