not sure about a "certified, engineer" but I think you may need someone to "certify it" to get building regs sign off

We got a supply and certify deal with ours, where the supplier came out after we installed it and set it up to meet BC parameters (measured air flow etc) and provided paperwork for BC approval.

Not sure if you can DIY this, you may be able to hire or buy the equipment and create your own certificate..

I was hoping to keep things simple as the 'house' is 7x4.6m and only has a bathroom, a bedroom and an open plan living space.

So if MVHR is notifiable, would an extract fan in the bathroom and a cooker hood venting outside be the cheapest non-notifiable option?

Just googled this again. i thought the rule was that they needed to be commissioned by a "competent person" and somewhere I've saved a link to a template/checklist for commissioning. I wonder if you'd get away with hiring a meter, completing the checklist and signing it off.

Suppliers like Airflow will design system for free so you should only need to show it's been installed as designed. (Could it even be something you demonstrate to the BCO when they inspect?)


My first result from google just now suggests that extractor Fans also now need to be 'commissioned' -
Part F Building Regulations also requires standard intermittent extractor fans in new buildings (such as bathroom and kitchen extractors) to have their air flow rates measured on site and the results submitted to the building control body prior to completion.

http://mesbuildingsolutions.co.uk/building-regulations/air-flow-rate-testing-commissioning-of-ventilation-systems/