Building methods for passiv standard?

keru

We're about to start building our house and have for ambition to go without central heating. So up to passive standards but not worried about certification.
I have looked extensively at timber frame options but before we decide which building route to take I feel I should also look at the alternative of wide cavity wall method purely on a cost basis. In your experience is one more expensive than the other?
Is airtightness harder to achieve on concrete build?
I am also wary of man made insulation products on health and also environment grounds. Can anyone prove me wrong/reassure me? Thanks!

beyondpassive

keru wrote: »

We're about to start building our house and have for ambition to go without central heating. So up to passive standards but not worried about certification.

Technically you can heat a Passivhaus with a 3 kW heater, (think hairdryer left on 24/7 for the heating season) However in order to comply with building regulation ypu will need to provide a 'reasonable' proportion of renewables, perversely the lower the enegry demand the higher the proportion of renewables you need to supply. You can use PV but this is difficult to justify economically, so most homes use Solar Thermal Panels, which work with wet central heating systems. This can be delivered through the house by rads, underfloor or duct heaters

keru wrote: »

I have looked extensively at timber frame options but before we decide which building route to take I feel I should also look at the alternative of wide cavity wall method purely on a cost basis. In your experience is one more expensive than the other?

A good quality next generation timber frame with softboard, panelvent, 200mm cellulose fill, air tight smart membrane, 60mm insulated services cavity and plasterboard is ever so slightly more expensive than a 250mm silver bead filled wide cavity, but this is easily justified by having quick erection and enclosure and fast drying out. Its not a matter of comparing the cost of materials alone but the time and attention to detail needed for ultralow energy houses.

keru wrote: »

Is airtightness harder to achieve on concrete build?

Much of a muchness depends on the site crew, supervision and the quality of construction details and airtighness strategy. We've tested 0.22 on timber frame and 0.25 ACH's on wide cavity.

keru wrote: »

I am also wary of man made insulation products on health and also environment grounds. Can anyone prove me wrong/reassure me? Thanks!

Most polymer based insulations are pentane or co2 blown which is fairly inert. Styrene itself is a carcinogen but the risk is negligible, most of our food and drink is sealed in polystyrene and this isn't seen as a risk, although we are seeing elevated oestrogen levels in young people attributed to plastic bottles. I'd focus on the thermal and hygroscopic performance of natural materials and the higher thermal capacity, which give them huge advantages.

sydthebeat

beyondpassive wrote: »

..... We've tested 0.22 on timber frame and 0.25 ACH's on wide cavity.
.......

are those n50 / q50 figures...... or actually ac/h ???

beyondpassive

sydthebeat wrote: »

are those n50 / q50 figures...... or actually ac/h ???

They are n50 air leakage or air changes per hour at 50 pascals positive and negative pressure average tested. Both houses tested have volume numbers (ach's) fairly close to the envelope area numbers (in m3/hr permeability). So in this case you can take it that Q50 and n50 are are very close to interchangable. The q50 result divided by 20 is inputted into DEAP as the adjusted leakage at normal pressure.

BryanF

keru wrote: »

We're about to start building our house and have for ambition to go without central heating.

its a myth that a PassivHaus has no heating. As said above and elsewhere on this forum, designers still seem to oversize or install a backup heating system, just in case... the currently BER software also conflicts with the PH methodology and causes an over complication of what is meant to be a simple 'build tight, ventilate right' passive house philosophy

So up to passive standards but not worried about certification.

what do you mean by this? do you mean that whoever is overseeing your build will be contracted to build a 'passivhaus' to the prescribed heating load, Air change rate and KWH/m2/y? but just not pay the PH institute to check its complaince and issue the cert? or do you mean you'll employ a builder who will offer you cheaper options, renegue on the thermal bridge free detailing, not achieve the ACR, 1.5w/m2k windows frames and come in at roughly twice the PH standard? - still an admirable level of efficiency to attain but the term 'near passive' or 'Up to passive' should not be used - that's what the BER rating is for.

I have looked extensively at timber frame options but before we decide which building route to take I feel I should also look at the alternative of wide cavity wall method purely on a cost basis. In your experience is one more expensive than the other?

cavity block is cheaper on paper. there's no getting around it. i have looked into this and considered it in conjunction with the embodied energy/Co2 etc.. timber frame can be easier to control, cleaner, more precise, quicker to ensemble and get watertight but costs more and there's fewer skilled at it in Ireland + it can be hard (or more expensive again) to actually get local structural timber, environ racking board etc

Is airtightness harder to achieve on concrete build?

that depends on workmanship + specification, detailing and not taking the cheapest quote because its doubtful the know-how or time is budgeted for

I am also wary of man made insulation products on health and also environment grounds

my preference would always be for natural solutions. hemplime, rammed earth, straw etc can be a step to far for many who have grown up along side the concrete federation, so the best compromise imo is timber frame as it can be sourced sustainably and compliment natural materials, from cellulose, to hemp, to mineral wool depending on your eco ideals (it can also be designed/incorporate a breathable fabric which in-lieu of MVHR will help dissipate any harmful gases, water vapour etc)

Can anyone prove me wrong/reassure me? Thanks!

you a right to wary of man made materials, and the building fabric is an easy place to start. what you need to decide is where you feel is the acceptable compromise, as you will/ have compromised (as we all have).. expecting a baby, first things first: paint the kids room - creating a VOC /petrochemical nursery..
May i ask, if your chosen site requires you to get into your car for work, school, shop etc? then on the environmental grounds you need to start with a better site location...

keru

Thank you both very much for all that. It seems my original plans are not so out there after all?
By no central heating I mean we don't plan to put in conventional boiler plus plumbing for rads or underfloor heating. We plan on having solar panels and buffer tank with immersion back-up for summer hot water then a stove with back boiler to back it up in winter as well as produce some room heating and supply rads in bathrooms. I have heard of such a set up in a Construct Ireland article and it referred to this system as a "no central heating house". Coupled with "passive house features such as overall house U-values near 0.12, ACH below 0.6 and passive windows, and HRV it seems to be a reasonable and hopefully affordable way to get a very low running cost house even if it isn't a "passiv house".

beyondpassive

keru wrote: »

Thank you both very much for all that. It seems my original plans are not so out there after all?
By no central heating I mean we don't plan to put in conventional boiler plus plumbing for rads or underfloor heating. We plan on having solar panels and buffer tank with immersion back-up for summer hot water then a stove with back boiler to back it up in winter as well as produce some room heating and supply rads in bathrooms. I have heard of such a set up in a Construct Ireland article and it referred to this system as a "no central heating house". Coupled with "passive house features such as overall house U-values near 0.12, ACH below 0.6 and passive windows, and HRV it seems to be a reasonable and hopefully affordable way to get a very low running cost house even if it isn't a "passiv house".

Would you plan on putting some of the heat from the buffer then into a heating coil in the ventiltion.

A lot of people aiming towards passive, devise similar configurations, but as the design and Bill of quantities develop, they invariably stick in a boiler and a few loops of underfloor. Pricewise these represent a relatively small proportion of your heating plant, and it can be better to have them in and not use them than otherwise. There may come a time when loading the stove with seasoned timber and cleaning ashes once or twice isnt as much fun or isnt possible due to other commitments. Its also important in the event you had to sell as SAS has pointed out in another thread.

I would also note that the Passivhaus concept and MHRV are designed around supplying a fairly constant and consistent low grade heat supply to the house. Steep ramps in Heat at 6.30 and 4.30 are very old school, and waiting for

Then again if you work from home, or are a farmer it may work, just to relie on seasoned slow growth timber. You can cancel the Gym membership too, as they say timber heats you three times

BarneyMc

beyondpassive wrote: »

Would you plan on putting some of the heat from the buffer then into a heating coil in the ventiltion.

A lot of people aiming towards passive, devise similar configurations, but as the design and Bill of quantities develop, they invariably stick in a boiler and a few loops of underfloor.

Using the ventilation system to carry the heat around the house seems like a no brainer. What is the expense of getting the heat from the buffer tank into a heating coil in the ventilation? I would have thought it modest.

keru

If the HRV could heat the house out of the buffer tank hot water that would be the most logical. After all what is the point to go to the expense of going passive and then stick in a boiler and under floor "just in case"?
What I need to determine is the most efficient way to provide hot water to the house and yes, I agree, lighting the stove every day might get tiresome. I haven't looked at wood pellet burner. It can be automated can't it? Is the cost much higher? Unfortunatly budget is very very tight:o

sas

keru wrote: »

If the HRV could heat the house out of the buffer tank hot water that would be the most logical. After all what is the point to go to the expense of going passive and then stick in a boiler and under floor "just in case"?
What I need to determine is the most efficient way to provide hot water to the house and yes, I agree, lighting the stove every day might get tiresome. I haven't looked at wood pellet burner. It can be automated can't it? Is the cost much higher? Unfortunatly budget is very very tight:o

I'm going to put this as politely and as gently as I can. If your budget is very very tight, aim to borrow from passive\low energy principles, but forget about passive. You can't afford it. This is meant with your very best interests in mind. I'll pm you my contact details so you can test this with me if you like. In case you've not read much here, I'm finishing a certified PH build so am fully aware of the costs involved of going passive.

I've posted this multiple times before so here's the short version. My brother in law built a house exactly the same size (to the sq ft) as ours. Ours is a box, there's is a typical boom time design. They spent 100k less than us on the structure. They are getting by with approx 1k oil bills per year on that house. His missus likes the house tropical, believe me. MOeny wise they win hands down.

Think of it like this, assuming you are borrowing for the build.

100k for a low enery spec.
110k for a ph spec.

You're borrowing 10k over say 30 years, reasonable to assume you'll pay back 20k.

So in order to break even you need to spend €666 less heating the ph spec vs the low energy spec each year for the 30 years. I don't see it happening.

keru

SAS I agree with you. I never aimed at certified passive but only mean to follow the principles and find the best compromise between build costs and running cost versus servicing the mortgage.
But I would have to put some value on living in a healthier and more ecologically friendly building and I am ready to put a bit more money in the pot to enjoy that. After getting many quotes I am not convinced it is going to cost me that much more to build to the spec I outlined previously if we go direct labour for everything apart from the timber frame structure. Might be delusional but I am working as hard as I can to achieve that.

Do-more

BarneyMc wrote: »

Using the ventilation system to carry the heat around the house seems like a no brainer. What is the expense of getting the heat from the buffer tank into a heating coil in the ventilation? I would have thought it modest.

The problem with this approach is that the heat capacity of air is not great so there is a limit to the amount of heat you can add to the house in this way.

In another thread here somewhere MicktheMan pointed out to me that you can not heat the air above about 60 degrees C as the dust particles in the air will burn and you get a smell in the house.

Also if you have high humidity and high temps in the ducts it will be a breeding ground for all sorts of bugs.

I'm probably going to use duct heating in a limited way to ensure I maintain 16 degrees C in my bedrooms when it is below freezing outside and the calculations are that I will need to only heat the air to 32 deg C to do it. However even at that I am not fully convinced it will work as if I have the HRV on a low fan setting at night to keep the noise down it may not be moving enough air to carry enough heat. If it doesn't work I will put in some small thermostatically controlled electric panel heaters. The largest bedroom only needs 285W to keep it above 16 deg C when it is -10 outside so the energy consumption will be tiny over the full year.

@Keru I'm in a similar boat to yourself except a few months ahead of you, I'm due to break ground next month.

I'd echo what SAS has just said, I'm building a 200m2 dormer bungalow and will build to a low energy spec rather than passive.

I'm sure you could probably calculate it but my gut feeling is that there a point at around 22-25kW/m2/a which is the sweet spot in terms of capital costs vs. running costs. To make gains below around 22kW/m2/a there is a big ramp up in the costs involved.

You can for example pay huge money for the best outside doors and windows.

My house should end up around 22kW/m2/a or perhaps a little higher and all going to plan my running costs for heating and hot water will be under €400 a year.

I could easily spend another €30K-€50K to achieve a fully certified passive house as I would have to increase the spec of the frame, the doors, the windows and the HRV system, but my running costs would only drop by around €250 a year. So as SAS has already said it never pays off.

sas

keru wrote: »

SAS I agree with you. I never aimed at certified passive but only mean to follow the principles and find the best compromise between build costs and running cost versus servicing the mortgage.
But I would have to put some value on living in a healthier and more ecologically friendly building and I am ready to put a bit more money in the pot to enjoy that. After getting many quotes I am not convinced it is going to cost me that much more to build to the spec I outlined previously if we go direct labour for everything apart from the timber frame structure. Might be delusional but I am working as hard as I can to achieve that.

I went direct labour. I continue to be amazed at much certain things cost and how many of them I need e.g. soil pipe, ajs etc. it adds up so quick and this is where I believe most of us selfbuilders fall down and lack the knowledge of a builder. Naturally this is basic stuff to them. Worth keeping in mind.

Also, going direct labour on a house like this puts you responsible for the detailing. If you've time to learn this or already possess the knowledge, then great. Don't down play how much is involved. Don't assume your window company knows how to fit airtightness tape properly or will even be bothered to do it for you.

Good luck with it.

sas

Do-more wrote: »

I'm sure you could probably calculate it but my gut feeling is that there a point at around 22-25kW/m2/a which is the sweet spot in terms of capital costs vs. running costs. To make gains below around 22kW/m2/a there is a big ramp up in the costs involved.

What I've heard in general would agree strongly with your numbers here.

keru

Newby question. Do you get the heat demand values for your house from the PHPP software? If yes how do you get this done? do you have to go through some energy expert and what consultation cost can one expect?
I feel that I am shooting in the dark!

Do-more

keru wrote: »

Newby question. Do you get the heat demand values for your house from the PHPP software? If yes how do you get this done? do you have to go through some energy expert and what consultation cost can one expect?
I feel that I am shooting in the dark!

Yes Keru the basis for all my calculations are taken from PHPP but recently I have also had a heating engineer who is Passive house institute certified run over all the calculations and do individual calcs for all rooms.

You are probably looking at about €1,000 to get a PHPP or if like fclauson on here you like working with spreadsheets you can buy the PHPP software for about €150 but it's a very steep learning curve to use it without proper training.

keru

Thank you. Much to learn yet!:)

Eoghan Barra

Hi Keru,

You don't mention whether your house was designed from the outset with passive in mind. Is most of the glazing towards the south, east and west? Is the design compact in shape, or more complex? Is it split level? Do you have such things as dormer windows and rooflights, which let out a lot of heat? Etc etc.

Anyway, whatever the answers are to those questions, it's still worth striving for as low energy a house as possible.

Like yourself, I am on a tight budget and am aiming for a passive standard build without certification. I also have a lot to learn, but here, for what it's worth, are a few bits of advice:

1. Go direct labour; you'll have a few headaches but a neighbour who's just finished building his (standard) house reckons he saved 50-60k that way.

2. Use wide-cavity construction; the materials are relatively cheap, mostly available locally, and the methods are familiar to the local tradesmen who'll be doing the work. I'm using 200mm of rockwool fullfill, which costs about €7/m2, as opposed to about €100/m2 for external insulation, for example. Granted, there is another leaf of masonry to build, but it's still going to work out way, way less. My inner leaf will be of thermal blocks for better decrement delay and the wall ties will be glass fibre, which have a conductivity 100 times less than steel without any reduction in strength. This set-up should give a u-value of around 0.16 or less.

3. Save elsewhere but get the best windows and doors in terms of energy performance you can afford (i.e. low u-value, high g-value, very well sealed etc). Shop around for them too.

4. Look at insulated foundations; they are a little expensive but you can save a lot if you put them in yourself. Otherwise, pay particular attention to how to reduce the thermal bridge where your inner leaf passes the floor insulation. There are products available such as Marmox thermoblock to help deal with this (I have never used these and have no connection with the company).

5. Read past threads on boards and other forums, you'll learn a lot from other peoples' experiences (I did); check out the Denby Dale Passive House on youtube: they made a series of about 10 videos about building the house, all explained by the architect with diagrams etc in a very clear understandable way. You may not want to imitate everything they did but I found it quite helpful.

Hope that's of some use to you.

sas

Eoghan Barra wrote: »

s.
3. Save elsewhere but get the best windows and doors in terms of energy performance you can afford (i.e. low u-value, high g-value, very well sealed etc). Shop around for them too.

I would highly recommend you shop around too but only with Irish Manufacturers. I've heard nothing but grief (my own experience too) of dealing with Irish agents for foreign windows.

fclauson

sas wrote: »

...... I continue to be amazed at much certain things cost and how many of them I need e.g. soil pipe, ajs etc. it adds up so quick .....

We used a QS - may seem expensive when you pay their bill but its the best money ever spent on a build - and made comparing the building quotes very very easy

sas

fclauson wrote: »

We used a QS - may seem expensive when you pay their bill but its the best money ever spent on a build - and made comparing the building quotes very very easy

Yeah, in my ignorance in the early days of our build a QS was an extravagance of the wealthy!

BarneyMc

Eoghan Barra wrote: »

I'm using 200mm of rockwool fullfill, which costs about €7/m2, as opposed to about €100/m2 for external insulation, for example. Granted, there is another leaf of masonry to build, but it's still going to work out way, way less. My inner leaf will be of thermal blocks for better decrement delay and the wall ties will be glass fibre, which have a conductivity 100 times less than steel without any reduction in strength. This set-up should give a u-value of around 0.16 or less.

Eoghan, would you mind sending me a PM with the manufacturers of the Rockwool, thermal blocks and wall ties you'll be using?

Thermal blocks and glass fibre wall ties are super expensive unless I'm mistaking? Thanks.

Eoghan Barra

Hi Barney,

Rockwool fullfill Cavity Batts from Insulation Distributors Ltd, Dublin

325mm Qwik-fix wall ties from Coghlan engineering, Tullamore; €1.06 each incl. VAT & del.

alphatherm 140mm thick blocks from Acheson & Glover in the north, about €1.30 each + VAT

I have no connection with any of these companies

Do-more

Eoghan Barra wrote: »

4. Look at insulated foundations; they are a little expensive but you can save a lot if you put them in yourself. Otherwise, pay particular attention to how to reduce the thermal bridge where your inner leaf passes the floor insulation. There are products available such as Marmox thermoblock to help deal with this (I have never used these and have no connection with the company).

I don't know if there is a similar system available in Ireland but this is a section of the insulated foundation I am using on my build here in Sweden.



The element I have circled in red can be set at any position to increase or decrease the width of the ring beam and form a thermal break to the main slab. This effectively eliminates any cold bridge in the slab.

Another thing they do here in Sweden and something to consider if you are on a tight budget is to fit double doors on your outside doors, so one opening out and one opening in so you can effectively increase the u values without huge expense. If you put a bit of thought into the design you can have the inner door open and chocked out of the way for much of the year and only have it in use during the heating season when it's most effective.

BarneyMc

Do-more wrote: »

Another thing they do here in Sweden and something to consider if you are on a tight budget is to fit double doors on your outside doors, so one opening out and one opening in so you can effectively increase the u values without huge expense. If you put a bit of thought into the design you can have the inner door open and chocked out of the way for much of the year and only have it in use during the heating season when it's most effective.

So when you open the outside door you're faced straight away with another (internal) door? It's a bit like a 6 inch lobby? Sounds simple but effective!:D

beyondpassive

Eoghan Barra wrote: »

Hi Barney,

Rockwool fullfill Cavity Batts from Insulation Distributors Ltd, Dublin

325mm Qwik-fix wall ties from Coghlan engineering, Tullamore; €1.06 each incl. VAT & del.

alphatherm 140mm thick blocks from Acheson & Glover in the north, about €1.30 each + VAT

I have no connection with any of these companies

We've been using Silver blown bead in cavity

Vartry Eng Stainles steel wall ties

and Quinlite B3 or B5 for footing wall plate.

maybe someone could give the unit prices for these

kboc

beyondpassive wrote: »

We've been using Silver blown bead in cavity

Vartry Eng Stainles steel wall ties

and Quinlite B3 or B5 for footing wall plate.

maybe someone could give the unit prices for these

beyond passive,

how does this spec compare on cost against insulated rafts?

keru

I follow your thinking and it is very reasonable, however, how can you be sure it will only cost you €400 to heat your house in say ten or twenty years time? The way the price of oil, electricity and gas has gone up in recent years doesn't bode well for the future. Unless you can produce your own energy instead of purchasing it surely it makes more sense to lower your need for it?
In conclusion, I believe, but correct me if I am wrong, that your figures do not give enough weight to the rising price of energy. How much weight to give it is the real question and probably need a crystal ball to answer that one!

keru

sas wrote: »

.

So in order to break even you need to spend €666 less heating the ph spec vs the low energy spec each year for the 30 years. I don't see it happening.

This is what i was refering to in my previous post. New to forums, I 'll get the hang of it yet!:P

beyondpassive

kboc wrote: »

beyond passive,

how does this spec compare on cost against insulated rafts?

I don't understand the question?, you can use wide cavity on a thermally broken rising wall or alternativly on an EPS raft (supergrund, viking, isoquick etc.) The raft has zero thermal bridging.(in fact positive psi for Passivhaus), but can be slightly more expensive than strip, but much quicker. I don't see it as fair to compare on mere material costs.

http://www.integrated.ie/wp-content/uploads/2011/08/EPS-rafts.jpg

Do-more

You can never be sure that the house will perform according to the estimates. A lot is down to the ability of your builders in build it properly. Sloppy build quality can make a farce of the best designed house.

Of course no one knows precisely what energy costs are going to be in 20 years time but the point that myself and others on this thread are making is that once you achieve a certain (reasonably low running cost) level of performance the cost of making further savings are no longer economic.

I personally take the approach of getting to a decent level of performance and when new technologies become available at an economic cost I will add them to the house to offset my energy demand.

For example I have almost enough roof space available to offset almost my house's total energy demand using solar PV panels at present efficiencies and thanks to a 35% grant available here in Sweden it's already on the borderline for it to be economic for me do so.

The cost for me to install that much capacity would be about €15,000 so of course it doesn't make economic sense for me to spend €30,000 to reach passive spec for the house which would only reduce my energy demand by less than half.

Hopefully new technology will come along which will increase solar PV efficiency and reduce the cost per kWhr generated. So when it is economic for me to do so I will probably go down that route and end up with a zero or plus energy house.

BarneyMc

beyondpassive wrote: »

http://www.integrated.ie/wp-content/uploads/2011/08/EPS-rafts.jpg

Looks like figures 13 and 14 are 250mm cavity walls built on a raft foundation. What's the main difference between the two? Looks like the top floor screen in fig. 13 is more insulated from the inner leaf than that in fig. 14. Thanks.

kboc

beyondpassive wrote: »

I don't understand the question?, you can use wide cavity on a thermally broken rising wall or alternativly on an EPS raft (supergrund, viking, isoquick etc.) The raft has zero thermal bridging.(in fact positive psi for Passivhaus), but can be slightly more expensive than strip, but much quicker. I don't see it as fair to compare on mere material costs.

http://www.integrated.ie/wp-content/uploads/2011/08/EPS-rafts.jpg

sorry yes i was not clear. I meant a cost between the common strip found incorporating quinlite blocks in comparison to insulated raft.

The fact that it is "only" slightly more expensive, and the other advantages of insulated raft like speed of build, is insulated raft a no brainer really?

(in fact positive psi for Passivhaus)

what is this?


I also seen this on your web site
http://www.integrated.ie/wp-content/uploads/2011/08/Clonard-Passiv-timber-frame-3.jpg

Is the 400mm on the raft and 310mm timber frame insul overkill or is it justified?
impressive looking work

K

beyondpassive

BarneyMc wrote: »

Looks like figures 13 and 14 are 250mm cavity walls built on a raft foundation. What's the main difference between the two? Looks like the top floor screen in fig. 13 is more insulated from the inner leaf than that in fig. 14. Thanks.

EPS formwork rafts are all about ground conditions and loadings, these are two different solutions for two different types of site, this subject gets well into the structural engineers area of expertise so I couldn't comment further.

kboc wrote: »

The fact that it is "only" slightly more expensive, and the other advantages of insulated raft like speed of build, is insulated raft a no brainer really?

You might think so, if only build decisions were rational. There's usually so many emotive reactions, opinions, prejudices and risk aversion decisions made that the obvious solution is the worst one.

kboc wrote: »

"positive psi for Passivhaus" what is this?

The junction is better insulated than the average of the flanking elements (flanking elements being wall+floor or roof and wall or window and wall)

kboc wrote: »

Is the 400mm on the raft and 310mm timber frame insul overkill or is it justified?

For this particular project with its unique shape, using PHPP analysis it showed that this spec could be justified by minimising heat demand to a level where the extra up front investment was recoverable in the short to medium term and the benifits to occupant comfort and heating system effectivness required it.

some recent site photo's on two types of Passive house build method:
http://s1241.photobucket.com/albums/gg516/Beyondpassive/Site%20Photos%20January/

sas

keru wrote: »

I follow your thinking and it is very reasonable, however, how can you be sure it will only cost you €400 to heat your house in say ten or twenty years time? The way the price of oil, electricity and gas has gone up in recent years doesn't bode well for the future. Unless you can produce your own energy instead of purchasing it surely it makes more sense to lower your need for it?
In conclusion, I believe, but correct me if I am wrong, that your figures do not give enough weight to the rising price of energy. How much weight to give it is the real question and probably need a crystal ball to answer that one!

I'm not sure where you are getting the €400 from.

Ok, so you are taking the position that oil will rise in price and that any difference between the heating costs will hence be larger in the future.

If you borrowed the additional money for the better structure, you are also at the mercy of increasing interest rates.

What's to say that there isn't a breakthrough product that will replace oil based systems as our future energy provider. This is looking less likely but it could happen.

My point is that I have spent the additional money to build a passive house. I saved wherever it was possible. I now look at my spend and can see no realistic chance of break even during the lifetime of the mortgage. At which stage the house will require some maintenance (windows replacing for example) which will push any breakeven point out in further into the future.

I've made my point for this thread. Very best of luck with your decisions.

Eoghan Barra

Sas, I'm very surprised and sorry you seem to be regretting having spent the extra on building in extra insulation and a high level of airtightness etc to get to passive standard.

Surely as well as future savings on heating bills this is to some extent also compensated by the few bob you must have saved by not having to build in a central heating system? And surely it's not only a question of economics, but one of comfort, health and general well-being? And is the question of carbon footprint and each individual's impact on the global environment not also relevant here?

I imagine you're very aware of all these aspects or you wouldn't have chosen to go down that road in the first place. To me installing high levels of insulation, mhrv, limiting thermal bridging etc while you're in the process of building is a no-brainer on lots of levels. I think the ones who'll have the biggest regrets are those who are building to what are now standard levels, as houses built in this way will be considered in only a few years time in a similar way to how we now look at old damp, cold, dark stone cabins built a 100 years ago.

Nor are their economic difficulties likely to be much less than yours, but at least you'll have the satisfaction of living in a really decent house.

fclauson

There is a lot of nonsense spoken about Passive build

a) Passive builds do not need normal heating system - nonsense - a passive build needs continuous heat during the cold weather to maintain a constant internal temperature - e.g. mine will need a continuous 3.5Kwh (more if its dark, damp murky and miserable) - every hour of every day its cold - that’s how passive houses work

b) Passive houses are just a little bit more expense than normal - nonsense - MHRV 6K, Airtightness 10K ........ and the list goes on - its expensive to build passsive - DO NOT KID YOURSELF

c) profession help - there are very few people who fully understand how to build passive - there is so much detail to get sorted out that it costs €€€ of professional help to get it right – you will need an

• architect who can give you a good design (its fairly easy to get a box passive but a good design takes skill),
• a passive house consultant to do the maths,
• engineer to do the structural bit (you will not be building using normal techniques),
• an integrated energy consultant to do the heating/Mhrv/solar integration,
• a person who can calculate cold bridges and
• a very very nice bank manager

d) there is "passive approved products " all come at a premium – that’s more €€€€

So I would suggest you need to reflect on your build and follow my mantra

PASSIVE but keep it PRAGMATIC and PRACTICAL whilst being mindful of PRICE

Good luck

sas

Eoghan Barra wrote: »

Sas, I'm very surprised and sorry you seem to be regretting having spent the extra on building in extra insulation and a high level of airtightness etc to get to passive standard.

Surely as well as future savings on heating bills this is to some extent also compensated by the few bob you must have saved by not having to build in a central heating system? And surely it's not only a question of economics, but one of comfort, health and general well-being? And is the question of carbon footprint and each individual's impact on the global environment not also relevant here?

The issue is that the heating system I didn't have to pay for would have cost less than the stove I need to provide hotwater and backup heating in winter. You can't exactly go to waterford for one of this.

I accept the comfort and well being aspect, it should really add to our quality of life.

I don't really care about my carbon footprint. If I did, I wouldn't have built a large concrete house (blocks, concrete floor upstairs, concrete stairs etc) 5 miles from town.

The PH attraction for me was always lower running costs.

I will say that there has never been a better time to build a PH in Ireland. I look through the forums and the magazines and am very jealous of the availability of the systems and knowledge now. I should underline wide cavity was in it's infancy when I started on my journey, this would absolutely be cheaper than the EWI route that I went. With Irish PH certified windows available etc., you could make a real go of it for alot less than we've payed out.

So in summary my recipe for success the 2nd time around:
1. Get PHPP done, forget about certification.
2. Build wide cavity block structure. TF is great, wide cavity is cheaper.
3. Buy windows locally made i.e. PH certification optional
4. Go with rising walls and standard strip foundation system or locally made insulated raft. That german one I imported while great was SOoo expensive.
5. Install HRV system (probably same one I have now).
6. Install oil\lpg backup heating\dhw system
7. Room heating stove only, no PH mandated flue dampers etc
8. Smaller solar array and tank.
9. Install 1 electric shower in the house due to 8.
10. Consider monopitch roof (if planners allowed)
11. Go for a design, not a box shape. It's a home at the end of the day, not a building.
12. Go for a smaller house, divorce not withstanding.
13. Use the same carpenter\foreman. He is the only thing keeping me sane.
14. Take less than 2.5 years to build it

kboc

Very honest and great to see somebody acknowledging areas where improvements can be made SAS.

Some questions;

Build wide cavity block structure. TF is great, this is cheaper

Slightly confused, is the TF cheaper than block?

Smaller solar array and tank

Does the PHPP software not dictate the square meterage here.

Consider monopitch roof (if planners allowed)

Is this a aesthetic reason or something which will help passive design/solar array?

Thanks
K

sas wrote: »

The issue is that the heating system I didn't have to pay for would have cost less than the stove I need to provide hotwater and backup heating in winter. You can't exactly go to waterford for one of this.

I accept the comfort and well being aspect, it should really add to our quality of life.

I don't really care about my carbon footprint. If I did, I wouldn't have built a large concrete house (blocks, concrete floor upstairs, concrete stairs etc) 5 miles from town.

The PH attraction for me was always lower running costs.

I will say that there has never been a better time to build a PH in Ireland. I look through the forums and the magazines and am very jealous of the availability of the systems and knowledge now. I should underline wide cavity was in it's infancy when I started on my journey, this would absolutely be cheaper than the EWI route that I went. With Irish PH certified windows available etc., you could make a real go of it for alot less than we've payed out.

So in summary my recipe for success the 2nd time around:
1. Get PHPP done, forget about certification.
2. Build wide cavity block structure. TF is great, this is cheaper.
3. Buy windows locally made i.e. PH certification optional
4. Go with rising walls and standard strip foundation system or locally made insulated raft. That german one I imported while great was SOoo expensive.
5. Install HRV system (probably same one I have now).
6. Install oil\lpg backup heating\dhw system
7. Room heating stove only, no PH mandated flue dampers etc
8. Smaller solar array and tank.
9. Install 1 electric shower in the house due to 8.
10. Consider monopitch roof (if planners allowed)
11. Go for a design, not a box shape. It's a home at the end of the day, not a building.
12. Go for a smaller house, divorce not withstanding.
13. Use the same carpenter\foreman. He is the only thing keeping me sane.
14. Take less than 2.5 years to build it

sas

kboc wrote: »

Slightly confused, is the TF cheaper than block?

My bad, quailty TF will be more expensive than wide cavity. I've corrected my previous post to reflect this.

kboc wrote: »

Does the PHPP software not dictate the square meterage here.

If you're not going for certification it doesn't dictate anything, it may give an indication.

kboc wrote: »

Is this a aesthetic reason or something which will help passive design/solar array?

I think it would be cheaper to construct, insulate and airtighten. Plus they do look cool!
Granted it would introduce a bloody great big headache regarding the installation of the hrv. Attics do offer certain practicalities.

Do-more

Regarding the solar panels, it will probably be juggling with your Part L requirements which will dictate the minimum amount of solar panels you will use.

DHW is one area of planning which IMO is real finger in the air stuff. Different households can have vastly differing hot water usage and indeed a family's usage can alter as kids grow up or if the family expands.

If I had known last year I would have put an energy monitor on our hot water tank as at present all our water is supplied by an electric immersion but from working back on our electricity bills I estimate that it is between 2500 and 3000kWh per year.

On one level PHPP agrees with this as it estimates DHW usage at a rate of 750kWhr/person/year but because of the size of our house it estimates occupancy at 5.6 people so it bases all it's calculations on a demand of 4200kWhr/a rather than 3000kWhr/a.

In any case once you go over a certain size of solar panels you will be fully meeting your hot water demand in the summer months and adding additional panels gives you a rapidly decreasing return as you will be dumping all your excess summer production.

It will vary with each installation depending on the optimisation of the panels, their performance rating and the anticipated demand but I would guess that around 60 good quality vacuum tubes is the economic sweet spot for a family of four.

Eoghan Barra

sas wrote: »

Buy windows locally made i.e. PH certification optional

Why is it so much better to buy ph (standard, not cert.) windows made in Ireland? Have many people had bad experiences getting them from abroad, for example the UK? What are the potential problems in getting them from abroad - lack of back-up service etc?

Also, is it true that a dedicated wood burning stove (ie not multifuel) will satisfy part L of the regs?

sas

Eoghan Barra wrote: »

Why is it so much better to buy ph (standard, not cert.) windows made in Ireland? Have many people had bad experiences getting them from abroad, for example the UK? What are the potential problems in getting them from abroad - lack of back-up service etc?

Also, is it true that a dedicated wood burning stove (ie not multifuel) will satisfy part L of the regs?

Most (if not all) of the Irish agents for foreign PH windows are small 1-2 man operations. They were probably selling double glazing at one point, then heatpumps for a while and now PH windows.

You are buying from them i.e. your warranty is with them. If they go under the manufacturer is unlikely to deal with you. One of the better known PH windows agencies changed hands in Ireland last year.

In my case the agent had been poorly trained by the manufacturer. I found more things wrong after they'd snagged than they fixed and I know SFA about windows. I made the mistaken of buying from a company knowing I was going to be their 2 or 3rd customer. I assumed the germans would have trained them properly.

I've had my crowd back 3 times already to make adjustments to windows that were sticking and they are due back again this week to address yet more issues.

If I was buying again I'd make sure that whoever I was buying from was easy to bring to court if needs be, so to me that means buy Irish.

If you buy from abroad you need to be aware of the local practises. For example, it appears to be standard practise for German window companies to ship glazing and frames seperately i.e. the glazing is site installed and hence and sealing (siliconing etc) is done on site.

I can't answer the stove question I'm afraid.

sydthebeat

Eoghan Barra wrote: »

Also, is it true that a dedicated wood burning stove (ie not multifuel) will satisfy part L of the regs?

a dedicated wood stove is considered a renewable energy source and contributes towards Part L compliance.
Multi fuel does not.

Whether the stove alone meets the requirement can only be found out by assessment.

JPJ

How do you prevent a thermal bridge where a concrete post is bolted to the concrete raft? Is it necessary?
The steel posts sit in the cavity and support steel beams which are supporting hollowcore, and concrete lintels over windows. So the steel post base plate is sitting in the cavity on a uninsulated concrete raft foundation. Therfore, it may draw in cold from outside the insulated envelope.

So what material can I sit the posts on to stop cold transferring from the raft to the post.

Is it enough just to wrap the post in insulation? I do not think so, but not an expert. What do you think?

beyondpassive

JPJ wrote: »

How do you prevent a thermal bridge where a concrete post is bolted to the concrete raft? Is it necessary?

As steel is such a good conductor and is supporting 'warm side structure, you need to insulate the raft and make it warm too.

JPJ wrote: »

The steel posts sit in the cavity and support steel beams which are supporting hollowcore, and concrete lintels over windows. So the steel post base plate is sitting in the cavity on a uninsulated concrete raft foundation. Therfore, it may draw in cold from outside the insulated envelope.

Too bad, but perhaps you can wrap the post in high performance insulation, if its a 90 PFC in the centre of a 200 cavity you can encase it in 50mm PIR for example.

JPJ wrote: »

So what material can I sit the posts on to stop cold transferring from the raft to the post.

You could ask your engineer to look at a few layers of neoprene isolator with plastic spacers and SS holding down bolts or even a schock connection http://www.schoeck.co.uk but its likely to be prohibitive on the cost side.

JPJ wrote: »

Is it enough just to wrap the post in insulation? I do not think so, but not an expert. What do you think?

completely depend on the application, what heat demand figure are you designing or building to?

Eoghan Barra

Sas and Sydthebeat,

Thanks a lot for your replies.

I was planning on ordering windows from the UK, but I'm having a serious change of heart now.

Sas (or anyone else in the know), would you mind sending me a pm naming the Irish companies you would consider buying passive standard (not cert.) windows off if you were in that position now?

Cheers.

sas

Eoghan Barra wrote: »

Sas (or anyone else in the know), would you mind sending me a pm naming the Irish companies you would consider buying passive standard windows off if you were in that position now?
Cheers.

I'd consider the unthinkable

Apparently the window is very good, doors less so from an airtightness point of view.

I'd consider a good double glazed rather than a triple glazed window to be honest. The premium on passive windows etc is simply too high. My brother in law bought what appears to be a good quality (but bog standard) pvc window for his build. 96m2 for 26k, mine were 42k for 60m2. Comparison isn't directly comparable but that money speaks volumes.

Simple maths:

If you assumed identical structures with the exception of the glazing as above, I spent\borrowed 16k (42k - 26k) more. We'll ignore the fact that there is a 50% difference in the area of what was purchased.

So, over 30 years I'll have spent 32k (16k approximately doubles with interest) more.

So break even savings needs to be approx €1066 per year between the window specs.

I'm not seeing it personally.

JPJ

My BER report states that the house has a primary energy demand of 73 kWh/m2/year with C02 emissions of 18 kg/m2/year. Is this what you are asking for?

Some of the details of the build, the estaimted U values are from the BER report.
House is a two-storey room in roof/dormer style. A cross shape, which unfortunately means most rooms have 3 external walls. Too late before I relaised the implications. Most windows are south facing. Only 1 North facing.
• Concrete raft foundation - un-insulated unfortunately BUT 200 mm underfloor
• 350 mm Cavity block wall: 100mm - 250mm cavity - 100mm. (U = .15)
• Quinn lite Foundation block as first course on the internal wall.
• Wall Ties are Ancon Low Thermal Conductivity
• Under-floor Insulation = 200mm
• Roof 150mm Kingspan Kooltherm K7 between rafters and 72.5mm Kooltherm K17 under the rafters ( U = 0.12). However I am considering going with a foam between rafters for better air-tightness - and using a thicker insulated board under the rafters to compensate to meet the required U value
• Windows & Doors - most likely with U = .8 (Recall the doors have same U but not sure right now)
• Also 12 Velux windows in the roof - most likely triple glazed - but fast running out of cash
• Plan to have Air-tight tape on doors & windows, but relying on the plaster for air-tightness on the blocks hopefully achieving less than 3 ach - but not sure what is possible with block construction. No dry lining of blocks.
• Heat Recovery Ventilation

This house has been planned for some time, I was familiar with the Passive concept, but very few of my advisers were so we are not going for Passive Certification for which I now regret, but still hope to push as far as we can afford and makes sense.

There are 7 steel posts in the house. So is it worthwhile spending maybe €300 or €400 or maybe more getting these Schock thermal plates or similar?

kboc

Eoghan Barra wrote: »

Sas and Sydthebeat,

Thanks a lot for your replies.

I was planning on ordering windows from the UK, but I'm having a serious change of heart now.

Sas (or anyone else in the know), would you mind sending me a pm naming the Irish companies you would consider buying passive standard (not cert.) windows off if you were in that position now?

Cheers.

PM sent

beyondpassive

JPJ wrote: »

My BER report states that the house has a primary energy demand of 73 kWh/m2/year with C02 emissions of 18 kg/m2/year. Is this what you are asking for?

Some of the details of the build, the estaimted U values are from the BER report.
House is a two-storey room in roof/dormer style. A cross shape, which unfortunately means most rooms have 3 external walls. Too late before I relaised the implications. Most windows are south facing. Only 1 North facing.
• Concrete raft foundation - un-insulated unfortunately BUT 200 mm underfloor
• 350 mm Cavity block wall: 100mm - 250mm cavity - 100mm. (U = .15)
• Quinn lite Foundation block as first course on the internal wall.
• Wall Ties are Ancon Low Thermal Conductivity
• Under-floor Insulation = 200mm
• Roof 150mm Kingspan Kooltherm K7 between rafters and 72.5mm Kooltherm K17 under the rafters ( U = 0.12). However I am considering going with a foam between rafters for better air-tightness - and using a thicker insulated board under the rafters to compensate to meet the required U value
• Windows & Doors - most likely with U = .8 (Recall the doors have same U but not sure right now)
• Also 12 Velux windows in the roof - most likely triple glazed - but fast running out of cash
• Plan to have Air-tight tape on doors & windows, but relying on the plaster for air-tightness on the blocks hopefully achieving less than 3 ach - but not sure what is possible with block construction. No dry lining of blocks.
• Heat Recovery Ventilation

This house has been planned for some time, I was familiar with the Passive concept, but very few of my advisers were so we are not going for Passive Certification for which I now regret, but still hope to push as far as we can afford and makes sense.

There are 7 steel posts in the house. So is it worthwhile spending maybe €300 or €400 or maybe more getting these Schock thermal plates or similar?

So its an A3 house, plaster is fully airtight as long as you seal it at all interfaces with other materials. I'd aim for an airtighness of 1 as it sets a high bar for workmanship and will help the efficiency of your MHRV Where you have rooms in the roof, I'd prefer natural materials, although it costs extra, materials like softboard and cellulose, which have better heat retention capacity than lightweight polmer based insulations which have some resistance to heat but no thermal lag propeerties I wouldn't use spray foam unless I had an hygrothermal analysis carried out which shows how it performs when sprayed against the breather membrane.

You'd have to show a detail of where the steel posts are located relative to the cavity and also relative to openings, in order to see what is the best way to keep them warm.