'A' rated house but gaping vent holes

Oh one thing I will say is those slide vent covers are crap. Replace them with circle ones design for the hole. They are infinitely more controllable.

There was a device featured on Duncan's eco prog on Rte.

It was designed to fit in the vent pipe and act as a heat recovery unit

https://www.youtube.com/watch?v=0ofxAXPmwnM

Believe it or not there are people who never open their windows , you have no guarantee they would be used correctly. You need to provide a fool proof way of ensuring ventilation . I honestly think there is a clear link to the houses built in the 60s-80s with no ventilation and increased in asthma and respiratory disease.

You would not believe how much the air quality can deteriorate overnight in a bedroom with 2 people sleeping if there is no dedicated ventilation

How on earth does a new A rated home in 2021 not have MVHR or DCV?

Fools and their money...............

House built in the 60s-80s are not airtight.

If there is an associated increase in respiratory problems, I can't see how it would be lack of ventilation???

Yep. That was it.

You could fly a flag in most of those old houses with all the windows and doors closed.

In the winter you'd be breaking the ice on the inside of the glass. If you could feel your hands.

But you are right I've never tested them for airtightness or CO2. I'm just making assumptions based on my own experience which may be an outlier.

So you could be could be entirely right. I'd love to see any studies on it.

Thanks for the reference to "plasterboard tents" which I had never heard of; this is well worth a read:

Not sure about first question. For the second, Id generally avoid a well known UK brand beginning with A.

Terrible advice not to mention the legality of it all.

Because the vent holes are not related to heat retention, but ventilation. Without adequate ventilation, the humidity of the air within the house keeps increasing, and warmer air can hold greater levels of water content in the air. This then leads to condensation and mould within the house. You need ventilation to provide sufficient air changes.

That's why it's nonsense to suggest blocking them up or just "open a window every now and again". Air changes need to be constant to keep moisture levels in the air down. Houses nowadays are designed with both heat retention and sufficient ventilation in mind. Changing one affects the other.

When airtightness tests and BER assessments are done on houses, it's testing the airtightness through the building fabric itself. The wall vents are taped and sealed. The type and number of background ventilation such as wall vents are taken into consideration seperately.

The assessments aren't just a box ticking exercise, but are used as a design tool pre-construction as much as an analysis post-construction. You can over-specify some elements to compensate for some lower elements, however there's also still minimum specifications things have to achieve to comply with the building regulations (eg. minimum levels of ventilation, minimum airtightness, minimum insulation levels). In some regards, the BER results in some box-ticking, counting etc. But the design and specification first and foremost is done in accordance with achieving building regulations.

There is sooo much wrong with this post. Please do not heed.

I'd block them immediately, awful stupidity. But only so long as you ventilate regularly by opening windows and it doesn't hurt to have a dehumidifier too. TBH everyone should get one of those anyway.

"Far too high" based on what, though? What types of hygrothermal assessments or analysis are you basing that comment on?

If local geography is determined to be a factor, the onus for that is on the designer to address, and to perhaps look at an MVHR system instead of natural ventilation. It doesn't mean the regs are wrong. And the issue with just opening windows or using a dehumidifier is that they're not always used right by the occupants. Windows are left closed, or dehumidifiers only in one or two rooms or not turned on enough. Hell I've been in plenty of houses where even the trickle vents are left closed by the occupants (who are complaining about condensation and mould at the windows). I've taken high Relative Humidity and Dew Point readings in houses where the occupant is complaining that it's too cold.

Many owners/occupiers/tenants etc don't understand the need for ventilation or the effects of improper ventilation. They will do whatever's most comfortable or easiest at the time, and the gradual effect of that ends up being mould/condensation which they don't understand because "Sure I'm constantly opening the windows!"

As houses become more airtight and better insulated, proper ventilation strategies are more important than ever, and can rarely be left just as the owner/occupant's discretion to implement because that's rarely going to be done right. If there's deemed to be an issue with background wall vents due to local geography, then an MVHR system should be installed, and it's the designer's responsibility to establish that.

How could house be A rated with uncontrolled passive vents in the walls. It wouldn't pass an air tightness test.

I'd love to see the SEAI do another study to see how many houses are actually built to the standard they claim to be. There is almost no checking of how houses are built.

If you are self building you have to have eyes in the back of your head trying get tradesman and builders to do things to properly. I can only imagine what happens everywhere else.

But what are you testing in that case? You can't test the air permeability in the room with a wall vent open.

The airtightness test is required to determine the air permeability of the building fabric. It's seperate from how much ventilation is provided to achieve the required level of ventilation/air changes per hour, and there are different ways to achieve that (eg. wall vents, wall vents + trickle vents in windows, mechanical ventilation, mechanical ventilation & heat recovery).

One feeds the other. For example if you want to use an MVHR system, you need a better airtightness result because otherwise you're going to be losing too much through the building fabric and the MVHR system won't be able to operate efficiently.

But again, airtightness testing is measuring unintentional air infliltration through the building fabric. Background ventilation (wall vents, trickle vents) are sources of intentional air infiltration to provide the required air changes.

The external louvres on most wall vents dissipate the effects of most strong gales. But yes, again a lot of that comes down to the designer and if they feel the external air or noise levels will be factors, alternatives to wall vents should be assessed.

But that's not an excuse to block up wall vents and just say "I'll open the window every now and again." That's the issue, and I've seen it in plenty of houses where it leads to mould & condensation because the required level of air changes aren't being achieved.