On 15th December 2021, the government published their updated Building Regulations for England, which included amendments to Approved Document F (Ventilation) and Approved Document L (Conservation of fuel and power), as well as the release of a new approved document for Overheating (Part O).

Here, we’ll take a look at how the changes to Part L, in particular, affect one of our services – Air Tightness Testing.

When will the changes to Approved Document L affect Air Tightness Testing?

The new Approved Document L becomes mandatory from 15 June 2022. A grace period will apply for older, previously agreed planning permissions until 15 June 2023.


How will Air Tightness Testing be affected through Approved Document L?

Approved Document L (Conservation of fuel and power) for England will impact Air Tightness Testing profoundly. The updates signal a move towards greater energy efficiency in new buildings.

Greater mandatory testing

The new Approved Document L has made air tightness testing simpler, to some extent. England has, to the best of our knowledge, become the first country in the world to enforce mandatory air tightness testing for every house and apartment. This removes the tricky and complex rules for sampling. 

Buildings affected

JosTec and other air tightness testers will be busy come June 2022! The newly approved document highlights the requirement for an airtightness test to be undertaken on every single dwelling. Buildings that are not dwellings (including extensions that are being treated as new buildings to comply with Part L) must also be pressure tested – some exemptions will apply here.

Changes to equipment calibration

Originally calibration of testing equipment was required every 12 months, however, Airtightness Testers can now choose to recalibrate according to the manufacturer’s guidance. It is still recommended that recalibration is completed at least every 24 months.


How will the wider changes affect existing homes?

The wider legislation will also impact existing homes. Here are some of the main impacts across documents F, L, and O.

  • There will be an enhancement of fabric standards for new thermal elements for work on an existing home. 
  • Introduction of a primary energy and fabric energy efficiency metric for the whole house calculation method for new extensions. 
  • New or replacement heating systems should be designed to accept low-carbon heating in the future. 
  • Revised guidance on work to ventilation systems in existing homes.


The new Approved Document L marks a huge change in housing energy efficiency. It refocuses and tightens the requirements around Air Tightness Testing – which of course we offer at JosTec – alongside greater fabric efficiency and wider carbon emissions reductions.

 The UK will proudly produce some of the most efficient housing stock in years to come, and we’re looking forward to monitoring further progress and serving the population along the way.

Looking for support with Air Tightness Testing? Get in touch here.