Passive House - why bother?!

just do it

My understanding of the heat demand limit of 15kW/m2/yr to achieve passive house standards is to negate the need for a conventional heating system. Instead a heat exchange unit on the MHRV system can supply the necessary heat demand. Therefore the only heating requirement for the house orientates around the hot water tank with a coil running from this tank to the heat exchange unit. Simple system.

I've visited a number of passive houses and none have opted for this system instead opting for ufh. Indeed this is the safe bet in case a) the house fails to meet the passive house standard in the first instance, and b) the performance of the building diminishes over time resulting in a heat demand >15kW/m2/hr. But why bother with the exacting detail in the first instance if you're going to install a heat system that is overspec'd for the heat demand of the house? Is it not like training hard and winning the race but not taking the medal or prize money?!

1100010110

this should get interesting...

just do it

1100010110 wrote: »

this should get interesting...

That's what I hope;)

sinnerboy

I heard Tomas O' Leary ( owner of the the first Certified Passiv Haus ) that the Passiv Haus Institute themselves estimate that in the Teutonic countries that for every Certified Passiv House in existence there are about 10 non certified/passiv house inspired buildings.

So most passive houses we are likely to encounter will not be certified passiv houses which do undertake a high degree of ( must be paid for ) supervision not only of the design but also of the build process and it's testing before the PHI cert is issued. So one needs always to distinguish between a Certified Passive House and one which is not.

I would expect that just like in Germany / Austria and Switzerland that most house builders may be happy to seek out Passive House knowledge or methods "for free" and apply them as best they can to there own build.

And so without the required expert input to actually deliver to the PH standard I would counsel anyone that they are probably wise to put in at least a minimal heat distribution system .

Arguably a win / win i.e. if it turns out you don't need it afterwards , you have built a good house , but wasted money on the heating distribution system - and vice versa too.

Now the new Building Control Regulations which will compel house builders to hire what will be for the most part an RIAI Architect may influence this , we'll have to wait and see.

sydthebeat

just do it wrote: »

.... Indeed this is the safe bet in case a) the house fails to meet the passive house standard in the first instance, and b) the performance of the building diminishes over time resulting in a heat demand >15kW/m2/hr. !

a) in that case you would not be referring to a passive house

b) the passive standard defaults are very pessimistic. In all cases where the exact measurement is not known it defaults to the worst value. In doing so there is a built in "freeboard" in the certification system which will allow for diminishing returns over time. That being said, the most successful passive houses are the simple ones which have least chance of diminishing performance and are bases on non mechanical passive ideologies.

As current building regulations are damned near passive, i would argue that the passive standard is very achievable economically in the current climate.
In your example, consider that electrics is the most expensive 'per kwhr' fuel source so although the system set up might be cheap, the running costs may not be the most economical.

Certified

just do it wrote: »

I've visited a number of passive houses and none have opted for this system instead opting for ufh.

Yeah, I have found that to be the case also. What have they said in relation to it?
In my opinion, I think ufh is not very suited to the very changeable Irish weather, especially in a passive house as the house can overheat quiet often during the winter months when the sun decides to come out and the floor is heated.

I think the method of distributing the small amount of heat required via the mvhr system is a better option and it is practically doing it anyway. One significant issue for some however, is the lack of control.

Certified

just do it wrote: »

Therefore the only heating requirement for the house orientates around the hot water tank with a coil running from this tank to the heat exchange unit. Simple system.

Very true

belcampprisoner

you will need some heating in winter,you will have a comfertable house all year

about 21 degrees,you will not get drafts,you will not spend much on heating'

most passive houses come prefabricated from Germany Sweden etc so take less time to build

http://www.earthtechling.com/2013/04/how-passive-solar-paved-the-way-for-passive-house/

just do it

For clarity, I'm referring specifically to Certified Passive Houses with a heat demand within the range of 13.5 -14.5 kW/m2/yr. From what I've read the reason Wolfgang Feist selected 15kW as the cut off point was below this heat demand heating the incoming air sufficies to maintain a constant internal temperature of 20oC thus sparing the more expense of a conventional heating system. At this heat demand the cost of electricity is not so much a factor when compared to the capital cost of a more elaborate system. One can now look at only having to heat water in the cylinder by other means e.g. solar panes/ PV panels.

The original question still stands, why agonise over exacting detail to get the final reduction of 2-5kW/m2/yr to get below the passive house threshold if you're going to install a sytem well capable of supplying a heat demand well in excess of 15kW/m2/yr anyway? What is the economic sense in that? As it is a cost benefit analysis generally seems to show achieving a build with a heat demand ~18kW/m2/yr. A number of posters on here have also come to this conclusion over the last 3-4 years. So if you're going go to the extra expense of getting to certified passive level, surely you should pocket the saving on the conventional heating system it was designed to elimate?!

just do it

belcampprisoner wrote: »

you will need some heating in winter,you will have a comfertable house all year

about 21 degrees,you will not get drafts,you will not spend much on heating

Same could be said of a non-certified house designed along passive house principles in compliance with 2011 building regulations with a heat demand of 18kW/m2/yr. Such a house could be easily heated with the heating systems I've seen in the certified passive houses I've visited for a 28% increase in the annual heating bill. When your annual bill is in the €400-600 bracket that isn't a substantial extra burden. Take the certification fee alone of ~€1,500. The payback period on that using the saving on heating is 10yrs!

BryanF

just do it wrote: »

My understanding of the heat demand limit of 15kW/m2/yr to achieve passive house standards is to negate the need for a conventional heating system.

my understanding is

The term passive house (Passivhaus in German) refers to the rigorous, voluntary, Passivhaus standard for energy efficiency in a building, reducing its ecological footprint.[1] It results in ultra-low energy buildings that require little energy for space heating or cooling.[2][3]http://en.wikipedia.org/wiki/Passive_house

when the topic is discussed, we never hear much about the 'ecological footprint', mainly just in terms of € / YR heating.

what about a standard that looks for 'ultra-low energy building' in design, build and use?

my opinion on current regs,

1. since 2011 we have a reasonable part L building regulation standards though they still aren't prefect
2. nor is the associated DEAP software
3. and the proposed supervision of the building process definitely NOT
4. is there a policy of low Co2 / embodied energy in construction: no

passive house

1. is there lower co2 use in passive house during occupation: yes, its still higher standard than regs, and its more interested with limiting heat loss
2. is there good associated software: yes, certainly not as many flaws as DEAP, and is more indepth
3. is there a rigorous certification process: yes
4. is there a policy of low Co2 / embodied energy in construction: no

Instead a heat exchange unit on the MHRV system can supply the necessary heat demand. Therefore the only heating requirement for the house orientates around the hot water tank with a coil running from this tank to the heat exchange unit. Simple system.

I've visited a number of passive houses and none have opted for this system instead opting for ufh. Indeed this is the safe bet in case a) the house fails to meet the passive house standard in the first instance,

so what your saying is you dont spend the money on designer or building process?

and b) the performance of the building diminishes over time resulting in a heat demand >15kW/m2/hr.

if the air-tightness diminished by 50% is the fabric first and south facing solar gain approach not better than oversizing your solar system to meet the BER?

But why bother with the exacting detail in the first instance if you're going to install a heat system that is overspec'd for the heat demand of the house?

so what your saying is you dont spend the money on designer or dont trust the phpp software?

Is it not like training hard and winning the race but not taking the medal or prize money?!

you want a medal? i suppose that's a certificate to say its 'certified passive house'. the prize money is about how much it costs to run, not everyone is using a

payback period on that using the saving on heating is 10yrs!

id like to build a house and retire in it- at the rate I'm going that's a lot more than 10 year away

fclauson

just-do-it visited my house and we spoke about a lot of this

My feedback would be
going certified provided me with building control which is lacking here in Ireland - as one above says with the new regs will change - not sure - but I had a team of over 20 different trades and services all of who knew they would be shot by the main contractor if they messed up

On the UFH thing - I visited a passive house which had not UFH and they where retro fitting heated wall panels to provide the heat boost. I recently posted the following on the linked in forum - all figures are quoted in w/m2/day so size of property is removed from the equation.

Not certain why April needed 177% of PHPP heat demand - but I guess that's the variation of the weather for you.

You should note (I am just building the monitoring for this) that the build stayed within a band of 21 to 23 degrees through out this time (as measured at the MVHR) but the variation room to room was probably in the range of 19.5 -> 24 (south rooms being a bit warner than north - kitchen being cooler as the door has been left open in the "fabulous" summer weather this week)

to put this into PHPP speak
Jan PHPP gave 97w/m2/day and I used 35.10 (i.e. 36% of PHPP numbers) - average outside temps 5
Feb 28.41 vs 73.(i.e. 38%) - average temps 5
March 28.41 vs 38.82 (i.e. 73%) and March was coldest on record - average temp 4
April 11.41 vs 6 (i.e. 177%) - average temps 11

the monitoring system is currently giving
Incoming 6.69
Supply 21.75
Extract 21.56
Outgoing 9.69

MOTM

BryanF wrote: »

oversizing your solar system to meet the BER?

If you're referring to the renewables requirement checked by DEAP you should probably say "meet the TGD L requirement". You can't fail a BER even if you get a G rating on a new house. The pass/fail checks are only there because of TGD L, not because of BER. DEAP gives a warning if the solar fraction from the solar water heating system exceeds 60%.

MicktheMan

just do it wrote: »

From what I've read the reason Wolfgang Feist selected 15kW as the cut off point was below this heat demand heating the incoming air sufficies to maintain a constant internal temperature of 20oC thus sparing the more expense of a conventional heating system.

I don't think so.
My understanding from my training is that the heat demand of 15 kWh/m2/yr is an economical one (sweet spot) and not related to the ability of the hrv to heat the house. The ability of solely using the air (through the hrv system) depends on the heating load of the house as distinct from the heat demand. This is because air can only be heated to a certain temperature before the airbourne dust burns and you get an odour.

Btw, if the heating load is too high to allow air heating solely, you still do not necessarily need a wet distribution system!

sinnerboy

MicktheMan wrote: »

The ability of solely using the air (through the hrv system) depends on the heating load of the house as distinct from the heat demand. This is because air can only be heated to a certain temperature before the airbourne dust burns and you get an odour.

Agreed.

sinnerboy

just do it wrote: »

Same could be said of a non-certified house designed along passive house principles in compliance with 2011 building regulations with a heat demand of 18kW/m2/yr.

By what means do you verify this demand ? I mean assuming not going certified means you aim to "save" money by cutting out the expert oversight - how will you know you are achieving 18kW/m2/yr? . If you mean you have calculated by using DEAP or DEAP + PHPP and are then "going solo" with it then , again , I strongly advise you install a heat distribution system beacuse chances are you will not make the target.

just do it wrote: »

Such a house could be easily heated with the heating systems I've seen in the certified passive houses I've visited for a 28% increase in the annual heating bill. When your annual bill is in the €400-600 bracket that isn't a substantial extra burden. Take the certification fee alone of ~€1,500. The payback period on that using the saving on heating is 10yrs!

Again you seem to miss the point of certification. It is not a desk exercise alone. It involves a too series of on site verifications together with an oversite of your PH Designers calculations to deliver the target.
What you are doing above is nominally fixing a target and projecting from that.

Tone of voice is inevitably missing from text only communications such as this so I wish to say that you are provoking a good debate here and I am not meaning to "confront" you here

MicktheMan

just do it wrote: »

For clarity, I'm referring specifically to Certified Passive Houses with a heat demand within the range of 13.5 -14.5 kW/m2/yr.

just do it wrote: »

The original question still stands, why agonise over exacting detail to get the final reduction of 2-5kW/m2/yr to get below the passive house threshold if you're going to install a sytem well capable of supplying a heat demand well in excess of 15kW/m2/yr anyway? What is the economic sense in that?

I'm confused. Are we discussing the merits of going for certification versus not or the economic benefit of achieving the passive house standard? Imo, these are two separate discussions.

just do it wrote: »

As it is a cost benefit analysis generally seems to show achieving a build with a heat demand ~18kW/m2/yr. A number of posters on here have also come to this conclusion over the last 3-4 years. So if you're going go to the extra expense of getting to certified passive level, surely you should pocket the saving on the conventional heating system it was designed to elimate?!

In this case, is the theoretical project being supervised by a trained ph consultant or not? I ask this because without the continuous involvement of the ph consultant, how do you know that the house will actually perform at or close to the designed target?

just do it

sinnerboy wrote: »

Tone of voice is inevitably missing from text only communications such as this so I wish to say that you are provoking a good debate here and I am not meaning to "confront" you here

Yes you've got it, a good debate is the intention;)

Now I'll work through the replies.....

just do it

sinnerboy wrote: »

Now the new Building Control Regulations which will compel house builders to hire what will be for the most part an RIAI Architect may influence this , we'll have to wait and see.

Looking at new builds in my county there is no evidence of increased building control as of yet. 100mm cavity with insulated dryling is still the standard.

Given the above it does make sense to go for certified passive and all it entails below as it pushes the lead person, whether that be the builder, architect, engineer, project manager or self-builder to achieve a certain strict standard.

sinnerboy wrote: »

certified passiv houses which do undertake a high degree of ( must be paid for ) supervision not only of the design but also of the build process and it's testing before the PHI cert is issued.

just do it

sydthebeat wrote: »

b) the passive standard defaults are very pessimistic. In all cases where the exact measurement is not known it defaults to the worst value. In doing so there is a built in "freeboard" in the certification system which will allow for diminishing returns over time. That being said, the most successful passive houses are the simple ones which have least chance of diminishing performance and are bases on non mechanical passive ideologies.

Interesting to note the defaults are pessimistic in nature and borne out by FC's figures in a later post. Regarding simplicity, it also makes it easier and therefore cheaper to build.

sydthebeat wrote: »

As current building regulations are damned near passive, i would argue that the passive standard is very achievable economically in the current climate.

I've had a few scenarios run through PHPP on my design and a fully compliant design with current regulations is still quite a bit away e.g.

• 2008 part L compliant 49kWh/m2/yr
• 2011 part L compliant 36kWh/m2/yr
• A cost benefit option 7.7kWh/m2/yr (Windows U-value <1.1, 1.6 ACH, thermal bridges 0.04 psi Y)
• PassivHaus compliant 14.5kWh/m2/yr (window U-value <0.8, ACH <0.6)
• PassivHaus compliant 13.5kWh/m2/yr (thermal bridges reduced to 0.01 psi Y)

sydthebeat wrote: »

In your example, consider that electrics is the most expensive 'per kwhr' fuel source so although the system set up might be cheap, the running costs may not be the most economical.

Will have to look at the link. It's striking the balance between capital outlay and reduced ongoing running costs. One hidden advantage with a simplistic system based on electricity is less maintenance and need for repairs and unit replacement in 10-20 years time. I've a West coast location that favours an air to water heat pump but I'd have a serious concern with this as the sea air is severe on outdoor metal and mechanical items!

just do it

Certified wrote: »

Yeah, I have found that to be the case also. What have they said in relation to it?

One of the owners has replied below. The other was a regular poster on here as well and will no doubt add in his tupence worth if he stumbles upon the thread. He was possibly the second certified house in the country so wanted it as back-up. Cheaper to install at time of build rather than retrofititng.

Certified wrote: »

In my opinion, I think ufh is not very suited to the very changeable Irish weather, especially in a passive house as the house can overheat quiet often during the winter months when the sun decides to come out and the floor is heated.

I think FC would disagree with this.

Certified wrote: »

I think the method of distributing the small amount of heat required via the mvhr system is a better option and it is practically doing it anyway. One significant issue for some however, is the lack of control.

Have you been in many houses using this system solely? I haven't and would be interested to visit them. One thing I'll say for the houses I've visited (both certified and near passive) is they are very comfortable. There would be a view out there that MHRV systems lead to a stuffy internal environment. I've not experienced this nor has the owners of the houses I've visited.

sydthebeat

just do it wrote: »

I've had a few scenarios run through PHPP on my design and a fully compliant design with current regulations is still quite a bit away e.g.

• 2011 part L compliant 36kWh/m2/yr

using DEAP as the comparitive tool...

2008 Part L houses were generally in 150 - 125 kwhr/m2 brackets ie C3
2011 Part L are in around 50 kwhr/m2 ie A3

Passive houses under the same calculations come in generally in the A2 bracket (25 ish kwhr/m2)

Thats why id claim they are near passive... comparing with prior regulations were very far away.

just do it

BryanF wrote: »

my understanding is when the topic is discussed, we never hear much about the 'ecological footprint', mainly just in terms of € / YR heating.

Agree. This is little talked about in the Irish context. The Irish solution is a masonry build with a wider cavity! I noted Denby Dale was the first certified passive house with such a wall build-up. Our continental neighbours are more eco there is no doubt!

BryanF wrote: »

what about a standard that looks for 'ultra-low energy building' in design, build and use?

my opinion on current regs,

1. since 2011 we have a reasonable part L building regulation standards though they still aren't prefect
2. nor is the associated DEAP software
3. and the proposed supervision of the building process definitely NOT
4. is there a policy of low Co2 / embodied energy in construction: no

passive house

1. is there lower co2 use in passive house during occupation: yes, its still higher standard than regs, and its more interested with limiting heat loss
2. is there good associated software: yes, certainly not as many flaws as DEAP, and is more indepth
3. is there a rigorous certification process: yes
4. is there a policy of low Co2 / embodied energy in construction: no

Hard to argue with your opinion.

BryanF wrote: »

so what your saying is you dont spend the money on designer or building process?

No. What I'm saying is don't spend it on both the extra expense of achieving certified passive and the overspec'd heating system that a certified passive house is supposed to save you.

BryanF wrote: »

so what your saying is you dont spend the money on designer or dont trust the phpp software?

Neither. I've spent plenty on both and will still require a more than normal level of supervision to deliver the cost benefit option outlined in my post above. But the question for me is do I spend the extra bucks to get from this to certified passive? I haven't costed it yet but a back of envelope calculation is coming in at between €10k-€20k. Now purely from a financial point of view, why spend this if I'm not going to avail of the supposed saving of not needing to install a conventional heating system?

BryanF wrote: »

you want a medal? i suppose that's a certificate to say its 'certified passive house'. the prize money is about how much it costs to run, id like to build a house and retire in it- at the rate I'm going that's a lot more than 10 year away

The point here is the prize money is the saving on the conventional heating system. The 10yr payback is only on the €1,500 for certification by the way. What if the extra cost is €15k, what is the payback then?

sydthebeat

just do it wrote: »

Will have to look at the link. It's striking the balance between capital outlay and reduced ongoing running costs. One hidden advantage with a simplistic system based on electricity is less maintenance and need for repairs and unit replacement in 10-20 years time. I've a West coast location that favours an air to water heat pump but I'd have a serious concern with this as the sea air is severe on outdoor metal and mechanical items!

i wouldnt envisage electric element in a HRV system as being anyway more durable over time to a wet based system.... actually id claim if you get 10 years maintenance-lite youd be doing very well.

I agree in principle with what you are claiming in the OP, from talking in depth with sas here.
If the principles which are designed are met rigorisly on site,m then a slightkly above certification standard is probably mor ecost effective over time. There are many 'belt and braces' costs, hidden or otherwsie require to be come certified.
I suppose theres a certain irony in the cost involved in proving its a low running cost home.

just do it

fclauson wrote: »

just-do-it visited my house and we spoke about a lot of this

My feedback would be
going certified provided me with building control which is lacking here in Ireland - as one above says with the new regs will change - not sure - but I had a team of over 20 different trades and services all of who knew they would be shot by the main contractor if they messed up

On the UFH thing - I visited a passive house which had not UFH and they where retro fitting heated wall panels to provide the heat boost. I recently posted the following on the linked in forum - all figures are quoted in w/m2/day so size of property is removed from the equation.

Not certain why April needed 177% of PHPP heat demand - but I guess that's the variation of the weather for you.

You should note (I am just building the monitoring for this) that the build stayed within a band of 21 to 23 degrees through out this time (as measured at the MVHR) but the variation room to room was probably in the range of 19.5 -> 24 (south rooms being a bit warner than north - kitchen being cooler as the door has been left open in the "fabulous" summer weather this week)

to put this into PHPP speak
Jan PHPP gave 97w/m2/day and I used 35.10 (i.e. 36% of PHPP numbers) - average outside temps 5
Feb 28.41 vs 73.(i.e. 38%) - average temps 5
March 28.41 vs 38.82 (i.e. 73%) and March was coldest on record - average temp 4
April 11.41 vs 6 (i.e. 177%) - average temps 11

the monitoring system is currently giving
Incoming 6.69
Supply 21.75
Extract 21.56
Outgoing 9.69

Thanks for joining in FC. It was a pleasure to visit and you'll appreciate I'm playing devil's advocate here. Thus far there has been a good range of replies.

For me one of the most interesting learning points of the visit was the potential for condensation on internal surface of glazing/ frames should one opt for the cost benefit option I've outlined. This is a compelling reason to choose the window upgrade. Now with choosing this option it is a no-brainer to aim for certified passive. I read your figures with interest. I suppose the monthly figures just show how unusual our weather has been of late. With my other cap on (part-time farmer) I'm only too well aware of this!

I'm interested to hear of the passive house that has subsequently had to retro-fit heated wall panels. God that is disappointing for them. What heating system had they installed originally? The air heater add-on to the MHRV? (apologies I don't know the right name for this!).

P.S. Keep the figures coming, they make for interesting reading;)

just do it

MicktheMan wrote: »

I don't think so.
My understanding from my training is that the heat demand of 15 kWh/m2/yr is an economical one (sweet spot) and not related to the ability of the hrv to heat the house. The ability of solely using the air (through the hrv system) depends on the heating load of the house as distinct from the heat demand. This is because air can only be heated to a certain temperature before the airbourne dust burns and you get an odour.

Btw, if the heating load is too high to allow air heating solely, you still do not necessarily need a wet distribution system!

Thanks Mick, in hindsight this was discussed on here before. I must look into my heat load figures and see what they're like.

sydthebeat

i remember reading in construct ireland about two passive houses in carlow that were heated through elements in the HRV system, ill see if i can find the links.

just do it

sinnerboy wrote: »

By what means do you verify this demand ? I mean assuming not going certified means you aim to "save" money by cutting out the expert oversight - how will you know you are achieving 18kW/m2/yr? . If you mean you have calculated by using DEAP or DEAP + PHPP and are then "going solo" with it then , again , I strongly advise you install a heat distribution system beacuse chances are you will not make the target.

The saving is based on the extra expense of upgrade windows, airtightness, thermal bridging and certification. I assure you if I decide to aim for the 18kWh/m2/yr target it will still be well supervised and well detailed. I've too much invested in this already (both financially and emotionally) to then turn around and take a "ah sure that will do" attitude to the build. But lets just say it ends up performing at 22-25kW/m2/yr, is that such a bad thing? It will still be a hundred times more comfortable than my current abode which was built only 10 years ago and realistically not that much more expensive to run than a certified passive house.

just do it

MicktheMan wrote: »

I'm confused. Are we discussing the merits of going for certification versus not or the economic benefit of achieving the passive house standard? Imo, these are two separate discussions.

It's an economic argument.

MicktheMan wrote: »

In this case, is the theoretical project being supervised by a trained ph consultant or not? I ask this because without the continuous involvement of the ph consultant, how do you know that the house will actually perform at or close to the designed target?

The project is been project managed by the architect who has completed the passive house certifier/ designer course. I've complete confidence in him and at this stage can't talk highly enough of him. But I will say one thing which is off topic, as a complete newbie to this area in 2008, I didn't appreciate the array of professionals in this area and that an architect doesn't necessarily know the most economic way to build or the comparable cost of various items. It's a team thing and this is an important point. I need to know I can get on with and trust every individual involved and that they are open to and willing to work with all the other individuals involved. (I could go on but I've dragged this off-topic enough at this stage).

just do it

sydthebeat wrote: »

i wouldnt envisage electric element in a HRV system as being anyway more durable over time to a wet based system.... actually id claim if you get 10 years maintenance-lite youd be doing very well.

The HRV will go in anyway. Outside of heating the improved air quality it brings and the improved internal living environment are worth it.

sydthebeat wrote: »

I suppose theres a certain irony in the cost involved in proving its a low running cost home.

The Department of Environment could help by allowing for a reduced renewable energy requirement for certified PHs. It's hard to see a scenario ever developing in this country where building control will get to a similar level of sophistication as that required by PH certification. A win-win really, those who go the extra mile are rewarded, and the Department reduces it's building control requirement, not to mention the over-riding goal of reduced carbon emissions.

just do it

1hr 45mins later - time to turn off the PC and have a G&T:D. OH at a cookery demonstration by Nevin Maguire tonight so I'm looking forward to some good dinners over the bank holiday weekend;)

fclauson

sydthebeat wrote: »

i remember reading in construct ireland about two passive houses in carlow that were heated through elements in the HRV system, ill see if i can find the links.

I visited these houses - they live on a knife edge - if you do as I did today open the doors most of day for the fine weather and dogs to go in and out then a system purely heated via the air will not suffice

I have just walked across the kitchen floor bare footed by the now closed sliders and the floor is notably colder where they have been open all day - the HP/UFH will fix that over the next couple of hours as it stabilises the screed back to a consistent temp (remember I am a single zone house) - an MVHR only system would take days to achieve what a little water will do by the time I get up in the morning

BryanF

MOTM wrote: »

If you're referring to the renewables requirement checked by DEAP you should probably say "meet the TGD L requirement".

point taken, but the over sizing of systems by DEAP for compliance is the point I was attempting to make

sinnerboy

just do it wrote: »

Looking at new builds in my county there is no evidence of increased building control as of yet.

Look at the link I posted. Here it is again. I am not talking about new regulations per se i.e. not a new TGD but rather the new PROCEDURES that will take affect from next March.

sinnerboy

just do it wrote: »

Have you been in many houses using this system solely? I haven't and would be interested to visit them.

This one .

sinnerboy

just do it wrote: »

The Irish solution is a masonry build with a wider cavity! I noted Denby Dale was the first certified passive house with such a wall build-up.

My own opinion is that the easiest way to achieve success with an industry as Conservative as house building is to try to stay as close as possible to the local building traditions developed over decades and longer. The cavity wall is embedded here . So we widen it.

Denby Dale really HAD to be a cavity wall because the Yorkshire planners insisted it must be stone faced ergo cavity wall.

And it does have a tiny conventional heating system , comprising of 2 ( count them - 2 ) rads.

sinnerboy

Something to never lose sight of is what I myself call "the low fat yoghurt" affect. ( It's low fat so I will have two them ).

Many studies verify that statistically Certified Passive houses do perform as designed. Here are 2 monitored studies. There is a reassuring grouping of avereged heating demand around the PH target of 15 kwhr/m2/a but take note - a) there are some hardy type who consume a lot less and b) gentler types who consume a lot more.

User behavior is a massive factor in energy performance.

Indeed in Ireland we have not needed PH to produce hunderds of zero energy houses ....

Certified

In relation to the built in carbon argument against using concrete, has there actually been a proper detailed analysis of the different build methods for Ireland?
I would be interested to know if building using timber frame construction with timber imported from different countries (sometimes from the other side of the world) is actually better from an environmental perspective to using the local concrete industry to build?

In relation to ufh in passive house buildings, I think it is a matter of personnel choice a little bit like choosing a natural granite worktop as opposed to Formica. Not all homes are the same and not all occupants live the same.

The mvhr system can be selected if as mentioned previously the heat load is designed to be low enough and you can use a simple post unit water heat exchanger connected to the hot water cylinder. I cannot foresee any maintenance issues apart from possibly replacing a circulating pump?

sinnerboy

Well another environmental factor is cost to the end user. So in other words if a timber framed construction costs a mortgage holder more lets say €40k more ( i.e TF build costs €250k , Conc/CavWall €210K ) than that €40k debt has to be worked for , materials and carbon has to be consumed because of it. I am making a supposition here only I don't have links to quantified studies on the matter.

rockabaloo

When planning a house it's easy to think about now and the near future but if we make it to retirement age and beyond then our demands are likely to be very different.

I've read a passive house would be about 16 degrees Celsius on a cloudy day in winter (without a heating boost via MVHR). When you're older then it may be difficult to be comfortable in your own house.

I'm sure some sort of central heating would be appreciated then.

sinnerboy

rockabaloo wrote: »

Older then it may be difficult to be comfortable in your own house. I'm sure some sort of central heating would be appreciated then.

And younger people , fat people , skinny ones , baldies and hairies too.

I am a big fan of PH but I recognize that my clients will eventually sell their property into a market which will always contain cynics. Even in 30 years time my crystal ball tells me there will be non believers.

So for that reason alone think carefully about eliminating a small boiler (or other heat producing appliance ) and modest UFH or rads. Think of it as an investment which minimizes the risk to your eventual selling price.

A side story , not directly related to PH.
Whilst giving DEAP/BER advice a couple of year backs to a client on a new house that ( is rated A3 ) did not have to have renewables to comply with regs he wanted solar panels anyway. Why ? To fetch more rent. Which he is convinced now works.

So when selling you passive house it will be of benefit for you to point to rads/ufh / boiler etc. for the easily spooked.

fclauson

rockabaloo wrote: »

..

I've read a passive house would be about 16 degrees Celsius on a cloudy day in winter (without a heating boost via MVHR). ...

that just depends on so many factors

1 cloudy day is :rolleyes: - 2 but 5 would be :mad:

Solair

One question I have is whether the standards take account of the very low levels of direct sunlight in Ireland ?

In Scandinavia and Germany you tend to get a lot more heat delivered by the sun simply shining through windows and heating surfaces directly that way even in the depths of winter.

In Ireland, you can go months without significant sunshine.

Obviously this also changes the calculations for the solar panels but I was just wondering if its factored into the overall house too as its a very significant and often forgotten source of natural heat even without any solar panels.

sinnerboy

That question has been asked but not yet answered.

The generation of climate data in Ireland is of paramount importance if we are to address the energy performance of buildings to an acceptable level of predictability.

MOTM

BryanF wrote: »

point taken, but the over sizing of systems by DEAP for compliance is the point I was attempting to make

DEAPs water heating demand tapers off as houses get larger. Makes sense. You won't have 20 people living in a mansion. I.e. if trying to meet the 10kwh per m2 requirement using properly sized solar DHW in a mansion you won't succeed. Would've been easier if DECLG quantified a reasonable proportion as a proportion rather than an absolute value. Sigh.

fclauson

sinnerboy wrote: »

That question has been asked but not yet answered.

I helped John move his Passive house around Ireland - fascinating how the demand changes based on the local weather data

live in valentia for a cheap time as there is loads of solar gain to be had

mfceiling

fclauson wrote: »

I helped John move his Passive house around Ireland - fascinating how the demand changes based on the local weather data

live in valentia for a cheap time as there is loads of solar gain to be had

Beautiful part of the country so it's win win!!

daver123

Personally i think he whole passive house thing is over rated

Eoghan Barra

daver123 wrote: »

Personally i think he whole passive house thing is over rated

Why, pray tell?

fclauson

daver123 wrote: »

Personally i think he whole passive house thing is over rated

and me - tell me why

sydthebeat

fclauson wrote: »

and me - tell me why

Don't feed the troll guys, he pops up here every so often with rubbish like this.