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By Ruth MacEachern
Product Manager
The Approved Documents are produced by the Government under the Building Act 1984 to ensure the correct and safe practices in the construction industry. The collective documents, of which there are currently 18, provide secondary guidance in terms of meeting the requirements of Building Regulations.
Approved Document F: Means of Ventilation was previously updated in 2010, but in December 2021 following lengthy consultations and the beginning of the movement to the Future Homes Standard in 2025, a revised edition was released. This comes into effect in England on 15th June 2022.
Wales, Scotland and Northern Ireland have their own variant of these regulations which are gradually being released as 2022 progresses, with Wales and Scotland having released theirs in May and June of this year. Northern Ireland has not currently announced any consultation or change. Would you like to know all about the new Approved Document F? Here you can watch our full webinar where we will explain the new changes, technical requirements and the new terminology introduced.
Approved Document F, was previously a single document that focused upon ventilation within new dwellings, as well as practice for basements, conservatories and more specific methods of ventilating properties. Non-residential buildings were briefly referred to, but were linked to other commercial documentation such as the CIBSE guide. However, in the 2021 edition, there are sections directly aimed at the ventilation of existing dwellings.
The Domestic Ventilation Compliance Guide was then coupled alongside Approved Document F, providing the ‘how to’ in terms of meeting compliance and included commissioning tables and instructions, system-specific diagrams and further details in relation to documentation to be provided to the occupant on completion.
In the 2021 revision, Approved Document F has been split into two volumes, with Volume 1 relating to dwellings, and Volume 2 for non-dwellings. The Domestic Ventilation Compliance Guide has then been amalgamated into the document for ease of understanding and use. As well as this, there are two sections that specifically provide guidance for existing dwellings and the commissioning detail which was scarcely mentioned in the 2010 version.
A key change found within the revised Approved Document F is the re-naming of the ventilation methods. These were previously referred to as Systems and then alternative means if required.
In terms of alternative ventilation systems such as PIV or Positive Input Ventilation, when the 2021 proposals were announced the Government issued a response due to the lack of reference to alternative ventilation systems which was queried. This states that providing that the requirements of Regulation F1(1) ‘There shall be adequate means of ventilation provided for people in the building’ are met, and that compliance can be proven such as with a BBA Certificate then this will suffice. The response went on to advise that the Approved Document refers to common ventilation situations and should alternative methods of ventilation be required, then providing that the F1(1) requirement is met then this will be acceptable.
Another key change is the increase in the whole dwelling ventilation rates in a property. When specifying ventilation for a property, mainly for systems or for the ventilation of a whole property, the floor area is to be taken which is then multiplied by 0.3 per m². This figure is then put against the corresponding figure from Table 1.3 (2021 version) based upon the number of bedrooms as a minimum ventilation rate for the whole dwelling.
Between the 2010 and 2021 versions there has been an increase of 6l/s per person with a one bedroom property which was previously at 13l/s, now 19l/s. This is a significant uplift and will affect decisions in terms of choosing a suitable product to be able to comply with the regulations.
The requirements for background ventilation in relation to Continuous Mechanical Extract Ventilation (MEV and d-MEV) in England have also changed in the 2021 version of Approved Document F. These usually take the form of trickle vents in windows, but through-wall ventilators can potentially be utilised however both options usually require factoring in during the design phase as retrofitting can be costly and time consuming.
In the 2010 regulations, if a property had an air permeability of 5 or greater this was considered to be fairly leaky and therefore no background ventilation was required. In properties with an air permeability of less than 5 and therefore more airtight, there was a requirement of 2,500mm² of background ventilators in each habitable room.
This has now changed and in the 2021 version of the regulations, properties of all air permeabilities to utilise trickle ventilation in habitable rooms. The amount has increased to 4,000mm² per habitable room, and within the accompanying notes it states that the total number of background ventilators must not be fewer than the number of bedrooms in the dwelling plus an additional two ventilators. For those properties using Natural Ventilation, both the rates and methods of calculating the requirement, which are now done per room, are also included in the revised document.
A further change is the additions of Section 2 and Appendix B which relate to IAQ and VOCs. Tables are provided in both areas which show names of harmful contaminants, exposure limits, times and advice on what action to take should the property exceed these levels. The figures within the tables are provided by the Office for Health Improvement and Disparities (formerly Public Health England) and the WHO, and whilst at the minute the data reads as a guide only and advises to seek expert advice if any clarity is needed, the rising importance of both indoor air quality and minimising VOCs, particularly in light of the Covid-19 pandemic is something that will increase as the we edge closer towards Net Zero.
The culmination of the above key changes in the regulations show the progress made towards achieving the primary elements of the Future Homes Standard. Whilst there may be further interim documents between now and 2025, these amendments provide a stable initial framework to effectively enable sufficient ventilation of both dwellings and non-dwellings in line with increasing levels of air tightness and changing practices within the ventilation sector.
Do you have any questions about how this new law affects your project? Our team of experts will study it and give you professional advice by clicking here.
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