This guide is intended for CPHCs and other professionals involved in Phius certification projects. This guide and all associated tools are in no way associated-with, produced-by, reviewed-by, or approved-by Phius or its personnel in any way. All code is provided as-is and without any warranty.
What is Phius Certification?
Phius (Passive House Institute US) certifies buildings that meet strict energy performance standards. A CPHC (Certified Passive House Consultant) submits a WUFI-Passive energy model along with supporting documentation — drawings, product datasheets, thermal bridge calculations, and engineering specs — and a Phius reviewer checks every input against that documentation.
The review happens in rounds (R1, R2, R3…). Each round, the reviewer writes comments in a shared Excel workbook called the Feedback Form. The CPHC responds to each comment, referencing specific files and values. This back-and-forth repeats — typically 4–6 rounds — until every item is resolved and the project achieves certification.
Why Use AI Tools for This?
A typical certification project has hundreds of files across a deeply nested folder structure, and the Feedback Form itself can have 500+ rows of review items spanning multiple Excel worksheets. Common tasks that AI tools handle well:
- Parsing the Feedback Form to summarize what's resolved, pending, or needs a response
- Locating specific files — "find the ERV datasheet for unit 1-3"
- Cross-referencing file paths cited in feedback against actual files in the project folder
- Reading PDFs (datasheets, thermal calculations) to extract specific values
- Drafting CPHC responses that cite the correct documents and file paths
The reference documents below give an AI tool the structural knowledge it needs to do these tasks: where files live, how the Feedback Form is laid out, what status codes mean, and how to parse each sheet.
Key Concept: The Feedback Form
The Feedback Form is a large .xlsx workbook in the
- Feedback Forms/ folder (the leading dash sorts it to the top of the directory).
It is the single source of truth for the entire review — if something
isn't in the Feedback Form, it doesn't exist for certification purposes.
The main sheet has a consistent column layout:
| Column | Contains |
|---|---|
| B | Major section (e.g., "Wall Components", "Systems", "Ventilation / Rooms") |
| C | Sub-section (e.g., "Assembly", "Parameters") |
| D | Item identifier (assembly type like RT-01, WT-04.E, or a device name) |
| E | Parameter category (e.g., "Geometry", "Basic Parameters") |
| F | Specific field being reviewed (e.g., "U-glass:", "Framing:") |
| G onward | Alternating Certifier Comments / CPHC Response columns — one pair per review round |
The workbook also contains supporting worksheets (Thermal Bridges, Win Rev, ERVs, DHW Pipe Lengths, and others) that vary by form version. The reference doc below covers both older (V4.8) and current (V5.6+) layouts.
Reference Documents
We maintain two reference documents formatted specifically for AI tools. These are plain markdown files — no HTML, no front-matter — containing the complete folder hierarchy and Feedback Form parsing rules. They are hosted at stable URLs, so when we update the guidance (new form versions, folder changes), anyone using these URLs gets the current version automatically.
Phius project folder structure — the full directory tree, file naming conventions (YYMMDD dates, _Archive folders), and what each folder contains (WUFI model, drawings, datasheets, calculations, on-site verification).
Feedback Form parsing guide — how to detect the form version, identify the active sheet, locate review round columns, interpret status codes (Ok, Pending, dashes, ditto marks), parse row-by-row with Python/openpyxl, and resolve Dropbox file path cross-references.
Using These Docs with Any AI Tool
The reference docs work with any AI tool that can read a URL or accept pasted text. The key idea: give the AI the reference material before asking it to work with your Phius project. Think of it like handing someone the project template and the current feedback sheet before asking them to work on a certification round.
| Tool | How to use |
|---|---|
| ChatGPT | Paste the reference doc URL into your prompt — ChatGPT will fetch and read it. Or copy the markdown content directly into your message. |
| Cursor / Windsurf | Add the reference doc URL as context using @URL, or save the markdown file locally and add it with @file. |
| GitHub Copilot Chat | Paste the reference doc content into the chat, or save it locally in your project and reference it. |
| Claude Code | Use WebFetch to pull the doc into context, or install a pre-built skill (see below) that does this automatically. |
| Any other tool | Copy the markdown content from the URL and paste it into your AI conversation as context. |
Example Workflows
Once your AI tool has the reference docs loaded, here are typical tasks you might ask for help with:
Summarize review status
"Parse the Feedback Form and tell me which sections have open items."
The AI reads the Excel file with openpyxl, finds the latest review round columns,
and classifies each row as resolved (starts with "Ok"), pending, or action-needed.
Locate a specific file
"Where's the ERV datasheet for unit 1-1?"
Using the folder map, the AI knows to look in
2. Datasheets & Specs/1. HVAC/2. Ventilation/ and can search for matching filenames.
Cross-reference a feedback item
"The reviewer cited '.../2. Datasheets & Specs/4. Insulation/1. Rigid/...' —
verify the file exists and extract the R-value."
The AI strips the Dropbox prefix, resolves the path relative to the certification folder,
confirms the file exists, and reads the PDF to extract the value.
Draft a response
"For assembly type RT-01, the reviewer asked about the U-value. Read the thermal
calculation PDF and draft a response citing the correct file path."
The AI finds the Flixo result PDF in 3. Calculations/2b. Flixo [2D]/,
reads it, extracts the U-value, and drafts a response in the format the reviewer expects.
Claude Code: Automated Skill
If you use Claude Code, you can install a skill that automatically loads the reference docs whenever a Phius certification task comes up. This section is Claude Code–specific — if you use a different tool, the reference docs and general guidance above are all you need.
How It Works
A skill is a markdown file (SKILL.md) that Claude Code loads when a task matches
its trigger description. The phius-certification skill triggers on keywords like
"feedback form", "certification", "datasheets", assembly type codes (RT-01, WT-04), or when
the workspace looks like a Phius project folder (numbered folders like
0. WUFI-Passive Energy Model/).
When triggered, the flow is:
- Claude loads the skill — a compact instruction set with quick-reference tables
- The skill tells Claude to
WebFetchboth reference docs from this site - Claude now has the complete folder structure and Feedback Form parsing rules in context
- You ask your question and Claude can navigate the project, parse the Excel file, locate files, etc.
Because the reference docs are hosted here, they stay current — when we update folder guidance or add support for a new form version, every skill user gets the update automatically on their next task. No reinstall needed.
Available Skill
Navigate Phius certification project folders, parse the Feedback Form, track review status, and cross-reference documentation. Triggers automatically when working in a Phius project folder or when you mention certification, feedback forms, or assembly types.
Installation
Option A: One-liner (recommended)
Run this in your terminal:
mkdir -p ~/.claude/skills/phius-certification && \
curl -sL https://docs.passivehousetools.com/skills/phius-certification.md \
-o ~/.claude/skills/phius-certification/SKILL.mdOption B: Manual download
- Click "Download SKILL.md" above
- Create the skill directory:
mkdir -p ~/.claude/skills/phius-certification - Move the downloaded file into it:
mv phius-certification.md ~/.claude/skills/phius-certification/SKILL.md
Verify installation
Run ls ~/.claude/skills/phius-certification/ — you should see SKILL.md.
Then start a Claude Code session in a Phius certification folder and try:
- "Summarize the open items in the latest Feedback Form"
- "Where's the ventilation datasheet for ERV 1-1?"
Claude should automatically load the skill, fetch the reference docs, and help with the task.
Related Skills
The phius-certification skill works well alongside these other skills
for complete certification workflows:
- wufi-xml —
Verify values in the WUFI-Passive energy model (
.xml) against feedback items. Useful when the reviewer questions a model input and you need to confirm the XML value. - pdf — Extract data from product cut-sheets, datasheets, and drawings referenced in the Feedback Form. Especially useful for reading R-values, U-values, and equipment specs from manufacturer submittals.
- xlsx — Read and write Excel workbooks. Used under the hood when parsing the Feedback Form, Phius calculators, and DHW pipe length takeoffs.