What you need to know Part F Building Regulations.

As a follow-up to our latest article, ‘Air Tightness Test Scotland: What Do You Need To Know?’ we will discuss how the industry is moving more to a Passivhaus standard of home building. It is important to understand how the building regulations across the UK manage the internal air quality and the steps you should take to provide your build with the optimum amount of fresh air to prevent mould and dampness and ensure a comfortable and healthy indoor environment.

What is Approved Document Part F of Building Regulations?

In June 2022, the Building Regulations Document F was updated to address the need for improved building ventilation. The primary aim is to ensure “adequate means of ventilation provided for people in the building.” Part F building regulations come in two parts, as with the Part L regulations. 

Approved Document F: Volume 1 applies to dwellings.

Approved Document F: Volume 2 applies to buildings other than dwellings

These documents provide detailed guidance on meeting the ventilation requirements for upcoming projects until Future Home Standard. 

The Purpose of Part F

The main focus of Part F is to improve air quality and prevent the growth of mould, which can be highly toxic and damaging to health. This has come to the forefront of national news after the passing of Awaab’s law and the focus on improving air quality nationwide. Mould and internal air pollution might become hazardous to health without adequate ventilation.

Mechanical vs Passive Ventilation

When planning a new building, you must provide the right ventilation for each room. Knowing the types of ventilation on offer allows you to make the right choice for each room in your building, whether it be a new home, an office building, or a renovation project. 

Mechanical Ventilation

Mechanical or controlled ventilation is a method of controlling the environment within a building or a space by using active means, such as fans and ductwork. It is used to provide fresh air to the building, remove stale air, and control the temperature and humidity of the air, all of which improve air quality and keeps the home healthy and comfortable. Mechanical ventilation can be applied in all building settings, from renovation through to new build residential and commercial buildings.

The main benefits of mechanical ventilation:

• It can provide ventilation to any room in a building, even those that are difficult to ventilate naturally.
• It can use a heat recovery system to keep the air in the building warmer and not introduce colder air.

The drawbacks of passive ventilation:

• Often, the ducting in a centralised system can be bulky and difficult to fit into a project design
• These systems can be expensive and often require ventilation specialists to fit. 

Passive Ventilation

Passive/Background ventilation, also known as natural or uncontrolled ventilation, relies on natural forces, such as wind and thermal buoyancy, to circulate air into and out of a building. It requires no mechanical systems or energy use.

In new builds, the most common uncontrolled ventilation systems include trickle vents in windows and doors, air bricks, and chimneys.

The main benefits of passive ventilation:

• It is a low-cost to ventilate a building.
• It can easily be retrofitted to most rooms by installing new windows with trickle vents.

The drawbacks of passive ventilation:

• An uncontrolled system relies on drafts to bring air in and out of a building, even in winter this means you are losing heat to bring in fresh air, unlike controlled systems.
• The ventilation isn’t uniform in every room, meaning you can have vastly different fresh air rates in each room at random.
• By relying on drafts, you are bringing air through any gaps and cracks in the building envelope, which can introduce dust, pollutants, and irritants into the air. 

Both mechanical and passive ventilation have their advantages and disadvantages. The best type of ventilation for a particular building will depend on several factors, such as the size of the building, the climate, and the desired level of ventilation.

Understanding Different Types of Ventilation

Three main types of ventilation are covered in Part F, each contributing to removing pollutants and maintaining air quality inside a home.

Extract Ventilation 

Extract ventilation is required in rooms with excessive moisture, such as kitchens, utility rooms, bathrooms, and toilets. The goal is to remove as much moisture and odour as possible to minimise spreading to other parts of the house.

Whole Dwelling Ventilation 

Whole-dwelling ventilation should distribute fresh air throughout the house without opening a window to disperse moisture and pollutants such as VOCs and carbon dioxide. The air distribution can be provided by a continuous supply fan or background ventilators, depending on how airtight the property is.

Purge Ventilation 

Purge ventilation is the ability to open a window or door that can allow enough fresh air directly from the outside, this is often used in summer when opening the windows and doors at night to cool the house. 

When is passive ventilation not enough?

With energy efficiency, eco-conscious and low-carbon buildings at the centre of government policy, the uncontrolled heat losses from background ventilation are being phased out. This can be seen with the push for lower air permeability rates from Building Regulations Part L, and the EPC boost that draught-free homes with mechanical ventilation systems mean that active ventilation is becoming increasingly common. This is because at below 3m3/(h.m2) @50 pa, passive ventilation solutions does not bring sufficient fresh air into the building and active (mechanical) ventilation is required. 

If you want to get as close as possible to Passivhaus standards, AeroBarrier’s test and treatment provide a simple solution that helps fill gaps in the building envelope up to 12mm wide. This simple and easy solution can help stop the need for expensive rebuilds and repair works. Speak to our team today and get a free quote.