# Chimney in airtight passive house



## LouisCribben (30 Nov 2009)

Am I correct in thinking that for a house to reach the passive house standard, a chimney is not possible ?

Obviously an open sitting room fire is out of the question, because it makes air tightness impossible, but what about a solid fuel unit ?

I'm thinking that no matter how a chimney is constructed, it always creates a thermal bridge to the outside. Am I correct.


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## olddog (30 Nov 2009)

A sealed stove with an external air supply intake should be OK


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## sydthebeat (30 Nov 2009)

Practically speaking, yes, there should be no chimney in a passive house.

Not only is the air tightness a factor, notwithstanding a room sealed stove, but more importantly the thermal bridging of the chimney could mean that passive levels couldnt be met.


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## LouisCribben (30 Nov 2009)

I guess it also rules out a wood pellet burner for the same reason........


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## galwaytt (3 Dec 2009)

Louis
Whilst that may be correct to the letter of the standard, it's you who's living in the house, not the Institute..........a room-sealed unit, with a good flue detail, will have little practically-meaurable difference in the performance of the house - from an economics point of view.

You can have passive performance levels, and still not get a PHI cert, so don't go beating yourself up over this.

Look at it this way - if you open a window for fresh air, it'll make a bigger difference...........

...don't sacrifice everything YOU want, to the whims of a 'body' , somewhere else, for a piece of paper.

Put in the stove.


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## sydthebeat (3 Dec 2009)

thats a fair point GTT, but lets not kid ourselves that a "passive" house is one that is not certified.

There most certainly is a point at which "passive" houses become expensive to build due to teh bells and whistles approach to solving energy usage issues, but to truely have a passive house you must have it certifed. this certification includes a data logging timeframe afterwards to prove its credentials. 

Otherwise its entitled a low energy build... which is noble in itself.


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## sas (3 Dec 2009)

It is perfectly possible to have a chimney in a passive house.

This one as it says is being built in conjunction with the PHI.
[broken link removed]

It has 2 chimneys. 1 inside the body, 1 outside.

Both were built using traditional masonry.

The internal one was built with an adapted detail using insulating blocks where it bridges the airtightness\insulation layer in the roof.

The flue also contains 2 valves even though a room sealed is specified. There is no such thing as a truly airtight stove apparently. 1 of the valves is on the air source pipe for the stove, the 2nd in the chimney itself close to the insulation layer.

This chimney is so well designed that it is not considered a cold bridge in the PHPP. 

It is easier to detail the chimney (thermally) if it is outside the body of the house. This can introduce structural issues depending on your build method.

If the company that did your PHPP knows what they are doing they should be able to provide a detail.

Very best of luck to you.


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## LouisCribben (6 Dec 2009)

Thanks SAS, good answer.
I'm trying to get my head around how the valves work in the flue. 
Obviously the valves open when the fire is on, and close when there is no fire on

Are the valves automatic, or do they need opening manually when a fire is lit, and closed manually when there is no fire.  It might sound like a stupid question.


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## sas (6 Dec 2009)

LouisCribben said:


> Thanks SAS, good answer.
> I'm trying to get my head around how the valves work in the flue.
> Obviously the valves open when the fire is on, and close when there is no fire on
> 
> Are the valves automatic, or do they need opening manually when a fire is lit, and closed manually when there is no fire. It might sound like a stupid question.


 
I'm 99% in that house the pair are going to be wired to a single switch which will be controlled by the occupant as you suggested.


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## galwaytt (9 Dec 2009)

sydthebeat said:


> thats a fair point GTT, but lets not kid ourselves that a "passive" house is one that is not certified.


 
....let us not kid ourselves that a house without a PHI cert isn't passive, either.




sydthebeat said:


> ....but to truely have a passive house you must have it certifed. this certification includes a data logging timeframe afterwards to prove its credentials.
> 
> Otherwise its entitled a low energy build... which is noble in itself.


 
I'm afraid I disagree. You truly have a passive house when it performs like one. The presence or absence of a cert will not affect that performance one iota. 

Remember: PHI is a commercial organisation, who charge for the service. That your house could meet all the requirements, but that you elect not pay for a PHI cert, does not disqualify you from having a passive house.


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## sydthebeat (9 Dec 2009)

galwaytt said:


> I'm afraid I disagree. You truly have a passive house when it performs like one.



I agree. But who checks that it is performing?



galwaytt said:


> The presence or absence of a cert will not affect that performance one iota.



again, i agree. But a certificate is proof non occupants that its DOES perform.
Without a cert, wheres the proof?


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## onq (9 Dec 2009)

sydthebeat said:


> <snip>But a certificate is proof non occupants that its DOES perform.
> Without a cert, wheres the proof?



Would the heating bills not provide some form of empirical proof.

[this, from a guy who issues certs for a living ]

ONQ.

PS Not passive house certs, BTW...


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## sas (9 Dec 2009)

I'm wading in here. I'm completely with Syd on this and I'm going certified (assuming I can satisfy the criteria).

You won't have heating bills. You will have an ESB bill alright. But most passive houses (even in our milder climate) will have a stove of some sort as a back up and it's not easy to prove how much or little you light it.

Plus there are people that are very warm souls that need a window open at night in order to sleep. There are those that prefer to be able to walk around in our underwear when there's a foot of snow outside. To the former, any house could be warm enough. You see where I'm going.

My biggest fear.... I'm building a house (3256 sq ft) to PHI spec with the target to achieve the certification. However, if I fall short (say 16kw instead of the 15kw target) I don't get the cert but the house will perform like a passive house. The certification has to draw the line somewhere so I don't have an issue with this. If faith should deal us a bad hand 5 years down the line and we were forced to sell, all I really have is a big house that needs a heating system installed from a buyers perspective. I'm actually planning on burying rad pipes in the screed so that should that happen (or if we fall we short of passive) I have a fall back that doesn't involve digging up floors etc to resolve.


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## sydthebeat (9 Dec 2009)

onq said:


> Would the heating bills not provide some form of empirical proof.
> 
> [this, from a guy who issues certs for a living ]
> 
> ...



nope 

without delving into the murky debate of what is actually 'passive' and what is not...
the consensus is passive houses do not consume more than 15 kwhr/m2 of heating and cooling energy per annum. Your heating bills will not reflect this. If someone has wood fuel for free but needs to burn 30 kgs a day for comfort does that mean its a passive house? 

see here for a synopsis
[broken link removed]

_Here are the five points that define the current German Passivhaus Standard for Central European Countries:
− Heating criterion: The useful energy demand for space heating does not exceed 15 kWh per m² net habitable floor area per annum.
− Primary energy criterion: The primary energy demand for all energy services, including heating, domestic hot water, auxiliary and household electricity, does not exceed 120 kWh per m² net habitable floor area per annum.
− Air tightness: The building envelope must have a pressurization test result according to EN 13829 of no more than 0.6 h-1.
− Comfort criterion room temperature winter: The operative room temperatures can be kept above 20 °C in winter, using the abovementioned amount of energy.
− All energy demand values are calculated according to the Passive House Planning Package (PHPP) and refer to the net habitable floor area, i.e. the sum of the net floor areas of all habitable rooms._

from: [broken link removed]


once these parameters are met then that house can be said to be 'passive'... if they are not met then the dwelling is simply low energy. The passive house parameters are a method of describing a standard to be met, thats all.


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## olddog (9 Dec 2009)

So, 

If OP would like a chimney then no reason not to have one

unless OP is concerned as to

how many angles can dance on the top of a pin head


Regards

Olddog

( stay real, stay warm )


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## Horatio (10 Dec 2009)

Noob question: How is heat escaping when people enter & exit these passive houses handled?


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## LouisCribben (10 Dec 2009)

Horatio said:


> Noob question: How is heat escaping when people enter & exit these passive houses handled?


 
its not handled

when the triple glazed argon filled airtight doors are opened, heat will escape.


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## LouisCribben (10 Dec 2009)

sas said:


> I'm wading in here. I'm completely with Syd on this and I'm going certified (assuming I can satisfy the criteria).
> 
> You won't have heating bills. You will have an ESB bill alright. But most passive houses (even in our milder climate) will have a stove of some sort as a back up and it's not easy to prove how much or little you light it.
> 
> ...


 
You are concerned that the house you are building to passive standard may fall short of the standard, i.e. it might use 16kwh/m3 to heat.
Just a question really, shouldn't you know before you start building if the house is going to pass, assuming the Passive House software has been used, and the house is built with good workmanship with all the correct materials.
What can go wrong ? I'd be thinking dont bother putting in pipes under the screed, just get your design and build right !

I'm a bit unclear too about the data logging to prove its passive. Obviously they need to see your electricity bills during the monitoring period......its impossible to tell from an electricity bill what energy was used for heating alone (unless they put a kw/h meter on all heating devices). 
Also it would be difficult to monitor how many kw/h came from coal or wood, should the house have a solid fuel unit (not difficult mathematically to work out) but difficult for the passive house people to verify how much wood was burned.


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## gooner (10 Dec 2009)

I was in a house that was being monitored and the heat recovery unit was switched off,which is bound to have an effect on the reuslts.I was told that they switched it of just before I arrived,that they had been showing another person around and must have forgot to switch it back on.Maybe genuine,but I know another guy who was there on another day and had the exact same story!!


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## sydthebeat (10 Dec 2009)

LouisCribben said:


> its not handled
> 
> when the triple glazed argon filled airtight doors are opened, heat will escape.



Ever heard of draught lobbies??

its completely obvious that the use of the house after will affect the actual performance of the project. Whether or not a build is "passive" means it meets set parameters. These parameters HAVE TO make certain usage assumptions ie a living area constant temp of 20 deg etc. 

Doors are opened when someone walks through them. This quick temporary action is not going to cause a significant temperature drop throughout the dwelling so as to make the passive heating system useless. 

I have heard the same queries about windows "sure, what happens if you open a window".... again the same is applicable. Firstly you need to ask why windows are opened??? in summer it is usually to counteract over heating. This in effect is passive cooling. So when else would you open a window??? to let out smells and water vapour. Both of these issues are dealt with by means of mechanical ventilation with an intelligent control system. there will be facility for rapid exhaust of air from rooms with steam or smells....

so when else would you open a window for a length of time that would affect internal temperatures????

A sense of reality needs to be maintained ... !!


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## galwaytt (10 Dec 2009)

sydthebeat said:


> I again, i agree..... But a certificate is proof non occupants that its DOES perform.
> Without a cert, wheres the proof?


It's only 'proof', if it passes. What if it fails, even by a tiny amount ? Does that make it a non-passive house, performance-wise ? No it doesn't...



onq said:


> Would the heating bills not provide some form of empirical proof.
> 
> [this, from a guy who issues certs for a living ]
> 
> ...


 
+1, proof of the pudding is the eating, and all that... 



sas said:


> I'm wading in here. I'm completely with Syd on this and I'm going certified (assuming I can satisfy the criteria).
> 
> You won't have heating bills. You will have an ESB bill alright. But most passive houses (even in our milder climate) will have a stove of some sort as a back up and it's not easy to prove how much or little you light it.
> 
> ...


 
That is exactly my point.......

But you will have heating bills - but in a different format.  No oil, or gas, but the heating effect of living in the house, and the electrical consumption, is a defacto bill.

But I see where you're coming from, but you're actually making the same point as I: you are building towards an aspirational performance level, and if you just happen to miss it, it's still a very good house, no PHI cert, but you'll have a back-up plan. This is all good, but also infers a certain disfunction between the cert, the real world, and of course, that huge variable: personal preference.

And of course, you're house could technically meet all the requirements from a quality-of-construction point of view, and still fail, if, for instance, the design, or location, or orientation of the house works against you.  And these are, frankly, insurmountable obstacles, compared to construction details.

For example, I know someone (in the trade) with a beautiful house. He will be the first to say it is pointless he doing a BER on his own house, and especially an airtightness test as he, from one end of the year to the other, NEVER closes the sashes on the upstairs windows ! So, does that make his house 'bad' ? No, it just makes his, fit his personal preference, which is what a HOME - as distinct from a house - is supposed to do.



olddog said:


> If OP would like a chimney then no reason not to have one


 
I think the OP needs to answer this first, actually, and then decide what's possible, performance-wise (whether passive, 'Passiv', 'high performance'...or whatever......



Horatio said:


> Noob question: How is heat escaping when people enter & exit these passive houses handled?


 
Ha, good one ! - airlock, anyone 



LouisCribben said:


> its not handled
> when the triple glazed argon filled airtight doors are opened, heat will escape.


....indeed it is ! Even 'Passiv' people have to go out, sometime.

Unless they're bears, that is.......and hibernate 'til spring 



LouisCribben said:


> You are concerned that the house you are building to passive standard may fall short of the standard, i.e. it might use 16kwh/m3 to heat.
> Just a question really, shouldn't you know before you start building if the house is going to pass, assuming the Passive House software has been used, and the house is built with good workmanship with all the correct materials.
> What can go wrong ? I'd be thinking dont bother putting in pipes under the screed, just get your design and build right !
> 
> ...


 
....aah, now we're getting somewhere. This is a good point. Consider the corollary of all you consider, above, and you are purchasing said house in 5 years time: what's to say the PHI cert is in any way indicative of a real-life living situation ? The only true arbiter is.......money. How much it cost to provide the heat - in whatever form - it took to live in.



gooner said:


> I was in a house that was being monitored and the heat recovery unit was switched off,which is bound to have an effect on the reuslts.I was told that they switched it of just before I arrived,that they had been showing another person around and must have forgot to switch it back on.Maybe genuine,but I know another guy who was there on another day and had the exact same story!!


 Exactly. And, just as sure as the likes of BER's not including habitable space, wait 'til you see 'creative' designers 'adjusting' floor sizes and room volumes to achieve the desired results...........


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## sydthebeat (10 Dec 2009)

GTT,

i agree with a lot of what you are saying...

the ONLY thing i disagree with is your use of the title of "passive" on dwellings which do not meet the standard.

call them low energy, call them future homes, whatever you want... its only when you give them a title that, by definition, means they need to meet set standards, that i have an issue with....

you cannot call a skoda a volkswagon just because it has a VW engine....
titles depend on standards met....


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## LouisCribben (10 Dec 2009)

Yeah it's true, you can't call a house a passive house unless it has the cert.

Without a cert, it hasn't been formally measured and tested against the objective set of criteria required for a passive house. 
You cant be sure it would meet the criteria unless it formally passes the test.

Of course a house without a cert may meet or even exceed the passive house standard, but to call it a passive house, you need the proof...


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## sas (10 Dec 2009)

LouisCribben said:


> You are concerned that the house you are building to passive standard may fall short of the standard, i.e. it might use 16kwh/m3 to heat.
> Just a question really, shouldn't you know before you start building if the house is going to pass, assuming the Passive House software has been used, and the house is built with good workmanship with all the correct materials.
> What can go wrong ? I'd be thinking dont bother putting in pipes under the screed, just get your design and build right !


 
In theory, if you are an experienced passive house designer, you can have every detail worked out based on past experience and the initial PHPP will match the end result.

However, we have no very experienced passive house designers in Ireland. There are only 5 certified homes that I am aware of although a 6th seems to be in the offing based on "About the house" this week.

I believe it is naive to assume that you will foresee every problem and get the construction details implemented perfectly. Achieving the required level of airtightness is an outstanding achievement. 

To put this in context, I am aware that 1 of the 5 certified houses didn't achieve the required airtightness level. I won't be saying which one it is. I've heard stories of masking tape being used during the blower door test to seal windows which were performing poorly despite being supplied by a highly regarded PH window manufacturer.

Another one of them only did 1 airtightness test using the front door. This elimated the effect of what was a poorly performing door on the air tightness result. I believe the correct approach is to test twice using 2 different doors\openings and you take an average of the 2.

I've seen another 1 in the flesh. I believe that they decided to lie about certain details in order to achieve the standard. I have no proof of this but there are several things about the construction that are massive cold bridges. I know for a fact that after the certification was obtained an addition was made to the house in terms of a back up heating system.

Something I am personally concerned about on my build. The best detail for mounting windows in an externally insulated masonry house involves mounting the windows in front of the block work supported on brackets. The window manufacturers will provide recommendations on the sizing and number of these brackets. Your engineer may have another more conservative view. The PHI will likely declare both as completely overkill and massive cold bridges. This can very quickly throw certification out the window when the brackets are factored into the PHPP.

Different build systems present different issues.


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## LouisCribben (10 Dec 2009)

You've highlighted a real problem, the expertise in building energy efficient houses in Ireland is not good, from designers to builders to tradesmen

You're asking them to raise their game a lot to create a passive house, it requires vastly more thought and attention to detail than they are used to.

It's disappointing if what you heard is true i.e. some passive houses are achieving certification when they don't deserve to.
I'm sure the institute would sack any assessor who they knew were not doing their job correctly though.


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## Buildright (28 Dec 2009)

In Fairness you can understand why they went easy on the first houses, It did after all assist in promoting the concept. Experience is starting to show that you should really design for 12kWh's as verification can highlight deficiencies that were not evident at design stage and you need some wiggle room. The most important inputs in PHPP are Treated floor area and weather files. Treated floor area excludes stairs, walls and voids and means that the net area used in the calculations is less than the net floor area that you used for construction costing, the heat demand must also be lower. Your 240sq.m house measured inside the outer walls will have only say 180sq.m of heated area, once you subtract non usable space, therefore you need a 25% lower heat demand for the lower 'treated floor area' space. A Passive house in the midlands uses weather data for Birr, this adds a 10- 15% higher insulation spec than a house designed with Dublin Weather data, so its well worth getting a site specific weather file. Meteonorm in Switzerland is the standard for this.

I think a 'Passive House' at 20kWh's with 10-12 watt per metre square peak heat load is passive, but it cannot rely on the ventilation system to deliver comfort alone. The 'Passivhaus standard' is certainly worth persueing. Whats missing here is the involvement of a statutory agency on the model of Minergie in Switzerland or the excellend AECB in the UK to provide guidance and implementation. SEI have ticked a box called inform, that simply isn't suffucient. We missed a golden opportunity to become passivhaus leaders in the Anglo-American World as distinct from the Continental European market. England Scotland and Wales now have the structure in place to roll out passivehouse but are short on experience. We have made all the mistakes and now, collectivly have the experienc but unfortunatly no Structure. The same can be said for BREEAM and CODE, holistic environmental assessment tools, despite the good work done by the Greens, we're eon's behind the UK in developing expertise in sustainibility for the built environment.


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## galwaytt (4 Jan 2010)

sas said:


> Something I am personally concerned about on my build. The best detail for mounting windows in an externally insulated masonry house involves mounting the windows in front of the block work supported on brackets. The window manufacturers will provide recommendations on the sizing and number of these brackets. Your engineer may have another more conservative view. The PHI will likely declare both as completely overkill and massive cold bridges. This can very quickly throw certification out the window when the brackets are factored into the PHPP.
> 
> Different build systems present different issues.


 
Lot's of good points there, but the latter is one of the most often-encountered.  That is, the interface between the fabric/structure, and the requirement for for other, non-thermal, criteria to be met.

Consider: irrespective of the ability, or desire, to achieve a  PHI (or any other) cert, and on the issue of bridging, if a *structural* requirement exists for a (column/beam/bracket/lintel/whatever) , then that is the paramount issue, and the bridging simply has to take 2nd place.  Otherwise the structural eng simply won't sign off the building.  There is no-one who will sign off a building, structurally, with a compromise in it, as it is 'mission-critical' as they say, and I dare say there's no-one who would want them to, either...........

Window and door systems are a case in point.  We are working on a "passive" house for someone, using a cement-board and render cladding, with a 50mm ventialated clear cavity.  But the window frames are 95mm deep.   So, the frame is obviously protruding into the 'frame', by an amount.   What then is the situation, there, even before brackets are considered?

Triple-glazing exacerabates the issue, due to weight.

Similarly door frames (and especially those on high performance systems i.e. very heavy ones) will require substantial fixing(s) to prevent subsequent movement through end-use.  (Slamming a 75kg door does knock the stuffing out of jambs and reveals.........).   

Inevitably, somewhere in a building, if this situation arises, the structural guy will always trump the thermal guy.......and unless the PHI guy is signing off the structural cert, or warranty-ing the windows, and any subsequent issues of finish cracks etc, and underwriting it, it's really moot what he thinks........


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## galwaytt (4 Jan 2010)

Buildright said:


> In Fairness you can understand why they went easy on the first houses, It did after all assist in promoting the concept.


 Maybe so, but fudging at the start sets a poor precedent, and you run the risk of bringing the whole thing into disrepute.



Buildright said:


> .......... The most important inputs in PHPP are Treated floor area and weather files. Treated floor area excludes stairs, walls and voids and means that the net area used in the calculations is less than the net floor area that you used for construction costing, the heat demand must also be lower. Your 240sq.m house measured inside the outer walls will have only say 180sq.m of heated area, once you subtract non usable space, therefore you need a 25% lower heat demand for the lower 'treated floor area' space.


 I may be alone in this, but I don't think that will work for people, 'on the ground' as it were. Practically, no-one will accept 'lower' standards of comfort (even if it's only perceived) in these typical areas, e.g. halls, corridors, landings etc. For one reason alone, in an even moderately open-plan design, it will promote 'draughts', or what people perceive to be draughts. And people will complain.
It should be simpler than that - all areas should be designed to the highest of any established required values, irrespective of end-use.



Buildright said:


> Whats missing here is the involvement of a statutory agency ..... SEI have ticked a box called inform, that simply isn't suffucient.


 I'm afraid the last thing we need is another quango. We are over-run with them, the vast majority simply being a waste of time.



Buildright said:


> We missed a golden opportunity to become passivhaus leaders in the Anglo-American World as distinct from the Continental European market....., despite the good work done by the Greens, we're eon's behind the UK in developing expertise in sustainibility for the built environment.


 
We probably have missed the boat, but contrary to your point, I'd point the finger AT the Green's for the failure - one reason we are so far behind is BECAUSE of their inaction, and the lack of either a level playing field, or, measurable support for innovation. When you consider that cavity block houses are still being built, despite the huge amount of data on the subject, or, when you consider that you can get no support to build a 'high perfromance' house in the first place, but you can build a 'conventional' one, and get 'support' a few years down the line, to 'upgrade' it, then you know the system is backwards.

I very specifically lost a job to build a house because the (client told me) that hecould get no grant for building to a higher performance, no grant for a windmill, PV panels, water-harvesting etc. Despite his remonstrations with SEI on the subject, and geting no succour, he just went ahead and built a std cavity-block house, which is (undeniably) cheaper. When I asked what was his long-term take on the house performance, he told me that quite simply, this being his first house, he would likely move in 10 years time, and that the performance down the road was not an issue, as it would be someone else's problem, then, and he saw no justification in spending anything over the minimum, in the interim, as he would never recoup it...........granted, this is is only one person, but extrapolate that across the country, and factor in the almost non-availability of finance from the banks (despite what they say), and you'll see there is more work required to deliver from the aspirational.......


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## onq (4 Jan 2010)

I absolutely agree with you Galwaytt.
This is something I should have seen for myself.
Jeff Colley in Construct Ireland has gone some way to find a means to fund home insulation improvements through utilities billing.
There is no comparable means of funding the extra over costs of building to Passive House standards, never mind to Carbon Neutral by 2013.

ONQ.


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## sydthebeat (4 Jan 2010)

onq said:


> There is no comparable means of funding the extra over costs of building to Passive House standards, never mind to Carbon Neutral by 2013.
> 
> ONQ.



lets be clear here however, proposed part l 2012 standards will be very very stringent and while not "passive" will be damn close.

i honestly cannot see how our construction trades persons will be educated as to how to achieve these standards based on previous experience. Believe it or not, theres still many architects / engineers / contractors who have trouble understanding 2002 regs... never mind the huge seachange that was 2008....


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## onq (4 Jan 2010)

sydthebeat said:


> lets be clear here however, proposed part l 2012 standards will be very very stringent and while not "passive" will be damn close.
> 
> i honestly cannot see how our construction trades persons will be educated as to how to achieve these standards based on previous experience. Believe it or not, theres still many architects / engineers / contractors who have trouble understanding 2002 regs... never mind the huge seachange that was 2008....



Syd, I'm with you there.

I've seen evidence that builders don't even follow the details set out by the timber frame suppliers - even though some of them are in, they're not properly installed or parts of the detail are missing.

The real problem is the lack of oversight that came in with self-certification.

How many people do you know who actcually know enough about detailing to certify everything?

I know a fair amount about the 1997 and 2002 regulations, but I'm not sure I understand all there is to know about the recent regulations.

The reason being that in relation to the previous regulations there were things I only addressed as I came upon them and asked myself the question, "does this comply?"

In al case such as recessed downlighters the standard detail - used all over the country I have no doubt - was apprently breach of Part B's requirements for a 1st floor/Gd floor ceiling of FR 30.

Lo and behold! Fire hoods had been on sale for years to deal with the problem, but how many people installe them in timber floor construction?

Not a lot in my personal [as opposed to professional] experience.

ONQ.


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## sydthebeat (4 Jan 2010)

i agree onq

also, i think the culture of the "6 site visits for certification" which exists outside the pale is totally inadequate to certify current building standards. It may have been ok for post 97 houses, but now that everything from rising walls to downlighters to boiler pipework to letterplates is regulated, its simply impossible to certify with as little as six visits (or less in some cases)

the problem is joe public doesn't care. He just wants to pay the lowest fee for what he sees as an inconvenience. And as long as there are guys out there, and financial institutions / solicitors who accept these practises, it will continue, regardless of how complex the regs are!!


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## Buildright (4 Jan 2010)

Originally Posted by *Buildright* http://www.askaboutmoney.com/showthread.php?p=980292#post980292 
_.......... The most important inputs in PHPP are Treated floor area and weather files. Treated floor area excludes stairs, walls and voids and means that the net area used in the calculations is less than the net floor area that you used for construction costing, the heat demand must also be lower. Your 240sq.m house measured inside the outer walls will have only say 180sq.m of heated area, once you subtract non usable space, therefore you need a 25% lower heat demand for the lower 'treated floor area' space."

_


galwaytt said:


> I may be alone in this, but I don't think that will work for people, 'on the ground' as it were. Practically, no-one will accept 'lower' standards of comfort (even if it's only perceived) in these typical areas, e.g. halls, corridors, landings etc. For one reason alone, in an even moderately open-plan design, it will promote 'draughts', or what people perceive to be draughts. And people will complain.
> It should be simpler than that - all areas should be designed to the highest of any established required values, irrespective of end-use.
> 
> .....




I didn't explain that one clearly enough, All floor areas need to be heated or cooled to 20 degrees,and the surface area of element and the volume inputs take care of this. This is why the surface area to volume ratios are critical otherwise called compact design. Now only 75-85% of the floor area contributes heat gains. Therefore the 15-25% of unusable area contributes no heat gains, thus the thermal performance of the usable space has to be 15-25% better than if walls and stairs and crawl spaces were included. So its a higher performance,than you'd expect. Corridors and landings are usable spaces and heights less than 2m are put in as half floor areas. Drafts arn't a problem in passive houses, its fairly stable temperature with some stratification, the ventilation system evens this out, drafts are only perceived if diffusers are wrongly balanced or located.


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## Buildright (5 Jan 2010)

have a look at the following report

http://pass-net.net/downloads/pdf/report_international_ph-database.pdf

Ireland has 5 certified passive houses, but 25 houses that fall into the Passive category of 'very low energy house' of <20kWh/sq.m and aspiring to 0.6 ach per hour. I see nothing wrong with designing to this standard if the building is not designed to be a passivhaus prior to planning.

The greens are doing the right thing focusing funding on the retrofit markets. I don't want to be paying tax to subsidise a marble worktop in somone's one off McMansion 5 miles from town. Passivhaus new build dosen't need subsidies it needs expertise. The extra spend in passivhaus can be recovered in running costs over less than twenty years. The added benifits of fabric longevity due to reduced humidity and condensation and the incrreased comfort and ventilation are less quantifiable benifits. While converting an existing planning permission to passive can be difficult. Designing a house to be passive can make it easier. The risk in building standard spec is that it will will not be marketable in the future, even now the overhang of post celtic tiger units 125,000 or so, means that much of our current stock is worthless and there will not be much demand in the next decade for this stock as the economy contracts further. Designing a house that is still relevent in 2020 0r 2030 is the best option for your investment. Retrofitting a house to a sensible standard is incredably invasive. Far easier to do it now. Sure you can have it plumbed and wired to retrofit Eco-bling later when it becomes cheaper or subsidised, however as renewables track oil price, now could be as good a time as any. I would suggest insulating as far as possible, selecting the best possible window frame and designing out cold bridges and superflous details. Fit a cheap boiler and five to ten years down the line add the carbon neutral technology.


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## sas (5 Jan 2010)

Buildright said:


> I don't want to be paying tax to subsidise a marble worktop in somone's one off McMansion 5 miles from town.


 
My ears are burning....

I could point out that the alternative is subsidising someone who decided that a marble worktop was more important than insulation 5 years and now that things are tight want someone else to pay for their insulation\energy upgrades.

I have pretty big issue with the entire grant system. There has been plenty of money in this country for cars and foreign holidays etc. over the last 10 year. Those same people now want a hand out....

I personally like the PAYS system being championed by ConstructIreland.

Any grant system should heavily biased towards the most vulnerable. I don't see why the likes of me should be given a grant to install solar panels when the elderly couple down the road are freezing because they don't have the money to cover the excess over the grant.

How did we get from chimneys in passive houses to here????


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## LouisCribben (11 Jan 2010)

sas said:


> How did we get from chimneys in passive houses to here????


 
Because Threads usually go off thread after 3 or 4 posts ! 

After researching a bit more, I now understand that open fires are not necessary and are more effort than they are worth in a passive house...the heating requirement of 15kw/h per square can be met cheaply by electricity alone.

I can procure fossil fuels very cheaply, nonetheless, if I succeed in putting up a passive house, it wont make sense to use them.

In any case, I have come across a dvd of an open fire, might look ok if I can find a low watt lcd tv

[broken link removed]


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## feileacan (7 Sep 2010)

do i require a chimney in well insulated airtight timber house into wdhich i intend to put a solid fuel stove + BB?


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