Part O assessment that fits your assessor workflow.
Sit Part O cleanly between your SAP, BREL and as-built deliverables. Per-window Appendix D Equivalent Area calculations, branded reports and the audit-quality workings Building Control expects from an assessor.
- Per-window Appendix D Equivalent Area engine
- Part Q restrictor and security adjustment built in
- Branded report with assessor name, qualification & registration number
- Save unlimited assessments to your account dashboard
Why other Part O tools frustrate assessors
You are signing your name to the report. You need the underlying workings to be defensible - not a black box.
Hidden Equivalent Area maths
Most tools quote a free area number without showing the Appendix D opening-angle factor. Ours shows the full per-window workings, every time.
No assessor signature block
Building Control wants your name, qualification and registration number on the report. We have a dedicated assessor profile section.
Re-keying data from SAP
You have already entered floor area, glazing and ventilation strategy for SAP. We let you reuse a saved project as a template for the Part O run.
Built for the assessor in mind
Designed by reviewing the exact workings Building Control queries, not by guessing what a calculator should output.
Appendix D Equivalent Area engine
Window-by-window calculation with opening type, opening angle, restrictor settings and ground-floor Part Q adjustment fully exposed.
Risk-zone classification (AD-O App. C)
London and central Manchester postcodes classified per AD-O Appendix C Tables - no manual lookup.
Free area / purge ventilation logic
AD-O Tables 1.3/1.4 free area requirements plus the 4% bedroom check and 55%-of-glazing rule, applied automatically.
Account dashboard with templates
Save common dwelling types as templates and apply them across multiple jobs from one assessor account.
Part O postcode risk checker
Find out instantly whether your site falls in a Part O High-risk overheating area. Based on Approved Document O, Appendix C (London Table C1 and Manchester Note C3). No sign-up required.
Risk zones are defined in Approved Document O, Appendix C (2021 edition).
Assessor FAQs
Add Part O to your service line in 10 minutes
Set up your assessor profile, run the first job, ship a branded report. No subscription - pay per assessment.