Tyson Anderson, Sales & Marketing Director at Titon, outlines the main revisions to the Building Regulations in England in relation to domestic ventilation requirements.
Revisions to the Building Regulations in England were released in December (the documents for Scotland and Wales are still under review) and there are a number of implications for those providing ventilation in dwellings.
It is the intention that the updates ensure adequate ventilation of all types whilst the energy efficiency of housing is improved at the same time and the ventilation document works in conjunction with documents on Energy Efficiency, and for the first time, Overheating. As the saying goes, ‘Ventilate when you Insulate’.
This is all part of the Government’s proposals for the Future Homes Standard, which provides a pathway for highly efficient buildings that are zero carbon ready, better for the environment and fit for the future. Implementation of a full technical specification is scheduled for 2025.
The Approved Document for Ventilation (‘Part’ F) includes a number of changes from the previous one and becomes effective in June 2022. The move towards more energy efficient buildings means that some ventilation levels have been increased to ensure sufficient air changes in dwellings.
In all instances, the revised document redefines what airtight and less airtight levels are, which has a bearing on the type of ventilation system that should be incorporated.
The ventilation systems that are typically utilised in the UK have been labelled slightly differently (see table 1), and are no longer numbered. Passive Stack Ventilation has been removed.
|2021 (effective from 15 June 2022)
|System 1 – Background ventilators and intermittent extract fans
|Natural ventilation with background ventilators and intermittent extract fans
|System 2 – Passive Stack Ventilation
|System 3 – Continuous mechanical extract (MEV)
|Continuous mechanical extract ventilation
|System 4 – Continuous mechanical supply and extract with heat recovery (MVHR)
|Mechanical ventilation with heat recovery
Table 1 – Changes in ventilation systems
As before, other system designs are allowable but need sign off and proof of compliance that they achieve the ventilation rates set in the document.
Mechanical ventilation has been affected with a large increase in per bedroom rate (see table 2). Buildings that are classed as ‘less air tight’2 will require the natural ventilation and background ventilators and intermittent fans, those buildings that are ‘highly air tight’1 will require either continuous mechanical extract ventilation or mechanical ventilation with heat recovery.
|Number of bedrooms
|2013 – Whole dwelling ventilation rate (a.b.) l/s
|2022 – Minimum ventilation rate criterion 1 – by number of bedrooms
Table 2 – Changes in minimal air flow rates.
For background ventilation, which is the continuous change of air that should be occurring in addition to extract ventilation and rapid (e.g. opening windows) ventilation, the document shows an uplift in the amount of ventilation needing to be provided when windows are being replaced. The contractor should now be fitting background vents, usually trickle vents in the windows, whether the previous windows had them fitted or not.
In new build situations, the amount of background ventilation can now be calculated in an easier way and is based on a certain amount per room, rather than based on a total amount for the whole property, which currently means someone having to add this up and allow for certain additional criteria, such as floor area, number of bedrooms and airtightness level, before calculating whether the overall number of vents comply with the total required.
When whole house ventilation systems are being installed, there is an increase in the amount of background ventilation required when used with continuous mechanical extract system. As before though mechanical ventilation with heat recovery (MVHR) does not need background vents, as it is a balanced, controlled ventilation system.
The current Approved Document F also worked alongside a Domestic Ventilation Compliance Guide (DVCG) document, which was designed to help contractors work to certain guidelines and then sign off their work and hand over a compliance Checklist to the end user. The revised Regulation does away with the DVCG, but instead includes Checklists as Appendices within the document, although these are still expected to be completed and handed over to the dwelling owner for their records.
Even though these changes may seem more involved, Approved Document F is much reduced in page count, particularly if you were to include the DVCG too, as now many of the approaches and explanations have been simplified to make compliance easier.
These revisions are all designed to continue the ongoing improvement of the quality of the UK housing stock. The increased emphasis on ventilation in both new and existing dwellings is essential, especially in the current climate where indoor air quality and the build-up of pollutants and airborne viruses is of concern to everyone more than ever.
Tyson Anderson is the Sales and Marketing Director at Titon Hardware Limited and has over 25 years’ experience within the sector.
1 Highly airtight dwellings:
Dwellings that achieve one of the following.
- A design air permeability lower than 5m3/(h·m2) at 50Pa.
- An as-built air permeability lower than 3m3/(h·m2) at 50Pa.
Where the guidance for highly airtight dwellings is followed, dwellings are assumed to have an infiltration rate of 0 air changes per hour. Airtightness level must be proved if no trickle vents are to be fitted into a ‘Less airtight dwelling’.
2 Those dwellings that are not highly airtight dwellings. Where the guidance for less airtight dwellings is followed, dwellings are assumed to have an infiltration rate of 0.15 air changes per hour.