# What rooms should ventilation vents be placed in?



## brokeagain (28 Oct 2011)

We are in the process of buying a house and engineer has pointed out that there are no vents in the house. The owner has asked what rooms we want the vents placed. Where are vents compulsory according to building regulations??


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## serotoninsid (28 Oct 2011)

Maybe an opportunity to install HRV (Heat Recovery Ventilation) - depending upon how 'airtight' the house actually is...?  Otherwise, maybe window trickle vents can be used instead?

I'm open to correction - but I would imagine it's all bedrooms and wetrooms that require ventilation.


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## lowCO2design (28 Oct 2011)

LiveForTheWE said:


> We are in the process of buying a house and engineer has pointed out that there are no vents in the house. The owner has asked what rooms we want the vents placed. Where are vents compulsory according to building regulations??


look here http://www.environ.ie/en/Publicatio...ng/BuildingStandards/FileDownLoad,1647,en.pdf

every room!


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## lowCO2design (28 Oct 2011)

sorry, i re read this post. your buying a second hand home, ive removed some of my post


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## CBGB (28 Oct 2011)

If its 2nd hand built in the boom house I would wager it not being the most air tight so mechanical Heat recovery ventilation would not be the best. 
Correct me if i'm wrong but the buidling regs are moving/have moved towards having no vents in the house to improve energy performance. An older house would natuarlly breath (i.e. leak) so you get natural ventilation. 
I wuoldnt agree with this view and think ventilation should be in all habitable rooms. Mechanical vents in wet rooms (bath, ensuite, kitchen). I would go with wall vents in all rooms that you can close if its very windy. Another option, which my builder recommended for our house was to put the vents in the bedrooms upstairs in the ceiling and out out through the soffit. So we get no gusts coming in and the stale air still gets out. 
As far as I've read/heard the window vents can have a negative affect on the U-value of your window.


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## onq (28 Oct 2011)

LiveForTheWE said:


> We are in the process of buying a house and engineer has pointed out that there are no vents in the house. The owner has asked what rooms we want the vents placed. Where are vents compulsory according to building regulations??



Hi 


You appear to already have an engineer appointed - you should ask him first.
If he says he is only competent to interpret and comment on Part A, appoint a competent architect and ask him to comment.
In general each habitable room requires ventilation, but you need a  comment from the person you retain who is inspecting the house

Not all houses need permanent ventilation depending on their age and whether or not an MVHR system is used.
If the house is not built to the latest sealing standards and also using MVHR, it should have permavents.

If it has a gas appliance it will need a supply of fresh air and an exhaust or a local vent/extractor.
A litre of gas produces a litre of water vapour which can build up all too easily

Open fireplaces in older properties are deemed to be sufficient to vent the room the fireplace is in.
However it was assumed that supply air for this fire is through infiltration movement within the house.
When the fire is out and the chimney is not built-in or blocked or sealed, it acts as a vent

Depending on the age of the house different regulations will apply.
These regulations have changed several times over the past twenty years.
If the work was commenced before 1st June 1992 Building Bye-Laws may apply.

NOTE: Attempts to seal older houses while not supplying vented air can be a serious risk to occupants.


ONQ

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                           as a defence or support - in and of itself -      should       legal        action    be      taken.
Competent legal and building professionals should be asked to advise in                           Real Life with rights to inspect and issue    reports    on     the         matters    at      hand.


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## lowCO2design (28 Oct 2011)

CBGB said:


> If its 2nd hand built in the boom house I would wager it not being the most air tight so mechanical Heat recovery ventilation would not be the best.


 yes, not without improvements. 


CBGB said:


> Correct me if i'm wrong but the buidling regs are moving/have moved towards having no vents in the house to improve energy performance.


 wrong, vents are still required althought for the first tmie air-tightness (uncontrolled air-leakage) has been reduced slightly


CBGB said:


> An older house would natuarlly breath (i.e. leak) so you get natural ventilation.


 i would suggest that the 'building breathing' and airleakage are to differnt things but i see where your coming from and this is a major problem where people upgrade there windows (for example) and don't consider including adequate ventilation 


CBGB said:


> Another option, which my builder recommended for our house was to put the vents in the bedrooms upstairs in the ceiling and out out through the soffit. So we get no gusts coming in and the stale air still gets out.


 this sounds a bit dodgy, ill have to check the Regs on that one..



CBGB said:


> As far as I've read/heard the window vents can have a negative affect on the U-value of your window.


 not to my knowledge, the two (heat loss and ventilation) are taking as separate things entirely. theer maybe some arguemetn that the actual vent is not sophisticated enough to incorporate a thermal break etc. but I've yet to see a window unit U-value effected by regulation required permanent ventilation.


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## tosullivan (28 Oct 2011)

All


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## brokeagain (28 Oct 2011)

Thanks for your very informative reply. The house was built in 2005 but has never been lived in so we will be the first occupants. We are getting trickle vents installed in all windows now. I would be too worried about CO2 not to have some form of ventilation.


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## onq (29 Oct 2011)

HI  

Trickle vents in windows may have been acceptable under TGD F 2002.
As against this they can fail to function well if sealed off behind heavy drapes.

This is Technical Guidance Document F 2002, which would probably be the standard required at the time.
If you would like to review the changes that have occurred in recent years, here is Technical Guidance Document F 2009.


ONQ

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                            as a defence or support - in and of itself -       should       legal        action    be      taken.
Competent legal and building professionals should be asked to advise in                            Real Life with rights to inspect and issue     reports    on     the         matters    at      hand.


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## onq (29 Oct 2011)

CBGB said:


> Another option, which my builder recommended for our house was to put the vents in the bedrooms upstairs in the ceiling and out out through the soffit.



Hi CBGB,

This isn't generally recommended.
Its hard to say definitively what the effect might be for your particular house, but I note the following.

You're venting warm air out through the insulation designed to  keep heat in.
You're venting moist air past the vapour check designed to keep water vapour out  of the attic.

With warm moist air hitting cold air and/or cold surfaces you run the risk of having a "wet" attic.

This may cause reduced effectiveness for any quilted insulation if the water condenses on it.
It may cause risk few frost forming on the inside of the roofing felt or on objects on the attic space.

Finally it may increase the moisture content of timbers forming the roof structure, which can cause twisting and cracking in extreme cases.
It may of course result in none of the above, but its as well to be aware of the potential problems and keep an eye out for them by checking your attic occasionally. 


ONQ

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                             as a defence or support - in and of itself -        should       legal        action    be      taken.
Competent legal and building professionals should be asked to advise in                             Real Life with rights to inspect and issue      reports    on     the         matters    at      hand.


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## AlbacoreA (30 Oct 2011)

How do you stop wind blowing clean through vents. A couple of mm of plastic of a closed vent is going to do nothing for keeping cold out and heat in if theres a huge whole in the wall behind it.


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## onq (30 Oct 2011)

I don't write the regs AlbacoreA 

You don't die from draughts, but you can die from lack of oxygen.
Its the lesser of two evils in relation to the old wall vents.
An illegal workaround were the old hit-and-miss vents.

I say "illegal" because the object was permanent "background" ventilation and a vent that can be sealed off doesn't supply this.
Now we're hearing waffle about on-demand vents, which sound like intermittent infiltration vents to me.
We don't seem to have moved on too far from the Georgian House after all.

We should be investing our time in -
(i) finding a cheap and affordable source of energy (hydrogen/oxygen => water cycle is the obvious one) and
(ii) dressing appropriately for the temperature and not expecting to be able to wander around in tee shirts in our houses.


ONQ

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                              as a defence or support - in and of itself -         should       legal        action    be      taken.
Competent legal and building professionals should be asked to advise in                              Real Life with rights to inspect and issue       reports    on     the         matters    at      hand.


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## AlbacoreA (30 Oct 2011)

Most of the vents I've seen installed let almost as much air (heat & cold) and out when they are closed as when they are open. They are not "sealed" in any sane use of the word. 

If the draughts are causing heat lost, thus, heating bills too expensive then someone can't afford to run it, especially older people then draughts could indeed kill someone indirectly. 

I was really wondering is there a better low cost way. Some vent with baffles or something.


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## onq (31 Oct 2011)

I'm always open to suggestions.

Its possible that the "on-demand" walls vents may satisfy some of the concerns you raised.


ONQ

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                               as a defence or support - in and of itself  -         should       legal        action    be      taken.
Competent legal and building professionals should be asked to advise in                               Real Life with rights to inspect and issue        reports    on     the         matters    at      hand.


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## AlbacoreA (31 Oct 2011)

For example?


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## onq (31 Oct 2011)

LCO2D posted comments on this in a recent thread IIRC - but you'll have to search for it.

I Googled these results

Similar conversation on boards.ie
http://www.boards.ie/vbulletin/showthread.php?t=2056412454

On-demand vents.
[broken link removed]

No connection.
This is not a representation.
I am not endorsing their use.


ONQ

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                                as a defence or support - in and of  itself  -         should       legal        action    be      taken.
Competent legal and building professionals should be asked to advise in                                Real Life with rights to inspect and issue         reports    on     the         matters    at      hand.


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## AlbacoreA (31 Oct 2011)

I'll have to inquire about them. Most houses seem to have a simple hole in the wall, then a simple plastic grill.


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## CBGB (1 Nov 2011)

onq said:


> Hi CBGB,
> 
> This isn't generally recommended.
> Its hard to say definitively what the effect might be for your particular house, but I note the following.
> ...


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## onq (1 Nov 2011)

Sounds far too ad hoc to me. I would ask a mechanical and electrical consulting engineer to comment.
Unless the pipe itself is insulated it may allow the water vapour to condense within the pipe. 
Water + air can result in bacterial infection - including [broken link removed].
Link relates to hotels with aircon systems, which may refer.


ONQ

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                                 as a defence or support - in and of   itself  -         should       legal        action    be      taken.
Competent legal and building professionals should be asked to advise in                                 Real Life with rights to inspect and  issue         reports    on     the         matters    at      hand.


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## james80 (5 Mar 2014)

Hi,
We have open chimneys in two bedrooms in our house (built c. 1950) but no wall vents. Does anyone have any idea what the best solution is for ventilation? One option I thought was best was to close up the fireplace leaving a very small hole so that the chimney can be ventilated and then to add controllable wall vent or humidity sensitive wall vents. I am assuming here that since I have closed up the fireplace except for a small hole to ventilate the chimney that this would no longer be sufficient to ventilate the room. Anyone know what the airflow in a closed up chimney is like?
Thanks.


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## chippengael (23 Apr 2014)

onq said:


> Hi
> 
> 
> A litre of gas produces a litre of water vapour which can build up all too easily


 

Actually, I think that 1 litre of methane (at standard temperature and pressure) produces 2 litres of water vapour and 1 of carbon dioxide (at STP). For every cubic metre of methane burned, 1.6 litres of liquid water is produced at standard temperature.

CH4 + 2O2 -> CO2 + 2H2O


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