Changes to Building Regulations Part F 2021 in Summary

What is building regulations part F?

Building regulations Part F is changing in June 2022 and being prepared will mean that you will comply now, and after the change.

Gradual improvements in the thermal performance and air tightness of buildings has improved thermal comfort whilst, reducing energy consumption.

However, this has increased the amount of internal air pollutants within a home

• Moisture (condensation / mould growth)
• Carbon monoxide
• Allergens (dust mites)
• Odours
• Carbon dioxide

All can adversely affect air quality and the occupant's health unless the correct amount of ventilation is provided.

Therefore, a greater importance is placed on:- “Build Tight – Ventilate Right”

Summery of current Part F

Part F defines four methods of ventilation

• System 1, Background ventilators & intermittent extract fans
• System 2, Passive stack ventilation
• System 3, Continuous mechanical extract
• System 4, Continuous mechanical supply and extract with heat recovery
• Requirement to calculate total equivalent ventilator area via matrix

– Number of Bedrooms vs Total Floor Area

• PIV (Positive Input Ventilation) is provisioned for assuming BCB certified with a BBA Certificate

Summery of key upcoming changes

Part F will reduce the ventilation strategy to a combination of:

1. Extract ventilation from wet rooms, be either intermittent or continuously running systems
2. Whole dwelling ventilation to provide fresh air to dilute pollutants, either mechanically or via background ventilators
3. Purge ventilation to remove high concentrations of pollutants and water vapor

This is in an effort to simplify the regs and make them easier to design and implement.

• Requirement to calculate total equivalent ventilator area on a room-by-room basis
• PIV (Positive Input Ventilation) is not provisioned for unless BCB certified with a BBA Certificate
• Buildings which achieve an air tightness score of 3 or less, are considered highly airtight and will require a continuously running mechanical extract system

Equivalent area ventilators new matrix

Intermittent Extract Flow Rates (System 1)

Continuous Extract Flow Rates (System 3/4)

Dwelling Ventilation Targets (System 4)