By Paul Williams, Domus Ventilation Product Manager.
Changes to Building Regulations ‘Approved Document F, Volume 1: Dwellings’ (ADF1) came into effect on 15th June 2022. It gives guidance on how to comply with Part F Ventilation of Building Regulations. However, not all new building projects were initially covered under the revised ADF1. Where a building notice, initial notice, or full plans for building work that were submitted to a local authority before 15th June 2022, and where the building work commenced by 15th June 2023, compliance with these revised regulations was not compulsory. However, as of 15th June 2023, the transitional phase is over and now compliance is required by all. Here, we recap the four key changes that you now need to accommodate in your ventilation design.
1. Increased ventilation rates
Across all sizes of properties, minimum ventilation rates, now based on the floor areas and number of bedrooms per property and no longer with predicted occupancy rates, have been increased as follows: To achieve these new ventilation rates, mechanical ventilation systems in the form of Mechanical Extract Ventilation (MEV) and Mechanical Ventilation with Heat Recovery (MVHR) are the most proficient option.
2. Background ventilation sizing
Background ventilation is the passive supply of external air into a room via ‘a small ventilation opening’, such as intermittent extract fans, trickle vents in windows and airbricks in the wall. Previously, the size of the background vent was determined by the size of the property. Now, this is to be calculated on a room-by-room basis to ensure adequate ventilation throughout a property. This is likely to mean an increase in the number and size of background vents. Certainly, it will mean considerably larger grilles are required, which aren’t aesthetically pleasing and can’t be covered up. In the case of extract only systems, such as MEVs, the background vents size has been doubled from 2500mm2 to 5000mm2.
3. Natural ventilation options reduced
Natural ventilation systems, such as the background vents mentioned above, are now only an option for less airtight homes with a design air permeability of ≥5.
4. Compliance: no excuse for failure
Under the revised ADL1, reporting has been tightened up to drive compliance. Now a new style commissioning sheet featuring a compliance report and photographic evidence must be provided to Building Control Bodies and the building owner, along with a Home User Guide specifically for householders. Domus Ventilation is a manufacturer of market-leading ventilation systems that save energy and improve indoor air quality.
vent.info@domusventilation.co.uk
