Regulations: Background Ventilation in England & Wales

Introduction

The provision of background ventilation via through-wall ventilators and window trickle ventilators is a cost-effective, non-mechanical means of introducing fresh outside air into habitable rooms.  Easy to operate and fully controllable, natural background ventilators dilute and remove airborne pollutants (including odours) from rooms and control moisture to reduce the risk of mould growths which can be a health hazard to the occupants.

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  • In England, a 2021 update takes effect on 15 June 2022.  It does not apply to work subject to a building notice, full plans application or initial notice submitted before that date, provided the work for each building is started before 15 June 2023.  Both the 2010 and 2021 regulations are outlined below.
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  • In Wales, a 2022 update takes effect on 23 November 2022.  It does not apply to work subject to a building notice, full plans application or initial notice submitted before that date, provided the work for each building is started before 23 November 2023.  Both the 2010 and 2022 regulations are outlined below.
Extracts from The Building Regulations Approved Document F: Means of Ventilation in Dwellings
(2010 edition incorporating 2013 amendments)
  • For detailed guidance, refer to the full Approved Documents for England and Wales.
Natural ventilation with background ventilators and intermittent extract fans (System 1)

General notes:

  • Background ventilators should be located in all rooms with external walls.  Once the total requirement has been calculated, at least 5000mm² equivalent area is required in each habitable room and 2500mm² equivalent area is required in each wet room.
  • Promote cross-ventilation with background ventilation of a similar area on each façade, where possible.
  • Position background ventilators at least 1.7m above floor level to reduce draughts but still be accessible by the occupant.  Note: Background ventilators should normally be left open.

Make a System 1 calculation:

Total Floor Area (m2):   
Dwelling Type:    Single-storey located up to and including the fourth storey above ground level
Multi-storey, and single-storey located more than four storeys above ground level
No. of Bedrooms:   
Design Air Permeability:    Type A: Any design air permeability
Type B: Design air permeability leakier than 5m3/h.m2 at 50 Pa
Facades:    Single facade (one exposed facade only)
Multiple facades (two or more exposed facades)
    
Results

Background ventilators for continuous mechanical extract ventilation (System 3)

For any design air permeability, provide controllable background ventilation with a minimum equivalent area of 2500mm² in each room, except wet rooms, from which air is extracted.  Where the designed air permeability is leakier than 5m³/(h·m2) at 50 Pa background ventilation is not necessary.

2021 / 2022 Update
Extracts from The Building Regulations Approved Document F: Means of Ventilation in Dwellings
  • For detailed guidance, refer to the full Approved Documents for England and Wales.
Natural ventilation with background ventilators and intermittent extract fans (previously System 1)

General notes:

  • The guidance is only for less airtight dwellings i.e. dwellings with a design air permeability higher than 5m³/(h·m2) at 50 Pa or dwellings with an as-built air permeability higher than 3m³/(h·m2) at 50 Pa.
  • Install background ventilators in all rooms with external walls.  The minimum total equivalent area of background ventilators required in each room is given in the table below.
  • Provide a minimum of five ventilators in a dwelling with more than one bedroom and a minimum of four ventilators in a dwelling with just one bedroom.
  • If the dwelling has an open-plan kitchen and living room, provide at least three ventilators of the same area as other habitable rooms, in the open-plan space.
  • Promote cross-ventilation with background ventilation of a similar area on each façade, where possible.
  • Position background ventilators at least 1.7m above floor level to reduce draughts but still be accessible by the occupant.  Note: Background ventilators should normally be left open.
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Background ventilators for continuous mechanical extract ventilation (previously System 3)

Where continuous mechanical extract ventilation is used, provide a minimum equivalent area of 4000mm² for each habitable room (excluding wet rooms i.e. kitchen, utility room and bathroom).  Install the same number of ventilators as there are bedrooms, plus two ventilators (i.e. a one bedroom dwelling should have three background ventilators, a two bedroom dwelling should have four background ventilators, etc.).

Rytons Background Ventilation Range

Achieve compliant background ventilation in habitable rooms with Rytons controllable through-wall background ventilators or a combination of window trickle vents and through-wall sets.  We are always happy to assist you with ventilation calculations and product selection; call our technical sales office on 01536 511874 for advice.

Rytons Through-wall Background Ventilation Sets
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Rytons Window Trickle Ventilators
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