With buildings becoming increasingly airtight, Vent-Axia has welcomed the latest Approved Document Part F (Means of Ventilation) and Part L (Conservation of Fuel and Power) of the Building Regulations. The strengthened focus on competency within the updated guidance recognises how good ventilation design plays an essential role in delivering safer homes.
Part F outlines how greater care should be taken when installing a ventilation system, particularly centralised options. Compliance with the Building Regulations must be demonstrated using one of two routes – self-certification by a registered competent person or certification by a building control body. When an installer is not a registered competent person, Part F gives clear guidance on how to obtain sign-off through building control.
In addition, Part F introduces guidance that those commissioning and testing mechanical ventilation (MEV) systems should also be trained and be a member of an organisation that independently verifies their competence. For ventilation installers, these amendments offer a clear incentive to register with a competent person scheme.
There is also increased emphasis on system design, including the need to consider airflow performance and resistance in ductwork. The addition of maximum pressure figures for mechanical ventilation and mechanical ventilation with heat recovery (MVHR) systems, depending on flow rates, means that designers need to look carefully at each design and ensure pressure calculations are completed. These amendments will help improve the overall design of ventilation systems and support the uptake of lower specific fan power (SFP) solutions, as well as more advanced systems such as MVHR.
Part L also introduces tighter SFP targets across ventilation, supporting improved energy efficiency. Intermittent fans remain at 0.5 W/l/s, while MEV is now split between decentralised mechanical ventilation (dMEV) and centralised MEV, with dMEV at 0.3 W/l/s and MEV at 0.5 W/l/s for new build. MVHR systems are reduced to 1.4 W/l/s for new build.
Furthermore, Part F also brings changes to ducting, with a further shift away from flexible ductwork. For continuous MEV or MVHR the guidance states that rigid or smooth semi-rigid ducting should be used. For intermittent extract fans or dMEV rigid ducting should be used with duct lengths kept to a maximum of 2m where possible. Where duct runs exceed 2 m, a competent person must provide detailed design calculations and drawings to building control to show that the required airflows are achieved.
Joe Brawn, Product and Marketing Director at Vent-Axia, said:
“We are committed to both a low carbon future and the health and wellbeing of people. We therefore welcome the new focus on competency, the drive for better system design, and improvements in specific fan power within Part F. As carbon targets rise and homes become more airtight, it will become even more important to ensure ventilation systems are correctly designed, installed and commissioned to ensure good indoor air quality.”
Contributors
Rob Shepherd (author)
Rob is Consulting Editor for InstallerELECTRIC. He is a well-respected journalist with a strong history in the electrical sector.
