Passive house - does ventilaiton sys really mean you do not have to open a window

fclauson

For over 40 years I have slept - regardless of the weather - with a window open - and now that i have children they are being treated in the same way as I was - an love it (they hate hotels etc which are airless)

How does this fit with a passive house - if you have spent your extra 10 or 20% insulating the place to the hilt and then you leave windows open - it must screw up the heating system no end.

What are the choices in this case
1 - sleep with windows closed amd trust the ven system
2 - sleep with windows open - but close doors from bedrooms
3 - or ????

In a Passive house where your have a very small back up heater how does this work if you have "intentially" cold soaked the house by having the windows open. How long would it take to bring the living quarters back to "warm"

Passive hosues sound great - but in reallity do they mean that you have to keep the windows closed in the cold weather (warm weather is obviously a different storey)

Our house has high levels of insulation and a Heat recovery ventillation system, not Pasive house standard but close.

My experience is that I find that the air in the house is always fresh, but the missus sometimes complains that it's "stuffy" on warm days, she opens windows all over the place - even on cooler days she does the same! Lets all the heat out! :mad:

If there is a large amount of thermal mass in the house and the windows are not left open for too long then the temperature will recover fairly quickly.

The real issue is how you perceive the air to be "fresh", my wifes perception is that you have to "feel it" blowing on you! The air's not cold it can't be fresh!!!! Crack that one and you'll have no problems with the windows being closed.

If you put lots of insulation between the rooms and have zoned heating and ventillation then you can get the best of both worlds, one of the issues I've found with MHVR systems is that the air flowing in is at the same temperature to all rooms.

Having the bedroom windows open at night, means that the temperature in those rooms will be lower than the rest of the house.

sydthebeat

perhaps the reason for sleeping with an open window should be investigated before questioning if its applicable to a passive house.

if the reason is to stay cool, then the heating controls should be set to achieve that.......... easily enough to do.... set stas for, say 15 deg.
if the reason is for fresh air, then the hrv system should be set so....

but it must be remembered, hrv systems need constant maintanence... monthly but at least bimonthly.

its all about control. the habit probably developed due to a lack of control of either the heating or the ventilation. if this control exists, then the reason to open the window is negated. habit are there to be broken.

the only reason windows need to be opened is for:
1. rapid ventilation
2. passive cooling
3. escape and or egress
4. cleaning

fclauson wrote: »

For over 40 years I have slept - regardless of the weather - with a window open - and now that i have children they are being treated in the same way as I was - an love it (they hate hotels etc which are airless)

How does this fit with a passive house - if you have spent your extra 10 or 20% insulating the place to the hilt and then you leave windows open - it must screw up the heating system no end.

What are the choices in this case
1 - sleep with windows closed amd trust the ven system
2 - sleep with windows open - but close doors from bedrooms
3 - or ????

In a Passive house where your have a very small back up heater how does this work if you have "intentially" cold soaked the house by having the windows open. How long would it take to bring the living quarters back to "warm"

Passive hosues sound great - but in reallity do they mean that you have to keep the windows closed in the cold weather (warm weather is obviously a different storey)

A country home

i like the idea, but i dont think i could live with not opening the window. ..

just like a car, id always have the window down.. . .could never just rely on fan/air con. . . .

I think that if one was to use HRV sys they should have a policy of not openning windows. . . .

but is this possible in ireland. .. . . we love openning windows, and and OPEN FIRE PLACES

sinnerboy

early american experience with air conditioned offices was that people perceived a lack of fresh air because they had no "sense" of it

solution - ribbons attached to ceiling vents . it worked - people could "see" the air movement

opening windows in winter in a passiv house would be a bad idea , you simply aren't supposed to

not for everyone

sinnerboy

sinnerboy wrote: »

early american experience with air conditioned offices was that people perceived a lack of fresh air because they had no "sense" of it

solution - ribbons attached to ceiling vents . it worked - people could "see" the air movement

That sounds exactly like my missus, must but some ribbins!

sydthebeat

A country home wrote: »

but is this possible in ireland. .. . . we love openning windows, and and OPEN FIRE PLACES

passive houses are not for you, then.........

sinnerboy

A country home wrote: »

just like a car, id always have the window down.. . .could never just rely on fan/air con. . . .

About 5 years ago imagine my delight - my first air conditioned car ... and a rare hot summers day

Pack the family in and off we go . Rebellious teenage daughter has a hissy fit - insisting "I WILL PUKE" if windows aren't open

Not everyone wants to trust the air they breath to a machine . That's people for you .

I started out with some enthusiasm for HRV a couple of years back , but I have less now . People don't want to live in machines . If filters are not cleaned very regularly ( max interval 2 months ) HRV not only becomes inefficient it becomes dangerous . Dust and small insect life gathers . Want to breath through that ?

Leadership

I need an airflow over my face as well to sleep, long story but basically I sleep best if I am camping out under the stars without a tent.

I am putting HRV into a very well insulated house and my plan (not tested yet) is to use a small desk fan to create the airflow to enable me to sleep.

gizmo555

sinnerboy wrote: »

I started out with some enthusiasm for HRV a couple of years back , but I have less now . People don't want to live in machines . If filters are not cleaned very regularly ( max interval 2 months ) HRV not only becomes inefficient it becomes dangerous . Dust and small insect life gathers . Want to breath through that ?

I'm new to living with HRV myself, having just had it installed about a fortnight ago. The filter cleaning you mention takes about 5 minutes from start to finish and can be done without the use of any tools, other than a vacuum cleaner. Can't see that that's any great hardship. That said, I know there are many forgetful if not plain lazy people out there (I myself have been known to be both!) All the same, all it takes is writing a reminder on the calendar hanging in the kitchen.

As for the health risks, they may exist, but there are also health risks which HRV helps to mitigate, e.g., venting products of offgassing from paint, MDF, and so on; reducing or eliminating mould growth and associated spores; keeping down dust mite populations; venting radon if it's there; etc. As I said I'm new to it, but I've a friend who has been living in a house with HRV for a few years now, who is also very asthmatic and sensitive to poor air quality - she swears by it.

Coming back to the OP's query, I used to like to sleep with an open window, but my wife was adamant she wouldn't. I always found the bedroom stuffy, even with the old window trickle vents open and had to open the windows every morning to air the room out. Since getting the HRV I find I get a better night's sleep and there is never any need to open windows for fresh air - it's already there!

sinnerboy

I freely admit that I have yet to hear of anyone who has it say anything else but that they really like it .

but take heed

http://www.greenbuildingpress.co.uk/article.php?category_id=1&page=3&article_id=213

.

CJhaughey

We have HRV since we moved in march 06, and TBH it is hard to beat, the rooms are always fresh and the house is always dry inside, low humidity due to the moisture being removed during the heat recovery process.
Cooking smells dissipate quickly, even with the extractor in use you always get some residual smell, and the house stays at an even temp over the course of a 24 hr period.
Think about the way in which a house is usually ventilated, cold windy rainy days give the most ventilation, when you don't want open windows.
Warm hot humid windless days give the least ventilation when you need it the most.
I use a floor fan on hot days to give a refreshing breeze but haven't needed it this summer:)
I love it and make no apologies for doing so.

gizmo555

Leadership wrote: »

I need an airflow over my face as well to sleep, long story but basically I sleep best if I am camping out under the stars without a tent.

I am putting HRV into a very well insulated house and my plan (not tested yet) is to use a small desk fan to create the airflow to enable me to sleep.

Have you considered locating the vent in your bedroom directly above where your bed will be?

fclauson

Hi all

thanks for all your replies - sounds like a bit of a mixed bag- the idea that the house all over is at the same temp would take some getting used to - its the STUFFY bit I am concerned about - my parents are over 80 and their house is like the north face of the Eiger - but my Dad has NEVER taken a day off sick in his life

mrgaa1

you should always re-air your house by opening windows for a period of time to allow fresh air - regardless of HRV's etc... The BER cert allows for cross-ventilation and certainly its a necessity.

gizmo555

mrgaa1 wrote: »

you should always re-air your house by opening windows for a period of time to allow fresh air - regardless of HRV's etc... The BER cert allows for cross-ventilation and certainly its a necessity.

I don't really understand this. A HRV system would be designed to completely change all the air in a house eight or more times a day. What additional point would be served by opening windows? Wouldn't you just be defeating the purpose of the HRV? Why is cross ventilation a necessity?

sas

gizmo555 wrote: »

I don't really understand this.

There's a good reason for that. It's nonsense.

CJhaughey

mrgaa1 wrote: »

you should always re-air your house by opening windows for a period of time to allow fresh air - regardless of HRV's etc... The BER cert allows for cross-ventilation and certainly its a necessity.

Why is it a necessity?
If your system is setup for 2.5 changes per hour why would you need to open windows?

MicktheMan

CJhaughey wrote: »

Why is it a necessity?
If your system is setup for 2.5 changes per hour why would you need to open windows?

CJ, this seems a tad high! Mine's designed for 0.5 changes/hr.

fclauson

So be honest with me (I am glad we are developing this debate) does the air delivered by the vent system really

• sound
• taste,
• feel,
• smell

just like that open window air

That is my point - do i really want a Passive house - super efficient - but soleless

sydthebeat

fclauson wrote: »

So be honest with me (I am glad we are developing this debate) does the air delivered by the vent system really

• sound
• taste,
• feel,
• smell

just like that open window air

That is my point - do i really want a Passive house - super efficient - but soleless

the air "delivered" by the vent comes from the outside....

guess what, the air delivered from an open window comes from... yes, you guessed it... the outside.

fclauson... it sounds like you are trying to find every reason, however dubious, not to install one of these systems.... that is entirely your prerogative.

fclauson

fclauson wrote: »

So be honest with me (I am glad we are developing this debate) does the air delivered by the vent system really

• sound
• taste,
• feel,
• smell

just like that open window air

That is my point - do i really want a Passive house - super efficient - but soleless

If you consider the concept of fresh air to be a cool undulating draught then it's unlikely that a MHRV system will replicate that, unless you have an oscillating fan in the room as well.

The feel is cold air!
The sound is noise outside an open window!
The taste & smell are the same... (as the inlet vent).

My missus has the same difficulties grasping this as well!! :rolleyes: as well as :mad:

As for the soleless I walk barefoot around the house no problem!
You need to define soul when it comes to what you actually want, An efficient house or one that has the old world charms along with the draughts and extra fuel costs.

CJhaughey

MicktheMan wrote: »

CJ, this seems a tad high! Mine's designed for 0.5 changes/hr.

It is at the moment because of the heat from the last few days, I have large 3-glazed windows to the SW 12m2 of them and if I don't shade and run a higher airflow the house can overheat.
There is a max switch on the Temovex that you can flick and get big flow, in the winter I cut it back but not quite to 0.5 p/h.
OP I have friend who has an air to water heat pump that runs from the house air, his wife always throws the windows open every morning(force of habit from living in old damp houses) and this makes his efficiency very poor, If you or your wife have this habit and find it hard to change then I suggest you rethink speccing HRV.
It is not to everyones taste.

fclauson

sydthebeat wrote: »

the air "delivered" by the vent comes from the outside....

guess what, the air delivered from an open window comes from... yes, you guessed it... the outside.

fclauson... it sounds like you are trying to find every reason, however dubious, not to install one of these systems.... that is entirely your prerogative.

Sydthebeat - not at all - went to the selfbuild show last week end and had it rammed down my throat that a heat recovery system was the only way to go and that saving energy was the only direction which makes sense and that carbon emmissions are the sporn of the devil

Hence the debate - and keep it comming - do these systems really deliver "fresh" air

I wanted some real life feedback of these sytems - having worked in air condition offices for some 20 years in the UK / Irish weather - I still beleive these systems fail to deliver "fresh" air - the metal/plastic duct changes the ion make up of the air and part of what makes air fresh is the smells it brings with it.

So given all that - it seems I will probably install one of these systems - but make sure that a back up heat source is available to re-heat the house when needed

One of the options I have seen for this is given a large solar array provides more h/w than needed that you can use the excess heat from this to warm the incomming air thought he HRVS

Francis

gizmo555

fclauson wrote: »

One of the options I have seen for this is given a large solar array provides more h/w than needed that you can use the excess heat from this to warm the incomming air thought he HRVS

Hmmm . . . I recently installed HRV and spoke to a number of prospective suppliers before choosing my system. One of them enthusiastically touted this as an optional extra to their system. The people I eventually went with frankly and honestly told me that they had installed this setup in a couple of houses but no longer offered it as an option, because in their experience it didn't work.

The problem is that the times you need space heating for the house are the times when the solar panels are providing the least input, and the times when the panels are providing excess hot water are those when you wouldn't want heating on anyway.

sinnerboy

fclauson wrote: »

So given all that - it seems I will probably install one of these systems - but make sure that

1. your ceiling outlets are dampered . Intumescent collars do not work
2. that the fan motor is linked to the fire alarm to power down in the event of fire
3. that you get a remote monitoring panel to be located somewhere you will see it every day ( utility ) to warn you if intended velocities are not being reached and if the filters need changing
4. you locate the fan unit in a place that makes it easy to change / clean the filters

sas

sinnerboy wrote: »

4. you locate the fan unit in a place that makes it easy to change / clean the filters

This follows onto something else I was told recently. Locate the HRV unit inside the thermal envelope. If you put it in a cold attic (as appears to be common practise) you take a hit on it's performance.

sinnerboy

Good one sas - makes sense . You tend to see the units located in Irish attics wrapped in foil faced quilt insulation . So how do you maintain that ( the insulation ) intact if you need to attend to filters regularly ?

Really anyone looking at a new build or major refurb must see their Utility as a fairly large room ( 3m x 4m min ) for which only half the space is really a Utility in "the housewife" sense . The other half at least is really a plant room . The boiler or heat pump , hot water cylinder , ( and if applicable buffer tank ) , HRV unit , pumps , UFH manifolds ( if applicable ) , solar panel control unit , and perhaps even the cold water tank should be within the thermal envelope to maximise fuel efficiency .

Anyone planning a dormer bungalow beware - stuffing this stuff into the small attic crawl spaces is not ideal to say the least .

gizmo555

sinnerboy wrote: »

Good one sas - makes sense . You tend to see the units located in Irish attics wrapped in foil faced quilt insulation . So how do you maintain that ( the insulation ) intact if you need to attend to filters regularly ?

My one's in the attic. The unit is enclosed in a rigid polypropelene casing which is insulated on the inside. The unit itself is suspended on light chains from the roof trusses. The reason for suspending it like this is to reduce vibration and noise and to allow insulation to be laid underneath it.

gizmo555

gizmo555 wrote: »

My one's in the attic. The unit is enclosed in a rigid polypropelene casing which is insulated on the inside. The unit itself is suspended on light chains from the roof trusses. The reason for suspending it like this is to reduce vibration and noise and to allow insulation to be laid underneath it.

Mine's exactly the same, but if doing it again I'd do as sinnerboy is suggesting.

The "plant room" would be soundproofed anyway.

gizmo555

Deleted User wrote: »

Mine's exactly the same, but if doing it again I'd do as sinnerboy is suggesting.

The "plant room" would be soundproofed anyway.

I'm by no means an expert and I'm not advocating one approach over another. I will say, however, that it seems to me that another advantage of attic location which hasn't been mentioned so far is simpler ducting. In particular, all the ducts from the upstairs rooms go straight into the attic space, giving the shortest possible path with fewest bends back to the unit. These shorter runs must at least to some extent offset possible heat losses from the unit itself.

Also, my installation was a retrofit in a dormer bungalow, and I find it difficult to envisage how it would have been even possible to easily get all the required ducting back to my ground floor utility room.

CJhaughey

sinnerboy wrote: »

G
Really anyone looking at a new build or major refurb must see their Utility as a fairly large room ( 3m x 4m min ) for which only half the space is really a Utility in "the housewife" sense . The other half at least is really a plant room . The boiler or heat pump , hot water cylinder , ( and if applicable buffer tank ) , HRV unit , pumps , UFH manifolds ( if applicable ) , solar panel control unit , and perhaps even the cold water tank should be within the thermal envelope to maximise fuel efficiency .

Thats exactly how mine is, DHW tank 400l washing machine right next to it, above the tank is the pump for the Solar collectors and above the washiong machine is the solar panel controller.
on the other side of the tank is the HRV unit and pipework/pressure vessels for the DHW.

sinnerboy

gizmo555 wrote: »

I'm by no means an expert and I'm not advocating one approach over another. I will say, however, that it seems to me that another advantage of attic location which hasn't been mentioned so far is simpler ducting. In particular, all the ducts from the upstairs rooms go straight into the attic space, giving the shortest possible path with fewest bends back to the unit. These shorter runs must at least to some extent offset possible heat losses from the unit itself.

Also, my installation was a retrofit in a dormer bungalow, and I find it difficult to envisage how it would have been even possible to easily get all the required ducting back to my ground floor utility room.

Not trying to be "clever" gizmo ( chorus of "don't waste your time SB" ) or criticising of anyone . What you've described is more than reasonable for your situation imo.

sas

While we're here...

I have also been told that the best position for the HRV unit is rather awkwardly at the centre of the house, as close to an external wall as possible!

You want your internal pipe runs to the rooms to be as short as possible. You also want the inlet and outlet pipes between the unit and the external wall as short as possible ( less than 1 metre for these apparently )

If you're house is retangular you want the plant room on an external in the middle of the longest elevation. It represents the best compromise.

Having said that, the actual effect on efficiency could be minimal. When the PHI says that it will have an impact on the efficiency they can be talking about 1% of 1%.

I've seen the pipe layouts designed for a certified passive house by one of the better HRV companies and they have the unit in the middle of the shortest elevation. The pipes themselves were also placed to allow for ease of installation and use of the attic space more efficiently. The attic was inside the envelope incidently.

MicktheMan

sinnerboy wrote: »

You tend to see the units located in Irish attics wrapped in foil faced quilt insulation . So how do you maintain that ( the insulation ) intact if you need to attend to filters regularly ?

Having just cleaned my hrv filters, which is located in the attic, it occured to me that as I get on in age, this activity will become a right pain (literally).
This is, imo, a very important point because if these filters are not maintained very regularly then the air your breath will be affected.
Also something to keep in mind perhaps when deciding on hrv unit location.
Btw, I clean my filters when I get my esb bills - every 2 months.