Intermittent Extract Ventilation

Intermittent Extract Ventilation Explained

Intermittent Extract Ventilation, IEV for short, is a critical component of building regulations in the UK, specifically outlined in Part F. This ventilation system is strategically designed to periodically refresh air in designated areas like bathrooms and kitchens, ensuring optimal indoor air quality. Here’s a comprehensive overview tailored for building compliance:

Understanding the Purpose of IEV

Intermittent extract ventilation plays a vital role in maintaining indoor air quality and controlling humidity levels. This is crucial for the health and comfort of occupants, as well as for preventing issues such as mold growth and condensation.

Requirement for Inspection

Part F mandates proper installation and maintenance of intermittent extract ventilation systems to guarantee their effectiveness. Regular inspections are essential to verify compliance and performance standards.

Air-Flow Testing and Reporting

Air-flow testing is a fundamental aspect of ensuring compliance with building regulations. This involves measuring air flow rates to confirm adherence to minimum standards. Qualified professionals employ specialized equipment for accurate testing.

IEV Compliance

Reports generated from air-flow testing provide detailed insights into system performance, including compliance with prescribed ventilation rates outlined in Part F. This ensures that ventilation systems meet or exceed minimum requirements.

Complying with Part F: IEV Strategies

  1. Selecting Appropriate Strategies: Identify areas necessitating IEV systems, such as kitchens and bathrooms, and choose suitable options like extractor fans with timers or humidity sensors.
  2. Design and Installation: Ensure correct design and installation of IEV systems, focusing on optimal placement and adherence to performance criteria.
  3. Air-Flow Testing: Conduct thorough air-flow testing to validate air exchange rates and efficient moisture and pollutant removal.
  4. Commissioning: Verify post-installation functionality and performance compliance with Part F standards.
  5. Timers and Sensors: Employ timers and humidity sensors as specified to ensure consistent and efficient ventilation operation.
  6. Documentation and Maintenance: Maintain comprehensive records of specifications, installation details, and testing data. Regular maintenance is crucial for sustained compliance.
  7. Consultation with Authorities: Collaborate with local building control authorities to ensure alignment with specific regulations and standards.


Adhering to Part F of the Building Regulations is paramount for maintaining indoor air quality and energy efficiency. Effective design, installation, testing, and maintenance of IEV strategies are integral components of compliance. Neglecting these requirements can lead to non-compliance and potential legal ramifications.

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