Ventilation testing and commissioning for Part F
Air flow rates for mechanical ventilation in new homes must be measured and reported to building control. TestConnect books competent ventilation testers, batches plots into one visit, and records each terminal's measured flow against the plot.
What is tested
Approved Document F, Volume 1: Dwellings (2021 edition, in effect since 15 June 2022) says the air flow rate of all mechanical ventilation fans should be tested: intermittent extract fans, cooker hoods, continuous extract fans or terminals, and continuous supply fans or terminals (paragraph 4.9). The measured flow at each terminal, in litres per second, is recorded on the commissioning sheet in Appendix C.
What the regulations say (England)
| Topic | What it says |
|---|---|
| Testing | For a new dwelling, the person carrying out the work must make sure the mechanical ventilation air flow rate is tested by an approved procedure, and give notice of the results to building control (Regulation 42). |
| Notice | No later than five days after the final test is carried out (Regulation 42(3)). |
| Equipment (2021 edition) | A calibrated air flow device with a proprietary hood, accurate to ±5%, calibrated within the last 12 months at a UKAS-accredited calibration centre (paragraph 4.10). |
| Commissioning | A commissioning notice is given to building control (Regulation 44), and a copy of the completed commissioning sheet goes to the owner of the home (paragraph 4.14). |
What changes in 2027
The 2026 edition of Approved Document F, Volume 1 takes effect on 24 March 2027 (24 September 2027 for higher-risk building work). It keeps the rule that air flow rates in new dwellings must be measured and the results given to building control (paragraph 4.11), and adds more detail on who measures and with what:
- apart from a single intermittent extract fan in an existing home, the person commissioning and testing should be a member of an organisation that regularly and independently checks their competence, for example a relevant competent person scheme (paragraph 4.10);
- continuous extract and supply fans should be measured with a powered flow hood. A vane anemometer may still be used for intermittent extract fans;
- the device and its hood should have been calibrated together within the last 12 months at a UKAS-accredited centre, across a range from at least 4 l/s up to the system's maximum design flow.
See also Part L 2026: what changes for air testing, which covers the wider Future Homes Standard changes.
This is a summary of published guidance, not compliance advice. Check what applies to your site with your building control body, and check the transitional arrangements for work already under way. This page covers England.
How TestConnect helps
- Testers can keep their scheme membership and the calibration dates of their flow hoods and other equipment on their profile, with reminders before anything expires.
- Ventilation visits batch several plots on one site into one trip.
- Readiness checks confirm the system is installed and powered before the visit.
- Measured flows per terminal, fails and re-commissioning are kept against each plot.
Sources
- Approved Document F, Volume 1: Dwellings, 2021 edition and 2026 edition (GOV.UK)
- The Building Regulations 2010, Regulation 42: mechanical ventilation air flow rate testing (legislation.gov.uk)
- Elmhurst Energy: the Future Homes Standard
Last checked: October 2026.