Guidance for Passive Vent Use - New Building Regulations 2022

Building Regulations Part F for England 2022 – Guidance for Passive Vents use

On 15^th June 2022 new building regulations come into effect, so there will be new guidance provided. The effect will be to increase the amount of background (trickle) ventilation incorporated into windows for both new builds and when replacing windows. It is important that installations comply with these new standards.

We recommend you read the new building regulation part F . Link here Ventilation: Approved Document F – GOV.UK (www.gov.uk)

This is a summary of the new regulations that apply to dwellings.

Please be aware that the building regulations work using a measure of Equivalent Area (EA) please ensure you understand the difference between EA and Geometric area (GA). A failure here could lead to non-compliance!

Guidance for New Builds

Natural ventilation (Previously system 1 Passive vents and intermittent extract fans).

The minimum number of vents used for a dwelling with one bedroom is 4.
The minimum number of vents used for a dwelling with more than one bedroom is 5.
If a dwelling has Kitchen and living room that are not separate rooms then at least three ventilators the same size as the other habitable area should be provided for the open space.

Where Natural Ventilation is not applicable for new builds:

A dwelling that is Not a less airtight dwelling (a less airtight dwelling has a design air permeability >5m³/Hr@50Pa Or if the as Built air permeability is >3m³/Hr@50Pa).
If a Building only has one façade or 70% of the openings are on one façade.
If there are no windows in the kitchen or external façade where a ventilator can be fitted.

Continuous mechanical extract ventilation (Previously system 3).

The requirement for ventilators in CMEV systems is that a 4000mm² Equivalent area ventilator is fitted in each habitable room.
The minimum number of ventilators used should be: Number of bedrooms +2
e. a 2 bed dwelling would require a minimum of 4 ventilators ( 1 in each bedroom and two in the living room).

MVHR

No ventilator requirements needed.

Work on Existing Buildings

All Work except that covered in Category A will result in reduced Ventilation.
For categories B & C additional ventilation will be required.
Category C will result in significant reduction in ventilation.

Basically if you are replacing more than 30% of the windows you will be in category B or C and ventilation to the correct standard will be required

3.14

If replacing windows with background ventilators, then the windows should have ventilators not smaller than the original, and these should be controllable by the occupant.

If you do not know the size of the original window then:

3.15

Replacing existing windows without background ventilators.

Replacement dwellings without MVHR should have:
8000mm² EA in habitable rooms.
8000mm² EA in Kitchens.
4000mm² EA in bathrooms.
If the dwelling has CMEV then 4000mm² EA should be fitted in replacement windows that are not in wet rooms.
If it is not technically feasible to meet this then vents fitted should be as close as possible to the EA required.

(when replacing windows that already have vents fitted it would be recommended to record the sizes of these for the replacement windows, otherwise the vents that are sized as per 3.15 will have to be used).

Addition of a Habitable room

If the additional room connects to a room that no longer has windows:

The existing room had ventilation of less than 5000 mm² then the new room will require background ventilation of 10,000 mm².
The existing room has a background ventilation of at least 5000 mm² the new room will acquire 12,000 mm² plus 12,000 mm² between old and new room.
Conservatory will require 10,000 mm²,
Additional wet room will require 5000 mm² extra added to habitable room ventilation.

Refurbishing kitchen or bath

It is not required to add one if no ventilation system was present, unless the work being carried out is likely to reduce the ventilation.

Please note that this is Brookvent guidance. Please ensure you are reading the new building regulations regularly to understand what is required.

We are on hand to help you. If you need guidance on the correct requirements, please get in touch. Email hello@brookvent.co.uk | Telephone 028 90616505

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