At Quiet-Vent, we work with housebuilders, contractors, and merchants across the UK supplying ventilation systems for both new build and retrofit projects. Part F compliance is at the centre of almost every conversation we have. This guide explains what it requires, what changed in 2021, and how it affects the systems you specify or stock.

What Is Part F of the Building Regulations?

Part F is the section of the Building Regulations 2010 that governs ventilation in buildings. It is published as Approved Document F, which comes in two volumes:

• Volume 1 Dwellings
• Volume 2 Buildings other than dwellings

The core requirement is straightforward. Part F1(1) states: "There shall be adequate means of ventilation provided for people in the building."

In practice, that means any building must have ventilation that:

• Extracts water vapour and indoor air pollutants from kitchens, bathrooms, and utility rooms before they spread.
• Supplies a minimum level of outdoor air for occupants' health on a whole-building basis.
• Purges indoor pollutants rapidly when needed  for example, after cooking or painting.
• Minimises the entry of external pollutants into the building.

Part F is linked directly to Part L (Conservation of Fuel and Power). As Part L pushes buildings toward greater airtightness to reduce heat loss, the natural ventilation that older buildings relied on disappears  and Part F requires a proper mechanical system to replace it.

Introduction of the 'Specific Fan Power' limit 

All mechanical ventilation systems must meet a specific fan power (SFP) limit. MVHR units must also meet a minimum heat recovery efficiency (typically 73%+ for Part F compliance, with most quality units achieving 85–92%).

The Four Ventilation Systems Recognised Under Part F

Approved Document F Volume 1 recognises four whole-house ventilation strategies, referred to as Systems 1 to 4:

System 1  Background Ventilators and Intermittent Extract Fans (Natural Ventilation)

Trickle vents in windows plus intermittent bathroom and kitchen extract fans. Only suitable for less airtight dwellings (air permeability above 5m³/(h·m²) at 50Pa). Increasingly limited in application as new builds become more airtight.

System 2  Passive Stack Ventilation (PSV)

Natural extract through passive stacks (ducts relying on thermal buoyancy and wind effect), with background ventilators for fresh air supply. Rarely specified in modern new builds.

System 3  Continuous Mechanical Extract Ventilation (MEV or dMEV)

A central continuously running fan (MEV) or decentralised fans in each wet room (dMEV) extracts air throughout the building. Fresh air enters through trickle vents or background 

ventilators. Suitable for highly airtight dwellings. The most widely installed system in volume new build housing.

System 4  Mechanical Ventilation with Heat Recovery (MVHR)

A central unit supplies and extracts air simultaneously, recovering heat from the outgoing air stream. Suitable for any level of airtightness. Required or strongly preferred on higher-specification builds, Passivhaus projects, and any development targeting strong EPC ratings under Part L.

Note: Positive Input Ventilation (PIV) is not listed as a Part F-compliant system for new dwellings. It is, however, widely used as a remedial ventilation solution in existing dwellings under Part F Section 3 guidance for work on existing buildings.

Part F System Comparison Table

Part F Requirements: New Builds vs Existing Dwellings

Part F applies differently depending on whether work is on a new build or an existing dwelling.

New Builds

For new dwellings, the full requirements of Approved Document F Volume 1 apply. This means:

• A compliant whole-house ventilation system (System 1–4) must be designed, installed, and commissioned.
• Airflow rates must meet the minimum standards specified in the document.
• The system must be tested and documented.
• A Home User Guide must be provided.
• If the building is highly airtight (≤5m³/(h·m²)), a continuous mechanical system (System 3 or 4) is required.

Work on Existing Dwellings

Section 3 of Approved Document F applies to material changes and replacement ventilation systems in existing buildings. The requirements are less prescriptive, but the principle remains: any new or replacement ventilation system must not make ventilation provision worse  and ideally should improve it.

This is the section that governs:

• Replacement extractor fans
• PIV installations for condensation control
• MEV upgrades from individual intermittent fans
• MVHR retrofits where whole-building fabric upgrades are occurring

Importantly, when replacing windows, if the original windows had trickle ventilators, the replacement must also include them  unless a whole-house mechanical ventilation system is already in place.

Commissioning and Handover Obligations

The 2021 edition significantly tightened commissioning and handover requirements. These are among the most commonly overlooked aspects of Part F compliance.

What must be done:

Commissioning All mechanical ventilation systems (MEV, dMEV, MVHR) must be commissioned to achieve the specified airflow rates. This means adjusting fan speeds and terminal settings until flow rates match the design specification.

Testing and documentation Commissioning results must be recorded. A commissioning notice must be submitted to the relevant building control body within five days of completion. The notice should cover both Part F and Part L requirements.

Home User Guide A non-technical guide for the building occupant must be provided at handover. It must cover:

• How the system operates
• How to use the controls
• Maintenance requirements (filter replacement schedules, cleaning)
• What to do if there are problems

For merchants and distributors: commissioning equipment  particularly air flow meters  is now a standard requirement on any new build ventilation project. If you're supplying MVHR or MEV to installers and not stocking test equipment alongside it, you're missing part of the sale.

Part F and the Future Homes Standard

The Future Homes Standard (FHS) represents the next major step in building performance regulation. Legislation is expected to be in place by December 2026, with a transition period extending to December 2027 after which all new homes in England must comply.

What the FHS means for ventilation:

The FHS requires new homes to produce 75–80% fewer carbon emissions than homes built under 2013 regulations. Achieving this requires buildings that are substantially more airtight than current standards  which in turn makes continuous mechanical ventilation mandatory on virtually all new homes.

Under the notional building specifications for FHS compliance:

• MVHR is the preferred ventilation strategy for the most energy-efficient specification route.
• MEV remains compliant but delivers less favourable energy performance in the modelling.
• Natural ventilation (System 1) is unlikely to meet FHS requirements in most new builds.
• PIV remains limited to existing building remediation.

The FHS also strengthens the requirement for indoor air quality monitoring, with specific guidance on CO₂ and humidity sensing in certain building types  an area where controls and sensor accessories will see growing demand.

For builders and merchants, the direction is clear: MVHR and MEV will dominate new build ventilation specification from 2026 onwards. The time to build product knowledge, supplier relationships, and stocked ranges is now, not under pressure after the regulations take effect.

Does Part F Apply in Scotland, Wales, and Northern Ireland?

No. Approved Document F applies in England only.

Each devolved nation has equivalent but separate ventilation standards:

For contractors and merchants operating across borders, it's important to confirm which national standard applies to any given project. A Passivhaus project in Edinburgh is governed by Scottish Building Standards, not Approved Document F.

What Merchants and Builders Need to Stock for Part F Compliance

Specifiers and installers working to Part F will need:

For MVHR (System 4):

• MVHR unit (with minimum 73% heat recovery efficiency for Part F; quality units 85–92%)
• Semi-rigid radial ductwork  dominant format for residential installs
• Rigid ductwork runs  for main branches and longer sections
• Internal air valves  supply and extract
• External weatherproof grilles  Part F requires weatherproof external terminations
• Silencers and insulation  acoustic and thermal performance
• Air flow meter / commissioning equipment  mandatory for Part F sign-off
• Replacement filter stock  mandatory maintenance; Part F-driven repeat purchase

For MEV (System 3):

• MEV central fan unit
• Extract ductwork
• Internal extract valves
• External grilles (weatherproof)
• Trickle vent components (background ventilators for fresh air supply)
• Air flow meter for commissioning

For dMEV (also System 3):

• Individual continuously running fan units per wet room
• Suitable for smaller developments or flats

Frequently Asked Question

Summary

Part F of the Building Regulations sets the mandatory ventilation standard for all new and significantly renovated buildings in England. The 2021 update raised the bar considerably  higher flow rates, airtightness-triggered system selection, mandatory commissioning, and new handover obligations.

For builders and specifiers, the practical implications are:

• Airtight new builds require continuous mechanical ventilation  MEV or MVHR.
• Commissioning is mandatory and must be documented.
• The Home User Guide must be provided at handover.
• PIV is for existing buildings only, not new build compliance.

For merchants and distributors, Part F is the regulatory engine driving demand for MVHR and MEV systems, ductwork, valves, grilles, commissioning equipment, and filter stock. The Future Homes Standard will accelerate that demand from 2026.

Ready to Stock the Right Range for Part F Projects?

Quiet-Vent supplies the full range of Part F-compliant ventilation systems  MVHR, MEV, semi-rigid radial ductwork, air valves, external grilles, commissioning meters, and filter stock  from a single UK supplier.

Whether you're a builder specifying systems for a new development or a merchant building a trade ventilation range, we can help. Request a design consultation or download our product catalogue.