By Ruth MacEachern
Product Manager
As any architect, planner or developer knows, the process of building and maintaining any property is hedged around at every corner with various regulations to ensure the safety of occupants. Ventilation is no exception to this rule. As with most of these regulations, compliance with ventilation regulations is required by law, and for peace of mind, it’s worth keeping up to date with developments in the sector. Failures of compliance can incur substantial costs, as well as causing harm to occupants and communities.
Approved Document F: Means of Ventilation of the Building Regulations sets out the legal ventilation requirements for dwellings in England and Wales. Wales and England do have separate versions of the document, though both titled Approved Document F. The Department for Levelling Up, Housing and Communities also published the Domestic Ventilation Compliance guide, which assits architects and developers in meeting the requirements set out in Document F. This covers the installation and commissioning of the most commonly occurring situations, and although it is not exhaustive, it provides clear guidelines for most situations.
Up until recently, this was always a separate document but following the 2021 amendments to Approved Document F this has now been amalgamated into the document itself.
Below is an overview of this document and some consideration of approaches to compliance. It’s essential that the contents are considered early in the planning stage of any new-build project, and for a project which involves mechanical ventilation, it’s strongly advised that planners and developers seek expert guidance on achieving compliance.
Approved Document F provides an overview of those sections of the Building Regulations which apply specifically to ventilation and ventilation-related issues. Architects and developers are likely to be familiar with Approved Documents covering areas such as insulation, and will know that the details of these documents tend to be open to interpretation, at least to some degree. That said, the baseline set out in Approved Document F is fairly clear cut: ventilation must be sufficient to prevent any build-up of condensation liable to threaten the long-term structural integrity of the property. In practice, this means that some form of ventilation system must be in place.
Approved Document F goes on to set out regulations covering the planning, installation and testing of whatever system is implemented. Since a wide range of ventilation options are available, the Document sets out slightly different requirements for the main categories of ventilation system. In essence, these requirements establish minimum standards of air quality, and how they are to be achieved through each method of ventilation.
Approved Document F addresses four main approaches to ventilation. The first of these, passive or background ventilation and intermittent fans, natural ventilation with intermittent extract fans and background ventilators, has historically been the most commonly implemented. Background ventilation typically takes the form of trickle vents in windows, with intermittent extractor fans in areas vulnerable to the accumulation of moisture, such as bathrooms, kitchens and laundry rooms. Document F sets out minimum intermittent extract rates for systems of this kind. The principal challenge for architects and developers wanting to implement a background ventilation system is likely to be achieving these rates. As requirements for energy efficiency and moisture-removal become more stringent, background ventilation has become increasingly less viable as a go-to ventilation solution.
Mechanical Ventilation with Heat Recovery (MVHR) is also considered under Document F. MVHR is a much more technical ventilation system, involving a heat exchanger and two sets of ducting. The ducts draw in external air and expel internal air in a continuous cycle, but the air is directed through the heat exchange unit so that the building’s internal heat is not lost along with the expelled air. This system has the advantage of enormous savings in energy costs, due to the retention of heat. This helps architects and developers to meet regulations concerning energy efficiency.
Other ventilation options are available, but must also comply with specific requirements set out in the Document - including Requirement F1(1) which states the need for adequate means of ventilation which is to be provided for people within the building.
Positive Input Ventilation, or PIV is one such system PIV is more cost-effective to install and provides highly efficient ventilation, although naturally, it does not provide the long-term energy savings of MVHR. In properties designed to achieve high airtightness, MVHR and PIV are likely to be the systems which can most easily meet the minimum airflow standards set out in Document F. To be able to demonstrate compliance with F1(1), the BBA Certificate could be used for the PIV.
The 2021 amendment to Approved Document F itself now included the amalgamated Domestic Ventilation Compliance Guide. This provides information which is spread throughout the document to assist architects, planners, developers and installers to achieve compliance with the regulations set out in Document F. It offers guidance on the types of ventilation system discussed above, with a special focus on installing, testing and commissioning of each system, as well as a discussion of how to achieve an effective handover to end-users. A key change to the updated regulations is that Approved Document F now includes guidance relating to existing dwellings as opposed to just new builds.
The non-domestic compliance guide as a standalone document also sets out recommended minimum energy efficiency standards for components of building services systems, including controls. For systems installed in new buildings, the standards are design limits. For new or replacement systems and components installed in existing buildings, the standards represent reasonable provision for complying with the building regulations.
It is important to note that both the information contained within Approved Document F as well as the non-domestic compliance guide covers a range of frequently occurring situations but is not exhaustive and alternative means of achieving compliance with the ventilation requirements in the Building Regulations may be possible.
Approved Document F sets out how ventilation systems should be tested once installed. A three-part testing procedure is recommended. These include initial visual checks to give the ability to detect hazards but also any factors which might cause the system to function less than optimally.
The second stage of the testing procedure comprises functional checks. The system’s components should be prepared for use, for instance, by removing packaging or temporary protection. Each component should be tested separately, again to ascertain whether optimal functionality has been achieved.
The final stage of testing is the most technical, and the only stage specific to ventilation systems. This is the airflow testing. This test is carried out using a properly calibrated airflow device to establish the rate of airflow in litres per second. Specific conditions for this testing are set out in the document, and it is test data obtained under these conditions which should be used to ascertain whether a ventilation system meets the airflow requirements as seen in the Tables in Approved Document F.
Ultimately, building owners and/or occupants will have responsibility for the maintenance and effective use of whatever ventilation system is installed. However, developers have a responsibility to make sure that incoming occupants are properly informed about how to use their ventilation system and prevent its breakdown. For this reason, the Approved Document sets out guidelines for an effective handover.
Any manufacturer’s documentation, such as a user manual, must be handed over, along with information about the manufacturer and contact details where relevant. In addition, information specific to the installation must also be provided. This might include the location of units, ducts, terminals, control panels, filters and/or thermostatsInstructions on cleaning and maintenance should be provided, including instructions on the whereabouts of filters. In a system which incorporates sensors, end users should be advised as to how these can be recalibrated.
At the back of Approved Document F, there is a checklist to help responsible parties ensure that compliance has been achieved. This includes detailed guidance on how to checkdesigned airflow rates against actually achieved and measured airflow rates. The finished checklist must be signed off by the person responsible for installation.
Although Approved Document F provides as much information as possible relating to the compliance of ventilation in existing and new build dwellings in practice its recommendations can be hard to achieve without expert input. In the case of simpler ventilation systems, such as natural ventilation, background ventilators and intermittent fans many builders may be able to achieve compliance. However, where the ventilation situation is complicated, or where a mechanical ventilation solution has been implemented, it’s recommended that planners and developers seek the advice of a ventilation specialist at the earliest possible stage. Compliance is most easily achieved when it is prioritised in planning, and overseen by someone with ventilation experience.
EnviroVent provides a comprehensive service to architects, planners and developers, ensuring compliance with ventilation regulations from the beginning of a project to handover. Our expertise ensures that the long-term costs of failing to comply can be avoided, and we can also recommend the best ventilation solutions for your project. Contact us to request a quote today!
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