The Chartered Institution of Building Services Engineers (CIBSE) has published the final version of its airtightness testing methodology, TM23 Testing buildings for air leakage (2022) . This new methodology is due to come into force in England from the 15th June 2022, replacing the current ATTMA standards.

iATS members can now access the document for free using code TM23_FREE

The release of this document follows the recent update to Approved Document L in England, which states that airtightness tests should be performed following the guidance in the approved airtightness testing methodology, CIBSE’s TM23. This move is to ensure that the approved methodology for airtightness testing is independent of all organisations with an associated competent person scheme.

Some of the main changes from the current ATTMA standards include:

  • One document covering both Level 1 and Level 2 tests
  • The introduction of Pulse as an alternative airtightness testing method
  • Recommendation to carry out both a pressurisation and depressurisation test, with the final result being an average of the two
  • Changes to sealing requirements for natural ventilation, mechanical ventilation and air conditioning
  • Clarification of the frequency of equipment calibration

Scheme coordinator Jennifer Hartley comments: “The release of an independent airtightness methodology is a positive move in the industry. We are surprised that CIBSE currently is charging non-members for downloading the standard and we are urgently seeking clarification on whether this is likely to change. However, after much discussion with CIBSE we have made sure that iATS members can now access the document for free using a code (Members can get in touch with us should they need this code).

“We were also surprised to read within the document that the calibration frequency for the blower door equipment has remained at 12 months, which contradicts the government’s response to the Future Buildings Standard consultation suggesting calibration was to be required at least every 24 months or in line with manufacturers guidance.

“We welcome an independent body overseeing the standards and look forward to working together with CIBSE and other competent persons schemes to ensure the document sets clear standards for airtightness testers going forwards. This model has worked well in the National Calculation Methodologies of SAP and SBEM and allows schemes to discuss issues affecting their members and improve the industry for all.”

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