We are members of the
Installation Assurance Authority.
The Installation Assurance Authority (IAA) is the industry body that provides an assurance framework under a single compliance platform and covers consumer protection, technical guidance, Certification, Competent Persons Scheme (CPS), installer surveillance, monitoring, training and carding.
The IAA framework gives homeowners, key stakeholders, and funders the confidence that insulation work is carried out to the highest standards and subject to rigorous surveillance, which helps ensure it is done ‘right the first time’.
Background Ventilation Assessment of Existing Buildings – PAS 2035
PAS2035 PATHWAYS & PROCESS
Retrofit – PAS2035
PAS2035 provides a specification and best practice guidance for low-energy domestic retrofit and refurbishment projects.
A central objective of PAS2035 has been to encourage due consideration of balancing insulation upgrades with air leakage, infiltration, and ventilation provision as part of the whole house retrofit plan.
As such, it augments the current Building Regulations ‘make no worse’ principle by seeking to ensure that unsatisfactory existing ventilation provisions are upgraded as part of EEM retrofit and providing more prescriptive solutions.
Assessment Pathways
Pathway A – An overview of the building, including the services currently installed – Such as ventilation, heating, hot water, lighting, and any control measures.
Pathway B – Location of the services and where installed, plus identifying if they are working correctly. Use Annex C to determine if the systems installed are adequate and appropriate.
Pathway C – Besides B, an air pressure test is also commissioned.
This pressure test can either use a Blower Door (50pa) or a Pulse (4pa).
If either Pathway ‘B’ or ‘C’ are undertaken, there is a need to verify if the building’s current ventilation strategy is adequate and appropriate.
Airtightness and Ventilation
When the insulation and airtightness of the building fabric are improved, adequate ventilation must be maintained.
Airtightness is not the same as ventilation, which is the controlled airflow in and out of the building.
However, they are closely related, so it’s essential to recognise the ventilation requirements under PAS 2035.
With Pathway A and B projects, there is no explicit requirement for an airtightness test. Still, it is essential for there to be an assessment of the ventilation needs for the building before any works and for the ventilation post works to be confirmed as ‘adequate’.
Airtightness and Ventilation
Pathway C Projects
Where the retrofit design includes any building fabric improvement (e.g., insulation, replacement windows, and a ventilation upgrade), it shall also have an appropriate air-tightness standard for the dwelling.
After the work has been completed, the retrofit installer must demonstrate compliance with the airtightness standards using an approved testing method of air permeability in envelopes of dwellings.
If using the above process within PAS2035, then pressure testing the building may be required.
- This can be done using either the Pulse or Blower door method.
- Pulse operates at low pressure (4.0-10.0pa)
- The Blower Door uses a higher pressure (50.0pa)
- Both methods are acceptable to use with PAS2035