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Part F proposals emphasise inspections

There will be a requirement for all ventilation systems - natural and mechanical – to be inspected and commissioned if proposals in the current Part F (ventilation) consultation are passed.

Ronnie George (pictured), managing director at ventilation manufacturer Vent-Axia predicted the proposals would transform the ventilation sector.

'They recognise the contribution that ventilation equipment with energy efficient DC motors can make in reducing fuel consumption, both in new, airtight properties and in retrofit projects,' he said.

“They will reward those forward-thinking companies who are already ahead of the game in developing technologies that meet or exceed these new demands and help reduce a building’s carbon footprint.”

Closely tied with Part L, Part F comprises a number of significant proposed changes including:

- For mechanical ventilation systems installed in new dwellings, air flow rates shall be measured on-site as part of the commissioning process. This shall apply to intermittently-used extract fans and cooker hoods, as well as continuously running systems.

- Where continuously running ventilation systems for dwellings are specified, these shall have been type tested and shown to meet specified noise limits.

- The owner/occupier shall be given sufficient information about the ventilation system and its maintenance requirements so that the ventilation system can be operated to provide adequate air flow. This should apply to natural and mechanical systems in new dwellings.

- A check list shall be completed and given to the building control body as evidence that all the above have been done for new dwellings.

- Domestic ventilation systems will become a controlled service for ventilation as well as energy performance, which means that all work on domestic ventilation systems will be building work that must meet Requirement F1. However, only the provision (which includes replacement) or alteration of continuously running mechanical systems will be notifiable building work.

- Guidance has now been included for airtight homes. In all cases, this results in greater ventilation provisions for dwellings with design air permeability tighter than or equal to 5 m3/(h.m2) at 50 Pa.

- The infiltration allowance for leakier homes is now the same for single-storey and multi-storey dwellings, resulting in increased ventilation provisions for single-storey dwellings up to four storeys above the ground.

- For passive stack ventilators (PSV), the stack diameter has been increased to 125 mm for all room types. Use of PSV in inner wet rooms has been clarified.

Bob Towse, head of technical and safety at the HVCA said the revisions to Part F were very significant as increasingly airtight buildings needed good ventilation.

“Part F will be key in years to come as domestic buildings must have more effective control of airflow,” he said.

However, he sounded a note of concern.

“Domestic housebuilders generally don't have the ventilation skills needed and we don’t see them using HVCA members for installations. Some of the ventilation work we've seen recently has been very poor.”