Introduction

This year a new version of Approved Document F relating to ventilation is coming into force. The 2022 changes to Part F will cover all building work. Volume 1 is for dwellings and Volume 2 is for buildings other than dwellings.

In this video, we'll look at Volume 2 for non-domestic buildings.

Now note that although Volume 2 does not cover dwellings it does cover buildings containing rooms used for non-dwelling residential purposes. For example, hotels hostels halls of residence and boarding houses.

Both volumes have been updated in response to the significant changes within the 2022 edition of Part L conservation of energy.

CO2 Monitors

Some occupiable spaces in new buildings will require means of monitoring indoor air quality. These spaces include rooms that are in offices where singing, loud speech, aerobic exercise or other aerosol-generating activities are likely to take place. Where members of the public are likely to gather or where both low temperature and low humidity are being maintained.

Monitoring is not required if the room is less than 125 cubic meters in volume or 50 square meters in floor area or over 800 cubic meters in volume or over 320 square meters in floor area.

Where monitors are required these should be non-dispersive infrared or NDIR Type CO2 monitors and they must be mains operated at breathing height away from windows and ventilated openings and placed at least 500 millimetres away from where people are likely to sit.

Offices

In offices, special guidance is provided mechanically. Extract ventilation will be required in toilets, kitchens, shower rooms and printer photocopier rooms.

As in previous editions of Part F, no guidance is provided about the size of opening windows for natural ventilation. However, a reasonable level of natural ventilation would be 1/20th or 5% of the room's floor area as an openable window.

The maximum depth of the room from an openable window will be 7.5 meters for a single ventilated facade and 15 meters where cross-ventilation is possible.

Common areas such as corridors should have 1/50th of the floor area as an openable window, this is a major change.

As an alternative mechanical ventilation can be installed but it must supply outdoor air at 0.5 litres per second per square meter of the floor area of the common space.

Other Non-Domestic

For other non-domestic buildings guidance within CIBSE Guide A should generally be followed.

Very little guidance on natural ventilation solutions is provided apart from CIBSE Guide AM10, which is of limited use for small-scale buildings. Some types of buildings have specialist guidance for example Building Bulletin 101 for schools and educational buildings.

Mechanical Ventilation

For mechanical ventilation systems, the guidance within CIBSE Guide A should be followed. This guide provides tables detailing recommended supply and extract ventilation rates.

In offices, mechanical ventilation must supply outside air at the rate of either:

• 10 litres per second per person or
• 1 litre per second per square meter of floor area
• 
  

Whichever is the highest.

For corridors in offices, mechanical ventilation must apply 0.5 litres per second per square meter of floor area.

Recirculation of Air

Where mechanical ventilation systems recirculate air for example air handling units either the system should incorporate:

• A UV-C germicidal irradiation system that is able to disinfect the air that is being recirculated or
• They should be designed so they can incorporate HEPA Filters

Car Park Ventilation

There are updated requirements for the ventilation of car parks.

Naturally ventilated openings should be provided that have a minimum aggregate area of

• 120th or 5% at the floor area at each level of the car park and
• have a minimum of 25% of the aggregate area on each of the two opposing walls.

Mixed ventilation can be used with 1/40th of the floor area and 3 air changes per hour increase to 10 air changes per hour at places where cars may queue.

Mechanical supply and extract ventilation is also permitted in car parks this should be at 6 air changes per hour with an increase to 10 air changes per hour at places where cars may queue.

Inlet & Extract Locations

For mechanical systems, guidance is provided on the siting of external inlets and extract grills.

They should be positioned to avoid

• Direct impact from sources of local pollution
• Be away from busy urban roads and enclosed urban spaces where air pollutants may discharge
• Be away from exhaust vents courtyards enclosures and architectural screens.

Interaction with other Parts of the Building regulations

The new Part F also includes details of interactions with other approved documents. This is to avoid the risk of silos where the building meets one part but contravenes another part of the building regulations. This is a response to the criticism within the Hackett Report

Guidance within Parts F and L includes notes about

• Ducts passing through far-resisting construction
• Manual controls of openable windows
• Protection from falling
• Risk of inter interstitial condensation
• Sound transfer on party walls
• Height and manual controls for HVAC and lighting systems
• A reference that Part O of the building regulations may require a higher standard than Part F

Transitional Provisions

Transitional provisions apply to this document. To use the old version of Part F an application must be received before 15th June 2022 and work must start on site before 15th June 2023.

Multiple buildings on an application work on each unit must have commenced for the transitional provisions to apply.

For example, on an application for 10 buildings the application must be submitted by the 15th of June 2022 and work on all 10 buildings must commence by the 15th of June 2023. If only 5 of these buildings have started then only these can be built to the old standard and the remainder must be the new 2022 Part F.