Mechanical Ventilation Commissioning

Mechanical ventilation commissioning (also known as MVHR commissioning) verifies that your building's ventilation system is correctly set up and delivering the right supply and extract rates to every room. Incorrect airflow rates can cause dampness, mould, and poor indoor air quality over time. UK Building Compliance provides ATTMA-accredited mechanical ventilation commissioning for both residential and commercial buildings, ensuring compliance with Approved Document F and building control sign-off.

What Is Mechanical Ventilation Commissioning?

Mechanical ventilation commissioning is the process of testing, adjusting, and balancing a building's mechanical ventilation system to ensure it delivers the correct airflow rates to each room. This is most commonly required for Mechanical Ventilation with Heat Recovery (MVHR) systems, but also applies to Mechanical Extract Ventilation (MEV) and other powered ventilation systems.

MVHR systems work by extracting stale, moisture-laden air from wet rooms (kitchens, bathrooms, utilities) and supplying fresh, filtered air to habitable rooms (bedrooms, living rooms). A heat exchanger recovers warmth from the outgoing air and transfers it to the incoming supply, reducing energy consumption. For this system to work effectively, the supply and extract rates must be correctly balanced.

Commissioning involves measuring the actual airflow at each supply and extract terminal, comparing the results against the design specification and Part F requirements, and adjusting the system settings until the correct rates are achieved. Without proper commissioning, even a well-designed and installed MVHR system may fail to deliver adequate ventilation.

Why Do You Need Mechanical Ventilation Commissioning?

Compliance with Approved Document F (Part F of the Building Regulations in England and Wales) requires that all mechanical ventilation systems are properly commissioned before building control sign-off. The Building Regulations set minimum extract and supply rates for each room type, and these must be verified through on-site testing.

Without proper mechanical ventilation commissioning, a number of problems can develop over time. Under-ventilated rooms accumulate excess moisture, leading to condensation, mould growth, and potential health risks for occupants. Over-ventilated rooms waste energy and can create uncomfortable draughts. An imbalanced system — where supply and extract rates are not correctly matched — can cause pressure differentials that draw in unfiltered air through gaps in the building fabric.

As new homes are built to increasingly high airtightness standards, the role of mechanical ventilation becomes even more critical. Tight buildings rely entirely on their ventilation systems for fresh air, making correct commissioning essential for occupant health and energy efficiency.

Our Mechanical Ventilation Commissioning Process

UK Building Compliance delivers professional, ATTMA-accredited mechanical ventilation commissioning services.

1. System review — We review the ventilation system design, ductwork layout, and Part F airflow requirements for the specific dwelling to understand the target supply and extract rates for each room.
2. Pre-commissioning checks — Our engineer checks that the MVHR unit is installed correctly, ductwork is properly connected and sealed, filters are clean, and the system is powered and operational.
3. Airflow measurement — Using calibrated equipment, we measure the actual supply and extract airflow rates at each terminal in the dwelling.
4. System balancing — We adjust terminal dampers and system settings to achieve the correct airflow rates in each room, ensuring the overall supply and extract volumes are correctly balanced.
5. Energy optimisation — We optimise the system to achieve the required airflow rates with minimal electrical energy consumption, promoting long-term energy efficiency.
6. Certification — We provide an accredited commissioning certificate for building control sign-off, confirming that the system meets all Part F requirements.

What's Included

• ATTMA-accredited mechanical ventilation commissioning
• Measurement of supply and extract rates at every terminal
• System balancing and adjustment to achieve design airflow rates
• Energy optimisation for minimum electrical consumption
• Commissioning certificate for building control sign-off
• Pre-commissioning system checks
• Expert guidance on system operation and maintenance for building occupants
• Coordination with air tightness testing and ventilation testing

Who Needs Mechanical Ventilation Commissioning?

• New-build dwellings with MVHR — All homes fitted with Mechanical Ventilation with Heat Recovery systems require commissioning before building control sign-off.
• Dwellings with MEV systems — Homes with Mechanical Extract Ventilation (centralised or decentralised) also require commissioning to verify extract rates.
• Commercial buildings — Non-domestic buildings with mechanical ventilation systems require commissioning under Part F2 and Part L2A of the Building Regulations.
• Passivhaus projects — Passivhaus buildings rely heavily on MVHR systems and require particularly precise commissioning to achieve the required performance standards.
• Retrofit projects — Properties retrofitted with mechanical ventilation systems under PAS 2035 or similar schemes require commissioning to verify performance.

Housebuilders, developers, M&E contractors, architects, and self-builders all benefit from professional mechanical ventilation commissioning.

Why Choose UK Building Compliance?

UK Building Compliance provides expert mechanical ventilation commissioning carried out by ATTMA-accredited engineers with extensive experience across all major MVHR and MEV system manufacturers. We hold additional accreditations with Stroma, ABBE, BPEC, Elmhurst, and UKAS.

Our comprehensive building testing service means your MVHR commissioning can be coordinated with air tightness testing, ventilation testing, sound insulation testing, and SAP calculations — reducing the number of site visits and keeping your project on track.

Based in Hinckley, Leicestershire, we provide nationwide coverage with competitive pricing. Call us on 01455 242297 for a free quote.