Domestic Ventilation Inspection, Commissioning and Air-flow Testing

Ventilation testing is a crucial requirement to ensure compliance with Part F of The Building Regulations. As homes become increasingly airtight to enhance energy efficiency, proper air flow is vital. Ventilation serves the primary purpose of replacing polluted or stagnant indoor air with fresh air. With improved construction standards, increased insulation, and reduced air leakage, pollutants can accumulate, posing potential harm to both the building and its occupants. Efficient ventilation systems are essential to reduce these pollutants, which can vary significantly in industrial and commercial properties compared to domestic ones.

What is Ventilation?

Ventilation in a building is the controlled supply and removal of air from spaces. Ventilation is required for several reasons:

1. To provide outside ‘fresh’ air for improved indoor air quality and to an extreme extent, for breathing

2. To dilute and remove pollutants in the air, including odours and moisture

3. To control excess humidity, particularly in rooms such as bathrooms and kitchens, and to an extent manage temperature

In domestic settings, moisture is a significant pollutant, with the average family producing about 6 liters of moisture per day. This moisture promotes mould growth and can affect the health of occupants. Part F of the Building Regulations (2010) introduced the requirement to test the practical performance of ventilation systems in new dwellings.

Ventilation testing ensures a balance between airtightness, energy efficiency, and proper air exchange, creating a healthier living environment. In addition to Part F, various other building regulations, such as Approved Document A (Structural Safety), Approved Document B (Fire Safety), Approved Document J (Combustion appliances and fuel storage systems), Approved Document L1A (Conservation of fuel and power for new dwellings), and Approved Document M (Access to and use of buildings), must be considered when dealing with ventilation systems.

Ventilation testing encompasses air-flow testing for extractor fans, often found in toilets, bathrooms, and kitchens, to measure their air extraction capacity. Commissioning involves more complex ventilation systems, such as Mechanical Ventilation Heat Recovery (MVHR), which require precise balancing to ensure each room receives the correct amount of supplied or extracted air.

These tests demand the use of UKAS-calibrated equipment and must be conducted by engineers registered with a recognized scheme. Before testing, our engineers conduct a thorough pre-test inspection of the ventilation system, assessing duct runs, terminals, and functionality. Building Compliance Testing offers comprehensive services from design reviews to site inspections, pretesting, diagnostics, site management, training, and education, ensuring that ventilation systems meet the necessary standards and regulations.

The Four Types of Ventilation Systems in Dwellings

Before conducting a ventilation test, it is crucial to identify the type of system in place, with four main categories:

System 1 – Intermittent Extract Fans and Background Ventilators

In this type of decentralised ventilation system, extract fans serve wet rooms such as kitchens, bathrooms and utility rooms, providing rapid intermittent air extraction. This fulls ‘fresh air’ through background ventilation in form of air-bricks and window trickle vents.

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System 2 – Passive Stack Ventilation (PSV)*

*Ventilation System 2 does not require testing as it relies on natural convection and draughts to exchange air within the dwelling. It should be noted that from 2010 passive stack ventilation is no longer considered an approved ventilation system. At Building Compliance Testing we do not recommend installing passive stack ventilation.

System 3 – Continuous Mechanical Extract Ventilation (MEV)

This type of ventilation system extracts air from wet rooms such as kitchens, bathrooms and utility rooms – but runs continuously a low fan speeds. The replacement air is provided by means of background ventilators. The system can be either a centralised system, comprising a single fan ducted to several rooms, known as CMEV. Alternatively, a decentralised systems can be used where individual fans extract air from wet rooms in the same manner as a System 1, known as DMEV.

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System 4 – Continuous Balanced Mechanical Ventilation and Heat Recovery (MVHR)

MVHR is a type of centralised ventilation system that combines supply and extract ventilation in one system. Typically, warm moist air is extracted from wet rooms and passed through a heat exchanger before exhausting outside. The supply ‘fresh’ air from outside then benefits from pre-heating before entering rooms such as living rooms and bedrooms.

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Vent Air-flow Testing Procedure

The assessment of ventilation is carried out using an anemometer, measuring air flow rates in litres per second (l/s). Different rooms require varying flow rates based on their purpose and the equipment they contain. For instance, a toilet typically needs an intermittent extract ventilation rate of 6 l/s, while a kitchen without a cooker hood may require 60 l/s. An office space with a photocopier might necessitate an extract rate of 20 l/s.

A certificate is generated, detailing the Air Flow Rate, which can be submitted to building control as part of the overall building compliance process.

Ventilation tests conducted by Building Compliance Testing employ UKAS-calibrated equipment and are overseen by engineers registered with a recognised scheme. All Building Compliance Testing engineers have successfully completed the NICEIC Domestic Ventilation System Course.

The tests must be undertaken using UKAS calibrated equipment and should be conducted by an engineer registered with a competent scheme.

Our Engineers will always carry out a pre-test inspection of the ventilation system, including duct runs, terminals and test all functionalities.

design reviews – site inspections – pretesting – diagnostics – site management training and education