Builder puts vents in an airtight house. Concerned about quality of ventilation

[maccers_85]

Looking for some advice or insight from anyone familiar with Irish Building Regulations (Part F) and ventilation systems.

We’ve got a newly built airtight house (low air permeability) with a demand-controlled ventilation (DCV) system installed. The DCV extract units are in the kitchen and bathrooms downstairs. There are wall vents in each upstairs bedroom, but these are just simple background vents — there’s no mechanical supply to those rooms.

From what I understand, in airtight houses you can’t rely solely on background vents to meet fresh air requirements, and each habitable room should have the required airflow either from mechanical supply or adequate natural ventilation.

Does anyone know:

Is this setup likely to comply with Part F for airtight dwellings?

Do the background vents upstairs meet the requirement, or should there be a mechanical supply to those rooms?



Thanks in advance for any guidance or experiences.

 

[Blackrock1]

I have an a rated house with the same set up it's not what I'd choose but I assume it meets the requirements!

 

[Micks'r]

You mention a DCV system.
The wall vents in such a system generally have an automatic valve which opens and closes depending in the internal conditions. The mechanical extraction rate of the 'wetrooms' (those rooms with a sink generally) also varies in sync with the wall vents.
Perhaps you are thinking of MVHR systems which generally also have a dedicated mechanical supply to the non-wetrooms.
For an airtight house (you don't give the level achieved?) DCV is fine but MVHR would generally be better but more costly.

 

[Micks'r]

To answer your specific question, your DCV system is likely in compliance with partF of the bRegs

 

[Alkers86]

As above, even though the extracts are ktichen and bathrooms, they are intended to draw fresh air in through the vents in the other rooms.

I don't have access now but you should have circa 1.5cm of a gap beneath internal doors to allow airflow even when doors are closed.

 

[nephster]

Just a couple of points about the passive Aereco vents you posted the image of...
There is a wheel underneath that can be set to fully closed (you don't want that), fully open (ditto) or, in the middle - open based on humidity (I think). You should be able to feel the air coming into the room. As said by those above, the active ones will draw in air via this route as needed, assuming the whole thing has been set up correctly. We had ours done as a full deep retrofit, so the active ones were tested (and a slight problem then fixed) as part of of the system being commissioned. A cert was then issued to state the ventilation system had been validated.
Make sure the transit plastic film has been taken off the small holes! Our builders left it on.
The fascia can be turned 45 degrees and removed to clean inside. Slightly different to the active ones in you wet ones, where IIRC it pulls straight off to clean.